JEOL 2010 FasTEM & DigitalMicrograph User's Guide

Transcription

1 JEOL 2010 FasTEM & DigitalMicrograph User's Guide Electron Microscopy Laboratory Instititute of Materials Science University of Connecticut The purpose of this manual is to remind you of the essential points covered in your training classes. The information contained herein is incomplete and NOT a substitute for familiarity with the manufacturer's User Manuals. It is NOT intended for use as a 'teach-yourself' guide! CONTENTS:

2 1. GENERAL INFORMATION 2. THE JEOL 2010 CONTROLS 3. LOADING THE SAMPLE HOLDERS 4. GENERATING THE BEAM 5. ALIGNMENT 6. USING DIGITAL MICROGRAPH 7. RECORDING IMAGES 8. HIGH RESOLUTION TEM 9. EELS ACQUISITION 10. EFTEM AQUISITION 11. USING EDAX EDS 12. SHUT-DOWN

3 1. General Information JEOL JEM 2011 FasTEM Filament: LaB 6 Pole Piece Type: Ultra-high resolution (UHR) Resolution: nm Microbeam diameter: 0.5 nm Spherical Aberration: 0.5 mm Chromatic Aberration: 1.1 mm Magnification: 50x 1.5 Mx at 200 kv SAD Camera Lengths: cm at 200 kv Aperture Sizes Condenser: lever left: 120 / 70 / 50 microns lever right: hole / 70 / 20 microns Objective (high contrast): 120 / 60 / 20 / 05 microns SADP: 100 / 50 / 20 / 10 microns Specimen Holders JEOL single-tilt holder. Maximum tilt X: ±20 JEOL double-tilt holder. Max. tilt X: ±20 Y: ±20 Gatan double-tilt, liquid-nitrogen, cold stage. Max. tilt X: ±20 Y: ±20 Probe Control There are 8 spot sizes and 9 α settings in total. Each PROBE CONTROL button gives different combinations: TEM Mode: EDS Mode: NBD Mode: CBD Mode: 3 α's and 5 relatively large spot sizes. 5 α s and 8 small spot sizes (from 40 to 1 nm). A different set of 5 α s and 8 small spot sizes (from 40 to 1 nm). All 9 α's and 8 small spot sizes (from 40 to 1 nm).

4 Cameras The IMS JEOL 2010 FasTEM is equipped with 5 camera/viewing options making it an extremely versatile tool that can accommodate every user s needs: Conventional Phosphorous Viewing Screen and Film Plates The conventional viewing screen is a familiar to all microscopists and has been the traditional means for direct viewing of TEM images. All recent model TEMs come equipped with one or more digital camera and some of the newest TEMs have eliminated the glowing green screen altogether. The IMS JEOL 2010 is also equipped with a conventional film plate camera for recording images that are then developed in the darkroom. DUALVISION Digital Camera The DUALVISION camera is located above the conventional viewing screen and consists of a prism and CCD detector. The electron beam strikes the phosphor-coated prism and the resulting light image is reflected to the CCD. The DUALVISION affords excellent wide-area viewing for low magnification imaging, and can display and record diffraction pattern images. Because the camera is located above the plane of the conventional viewing screen, the image is magnified ~5 times less than the magnification displayed on the TEM information screen. RETRACTABLE MULTISCAN CAMERA (MSC) The RETRACTABLE MSC is located just below the plate camera. Due to its location in the column, this camera displays images at approximately the same magnification as the conventional viewing screen. It is used for viewing and recording images in the medium- to high-magnification range. Gatan Imaging Filter (GIF) MSC and GIF TV-Rate Camera Integrated into the Gatan Imaging Filter are two CCD cameras: the GIF MSC and a TV-rate camera. The GIF MSC is best used for viewing and recording High Resolution images. The TV-rate camera is useful for locating a region of interest on the sample and initial focusing and alignment of high-magnification images, and displays the image on the TV monitor. Because these cameras are physically located at the end of the GIF, some distance away from the plane of the conventional viewing screen, the image is magnified ~20 times greater than the magnification displayed on the TEM information screen. Useful Notes The double-tilt holder inverts the sample, the single-tilt does not. JEOL state that the scale marker on the negative is correct within ± 5%.

5 There is no rotation of image relative to diffraction pattern in the MAG 1 / MAG 2 range of 12kX to 100kX. Above 100kX image rotation is ~30 CCW. At 200 kv, the eucentric voltage for the UHR pole piece is 4.33 volts (DV set to zero). This is clockwise (CW) This is counter-clockwise (CCW) Be sure to log the column pressure and filament hours into the LOGBOOK before you begin, and complete the LOGBOOK, the INSTRUMENT LOG SHEET, and the FILM USE log sheet when finished.

6 2. The JEOL 2010 Controls LEFT PANEL L EM STOP. Emergency use only. Instantly turns off power to all systems. 2. HT COND. No function. 3. PANEL LIGHT. Sets brightness of panel lighting. 4. ROOM LAMP. No function. 5. BIAS. COURSE. FINE. Sets bias of Wehnelt. 6. ACCL VOLTAGE. UP. DOWN. Manual control of accelerating voltage setting. 7. ACCL VOLTAGE. Ready light. When lit, accelerating voltage may be turned on. 8. HT. Accelerating voltage on/off control. 9. BEAM CURRENT. Digital display. 10. FILAMENT. Ready light. When lit, filament may be turned on. 11. ON. Filament on/off control. 12. Filament heating manual control. 13. PROBE CONTROL. Selection of mode of operation. TEM. Normal probe mode. EDS. Small probe of high current for EDXS. NBD. Small probe of low convergence for nano-beam diffraction. CBD. Small probe of high convergence for convergent beam diffraction. 14. ALPHA-SELECTOR. Sets convergence angle of condenser lens. 15. COND STIG. Energizes condenser lens stigmation control. 16. OBJ STIG. Energizes objective lens stigmation control. 17. Objective lens stigmation memory selector. 18. Dark Tilt (dark field) memory selector. 19. DARK TILT. Energizes controls for displacement of beam in dark field mode. 20. BRIGHT TILT. Energizes controls for displacement of beam in bright field mode. 21. IMAGE SHIFT. Energizes controls for displacement of image. 22. SPOT SIZE. Selector of condenser lens spot size.

7 23. BRIGHTNESS. Controls C2 lens strength. 24. CRS. Coarse setting of brightness/shift. 25. CRS. Coarse setting of deflectors. 26. SHIFT. Left shift knob. 27. DEF. Left deflector knob. LOWER LEFT PANEL L POWER. I. O. Main power on/off. Switches off components progressively. 2. Lens power switches. Maintenance only. 3. BAKE OUT. Maintenance only. 4. ACD. Anti-contamination dewar heater. Press to start the LN 2 dewar evacuation. 5. BAKEOUT TIMER. Maintenance only. 6. Column and Gun Vent controls. Maintenance only. 7. Low Vacuum gauge. 8. FILAMENT. Total time filament has been on. 9. POWER. Total time power has been on.

8 RIGHT PANEL R Z UP/DOWN. No function. 2. SHIFT. Right shift knob. 3. DEF. Right deflector knob. 4. FUNCTION. MAG1. Normal magnification mode. Range 6kX to 1.5MX. Returns magnification to last selected magnification when pressed. 5. FUNCTION. MAG2. Normal magnification mode. Range 6kX to 1.5MX. Returns magnification to 40kX when pressed. 6. FUNCTION. LOW MAG. Magnification range 0.1kX to 3kX. 7. OBJ FOCUS. Image focusing control. Inner knob- fine. Outer knob- coarse. 8. STEP. CRS. Increases coarseness of focus knobs. 9. WOBBLER. IMAGE X. Image wobbles in +/- X direction. Aide to focusing. 10. WOBBLER. IMAGE Y. Image wobbles in +/- Y direction. Aide to focusing. 11. WOBBLER. HT. Causes accelerating voltage to fluctuate. Aide to Voltage Centering alignment. 12. SAM/ROCK. Selected area magnification image mode selector. Used to set up SADP. 13. DIFF. Diffraction mode selector. 14. DIFF FOCUS. Focus control for SAM and DIFF modes. 15. SELECTOR. Increase/decrease magnification and camera length. 16. EXP TIME. SHORT. LONG. Film camera manual exposure setting control. 17. TV IMAGE. No function. 18. SCREEN. Raise/lower the viewing screen. 19. SHUTTER. AUTO. Selects auto or manual exposure settings for film camera. 20. PHOTO. Causes image to be recorded on film. 21. PANIC. No function. 22. FLC. Free lens control. Do not use.

9 LOWER RIGHT KEYBOARD PANEL R SHIFT. X. Y. Varies current in 1 st deflector coils of selected deflector. 2. DEF. X. Y. Varies current in 2 nd deflector coils of selected deflector. 3. DEFLECTOR. GUN. With SHIFT aligns GUN shift. With DEF aligns GUN tilt. 4. DEFLECTOR. SPOT. Maintenance only. Aligns all condenser spot sizes. 5. DEFLECTOR. COND. With SHIFT same as SHIFT L1 R1. With DEF same as BRIT TILT L1. 6. DEFLECTOR. IMAGE. With SHIFT moves image. With DEF aligns diffraction pattern to common center at all camera lengths. 7. DEFLECTOR. PROJ. With SHIFT moves diffraction pattern. With SHIFT aligns image to common center at all magnifications. 8. CRS. Coarse setting for SHIFT and DEF. 9. WOBBLER. GUN. Aide to column alignment. 10. WOBBLER. OBJ. Aide to Current Centering alignment. 11. STIGMATION. INT. With SHIFT diffraction (Intermediate Lens) stigmation. 12. COND DEF ADJ. SHIFT. Wobbles diffraction pattern. With toggle 13 set to X, use SHIFT X and DEF X to align. Set to Y, use SHIFT Y and DEF Y. 13. X. Y. Move toggle to wobble diffraction in X or Y axis. Center position is OFF. 14. COND DEF ADJ. TILT. Wobbles convergent beam. With toggle 15 set to X, use SHIFT X and DEF X to align. Set to Y, use SHIFT Y and DEF Y. 15. X. Y. Move toggle to wobble beam in X or Y axis. Center position is OFF. 16. N. Normalize. Resets all alignments to saved alignment file. Maintenance only.

10 FasTEM KNOBSET CONTROLLER RECORD. SAVE. Do not use. DETECTOR. Do not use. QUICK BEAM SELECTOR. Press TEM, EDS, or NBD to select probe mode. SPOT SIZE. IMAGE SHIFT. X. Moves image. Useful at high magnification. ALIGNMENT. Select Alignment mode. WOBB. Image wobbler. Aide to focusing. DEF. Beam Shift or Diffraction Shift. STIG. Objective stigmation. 7. X. Y. Knobs used with selected Alignment mode. 8. BRIGHTNESS. Condense or expand the beam. 9. MAG. LOW MAG. SA MAG. SA DIFF. Magnification/Diffraction mode selector. 10. SELECTOR. Magnification or camera length selector. 11. MAG/DIFF FOCUS. Focusing knob. 12. RESET. Reset the Image Shift. 13. IMAGE SHIFT. Y. Moves image. Useful at high magnification. CRS. Course setting on associated knob.

11 Trackball and Joystick Controllers FasTEM is equipped with a trackball for stage movement (X-Y translation) and a joystick for X-Y tilt and Z-axis control. The figure illustrates the functions of the 3-axis joystick controller. X-axis tilt (goniometer) Y-axis tilt (double-tilt only) Z-axis (eucentric height)

12 3. Loading The Sample Holders Single-tilt Holder PUT ON GLOVES! Remove the single-tilt holder from the vacuum storage tubes (Read instructions on wall if unsure how to operate). CAREFULLY carry rod back to the 2010 room. Place holder in plastic support cradle (make sure it s the correct cradle!). Move specimen exchange mount (round plastic support) to the bench top. Use cartridge removing tool to remove the specimen cartridge (see Figure 3.1). Mount specimen cartridge on the specimen exchange mount. Load your sample into the specimen cartridge (see Figure 3.2). Re-locate specimen cartridge in the end of the specimen holder. Figure 3.1: How to remove the specimen cartridge from the single-tilt holder. Figure 3.2: How to load a sample into the single-tilt specimen cartridge.

13 Double-tilt Holder PUT ON GLOVES! Remove the double-tilt holder from the vacuum storage tubes (Read instructions on wall if unsure how to operate). CAREFULLY carry rod back to the 2010 room. Place holder in plastic support cradle (make sure it s the correct cradle!), as shown in Figure 3.3. Make sure that the guide pin faces downward and that the specimen retainer rests on the specimen exchange mount. Tighten the red knob on the clamp mechanism to secure the holder to the cradle. DO NOT ALLOW THE HOLDER TO ROTATE WHILE RETAINER RESTS ON THE SPECIMEN EXCHANGE MOUNT! THIS WILL DAMAGE THE RETAINER JEWEL PIVOT! Figure 3.3: How to place the double-tilt specimen holder on the exchange mount.

14 Loosen the screws on the Be specimen retainer by 2 or 3 turns (see Figure 3.4). Gently lift the two copper springs up and to the side to allow removal of the plate. Place a specimen grid, with the specimen facing downwards, on the retainer. Place the spacer on the grid. (The spacer is NOT needed except when specimen grid is very thin: less than 100 µm, or when specimen is mounted on FIB grid.) Place the plate on the spacer. Place the springs on the retainer such that the locating pins fit through the slot in spring. Tighten the screws GENTLY to secure the plate and specimen. Figure 3.4: How to load a sample into the double-tilt specimen retainer.

15 Inserting Sample Holder into the Microscope Fill the Anti-Contamination Dewar (ACD) with LN 2 : Pour a small amount of LN 2 into dewar and wait ~5 minutes for the liquid to boil over. After boil-over, fill dewar to top. Check that the sample rod o-rings are free from dust and lint. Click SAMPLE CHANGE button on FasTEM Server window. Confirm that FASTEM TILT Y INSTALLED on the SAMPLE EXCHANGE window is selected (A in Figure 3.5). Do NOT select STANDARD TILT Y INSTALLED at ANY time, for double- OR single-tilt holder. Check that SPECIMEN POSITION X, Y, Z and SPECIMEN TILT X, Y are centered at 0. If not, click EXCHANGE on the SAMPLE EXCHANGE window. Click CLOSE when done. (Note: Stage cannot be moved with trackball if SAMPLE EXCHANGE window is open.) A Fig. 3.5: FasTEM Sample Exchange Window Check that both yellow and green LED's on the airlock are not illuminated. Line up guide pin on holder with guide groove on column. CAREFULLY insert holder until it stops (DO NOT TURN at this point!) Figure 3.6: Overview of sample rod insertion and removal.

16 Switch airlock switch to PUMP position (you must pull the switch out as you lift it up.) Yellow LED will light up and goniometer evacuation will begin. Let sample holder pre-pump in this position until green LED lights up (about 5-10 minutes.) After light turns green, turn holder clockwise until it stops moving; the rod will then go further into the column. Keep turning clockwise until the rod stops moving, and then allow the rod to fully enter column. (See schematic diagram in Figure 3.6.) Insert double-tilt holder wire into top plug (B in Figure 3.7.) B Removing Sample Holder: Figure 3.7: FasTEM Y-Tilt connector. Turn down filament current waiting ~1 minutes between every full-step. Turn off FILAMENT. Select SAMPLE CHANGE from FasTEM Server window. Click on EXCHANGE. Make sure SPECIMEN POSITION and SPECIMEN TILT on the FasTEM Client window change to all zeros. Should see only green LED lighted below goniometer. Remove double-tilt-holder wire from plug. Pull holder out until it stops. Turn CCW until it stops. Pull holder out just a little more and turn CCW until it stops. Leave holder in this position. Apply gentle pressure pushing the holder IN. This is to prevent the holder from moving out prematurely. Move switch to AIR position. Wait until you hear the specimen airlock vent (hissing sound after ~30 seconds). Check to see that the green LED below goniometer is off. Pull the holder straight out.

17 4. Generating the Beam Logging on to FasTEM Look for windows task bar at bottom of the screen on the FasTEM PC. Click on FasTEM Server tab if present. Use the password: jeol. The FasTEM Server window will open. If not present, double-click on FasTEM Server icon on the desktop. After connection is established, click on the FasTEM Server tab on the task bar at bottom of PC screen. Use the password: jeol. The FasTEM Server window will open. Double-click on FasTEM Client icon on desktop. Log on with your assigned user-name and password. Stand-By Conditions Before turning on the HT, please check the STATUS tab at the bottom of the FasTEM Client window (see Figure 4.1). The following settings should be displayed: MAG = X 120K Mode = TEM Spot Size = 1 α = 3 Accelerating Voltage = kv Specimen Position X, Y, Z = Specimen Tilt X, Y = 0.0 Mode Spot Size α Accelerating voltage (HT) and FILAMENT must be off! (BEAM CURRENT = 000 µa.) OL and IL Apertures should be in its out position (red dot matched with black dot.) Find the vacuum gauge behind lower Right Panel Door on the JEOL The column pressure should be near 1.5 x 1O -5 Pa. (Read blue scale with selector knob pointing to 1 ma/x 1O -5 Pa.) Fig 4.1: FasTEM Client Window

18

19 Turning on the High Tension Make sure column pressure is at least 1.5 x 10-5 Pa or below. Make sure that FasTEM Server and Client windows are open. Make sure OA and IL apertures are out. Make sure Accelerating Voltage is at 181 kv. Press HT button and monitor dark current (i.e. BEAM CURRENT without the beam). The ACCEL VOLTAGE LED will blink until the dark current reaches ~93 µa. Wait until light stops blinking before continuing. Select the HT tab in the FasTEM Client window (Figure 4.2.) (It may be necessary to scroll to the right using arrows at top of FasTEM Client window to see HT menu tab.) Set TARGET SETTING to Set TOTAL TIME to 8.00 minutes. Do not change any other settings. Select GO. Wait until HT reaches 200 kv and 4 faint beeps are heard. Turning on the Filament If FILAMENT LED is on, press FILAMENT button (Left Panel.) Filament LED will not light and Filament cannot be turned on unless Sample Holder is fully inserted into column. Turn FILAMENT knob, waiting 1 minute for each 1/2 division. At around 4 1/2 or 5, the beam current should increase above the dark current value (i.e. will increase above ~102 µa.) Turn the FILAMENT knob as necessary so that the filament image contains some dark structure (i.e. under-saturated). Continue to the Alignment steps with beam under-saturated. Figure 4.2: FasTEM Client HT Window

20 5. Alignment General Comments Perform the complete alignment while the TEM is set to the mode to be used for session. I.e., select TEM, NBD, EDS, etc. and set alpha and spot size to desired values first. If the beam appears astigmatic during your session (i.e., the condensed spot looks elliptical), first check the voltage centering and correct it if necessary. Then correct the condenser astigmatism, followed by objective astigmatism. 1. Condenser Stigmation Step up the FILAMENT control slowly (waiting 1 minute for each half-step increase) until BEAM CURRENT is about 107 µa. Use BRIGHTNESS knob to condense beam to crossover. The under saturated image of the LaB 6 filament should appear as a black with four brightly illuminated lobes. Press the DEFLECTOR COND STIG button (Left Panel) and use the DEF X & Y knobs (Left and Right Panels) to stigmate the condenser lens. Proper stigmation is when the black of the filament image is sharply focused. Check the focus by turning BRIGHTNESS knob away from and back to crossover. 2. Gun Tilt Alignment Press the DEFLECTOR GUN button on the Keyboard Panel and use the DEF X & Y knobs (Keyboard Panel). Use BRIGHTNESS knob to condense beam to crossover. Adjust the filament image using the DEF X & Y knobs on Keyboard Panel (with the DEFLECTOR GUN button pressed) so that the four bright lobes are of equal illumination, and the black has minimum curvature. Saturate the filament by turning FILAMENT knob to stop bar, WAITING 1 minute for each halfstep. BEAM CURRENT should be 112 µa. 3. CL Aperture Alignment Observe the image on next page carefully. The condenser aperture has two rows of apertures of different sizes. The lever is used to move between rows. Aperture sizes are as follows: lever to left: 120 µm, 70 µm, 50 µm. lever to right: hole, 70 µm, 20 µm. Select the desired CL aperture by turning the large black knob (knob 1) so that the white dot aligns with the black dot (circled). Condense the beam to crossover with BRIGHTNESS knob. Center beam with the SHIFT knobs (Left and Right Panels).

21 Turn the BRIGHTNESS knob CW to spread the beam until the edge of the beam reaches the edge of the viewing screen. Center the spread beam using the aperture alignment knobs on the front (small black knob 2) and the side of the aperture selector. Use knob 3 when lever is to left (as in image below); use knob 4 when lever is to right. Check that beam/aperture are well centered by condensing beam to crossover, then spread again to fill the screen. Make adjustments as needed lever 4. Gun Shift ( Spot Size ) Alignment Condense beam to crossover with BRIGHTNESS knob and center with the SHIFT knobs. Select spot size 5 by moving SPOT SIZE toggle switch to the right. (The larger spot size has the lower number, i.e. spot size 1 is largest; spot size 5 is smallest.) Center beam with SHIFT X & Y knobs (Left and Right Panels). Select spot size 1 by moving SPOT SIZE toggle switch to the left. Center beam by pressing DEFLECTOR GUN button (Keyboard Panel) and using SHIFT X & Y knobs (Keyboard Panel). Reiterate until beam remains centered at spot sizes 1 and 5. Return to spot size 1 when done. 5. Eucentric Height Readjust the eucentric height every time after moving stage to a new region of the sample. Center a recognizable feature of the sample, such as the edge of hole, on the viewing screen. Use a magnification > 100 kx. Select the CONTROL menu at the top of the FasTEM Client window, then select FOCUS SETTING. Click the SET button. This will set DV to 0, which corresponds to the eucentric voltage. (DV = Defocus Value. )

22 Obtain a Gaussian focused image (i.e. minimum contrast) by twisting the joystick knob to move stage up or down. You may press WOBBLER IMAGE X or Y (Right Panel) to aid in focusing the image. 6. Condenser Tilt Purity Condense beam to crossover with BRIGHTNESS knob and center with the SHIFT knobs. On the Keyboard Panel, press the TILT button under the COND DEF ADJ label. Move the TILT toggle switch to X and adjust the SHIFT & DEF X knobs, i.e. the left pair of knobs on the Keyboard Panel, until the central spot does not move. Move the TILT toggle switch to Y and adjust the SHIFT & DEF Y knobs, i.e. the right pair of knobs on the Keyboard Panel, until the central spot does not move. If the beam goes off the screen during these adjustments, use the SHIFT X & Y knobs (Left and Right Panels) to return the beam to the center of the screen. Return the TILT toggle switch back to the center position and deactivate the TILT button. 7. Diffraction Pattern Centering Select FUNCTION SAM/ROCK mode. Spread beam on region of interest. Insert the Intermediate (Selected Area) Aperture of desired size by turning knob 1 to align a white dot with black dot (red and black aligned as circled indicates no aperture inserted). Center aperture with knobs 2 and Press the FUNCTION DIFF button on Right Panel. Center the diffraction pattern with the SHIFT X & Y knobs on the Keyboard Panel when the DEFLECTOR PROJ button is pressed. Insert objective aperture (OA). Sharpen edge of aperture image with DIFF FOCUS (Right Panel). Finely focus diffraction pattern with BRIGHTNESS (Left Panel). Remove OA. Correct diffraction stigmation by pressing INT button (INT = Intermediate Lens) under STIGMATOR on the Keyboard Panel. Use the DEF X & Y knobs on Keyboard Panel.

23 8. Condenser Shift Purity While in FUNCTION DIFF mode, press the SHIFT button under the COND DEF ADJ label on the Keyboard Panel. Move the SHIFT toggle switch to X and adjust the SHIFT & DEF X knobs, i.e. the left pair of knobs on the Keyboard Panel, until the central spot of diffraction pattern converges and does not move. Move the SHIFT toggle switch to Y and adjust the SHIFT & DEF Y knobs, i.e. the right pair of knobs on the Keyboard Panel, until the central spot converges and does not move. Return the SHIFT toggle switch back to the center position and deactivate the SHIFT button. Return to image mode by pressing MAG Voltage Centering Center a recognizable feature of the sample on the viewing screen. Use magnification >120 kx. Confirm it is focused and eucentric. Confirm the Objective Aperture is removed (red dot matching black dot). Press WOBBLER HT on (Right Panel.) Press DEFLECTOR BRIT TILT on (Left Panel), then adjust DEF X & Y knobs (Right and Left Panels) until image expands symmetrically, i.e. no sweep. 10. Objective Aperture Insertion While in FUNCTION DIFF mode, insert the desired objective aperture (OA) by turning the large knob on the manual OA control. Center OA so the central undiffracted spot in centered with small alignment knobs on the side and front of aperture selector. If large adjustments were made during Alignment, it is wise to repeat steps 5 through 9. When changing to another mode or magnification setting or any time the TEM image is not ideal, repeat the appropriate steps. Always adjust Eucentric height after moving to a new area of the sample.

24 6. Using DigitalMicrographTM Introduction DigitalMicrographTM is an application used for acquiring, visualizing, analyzing, and processing digital image data within the context of electron microscopy. DigitalMicrograph (DM) provides the capability through the use of plug-in extensions in the application to control and acquire images and data from CCD cameras, EELS systems, imaging filters, and a variety of other sources. DM communicates with JEOL 2010 through the FasTEM Server to obtain microscope data such as operating kv, magnification settings, etc. In addition, DM enables the user to acquire images from the three digital cameras, one TV-rate camera, the Gatan PEELS, and the Gatan Imaging Filter (GIF). DM displays images within image windows. Other types of windows (called palettes) allow the user to manipulate details of those images and other objects. Still other types of windows give information about an image or the results of analysis or processing algorithms. Figure 6.1: DigitalMicrograph Workplace and Filter Control Windows

25 Any or all of the various palettes can be opened and displayed in the main window by selecting them from the WINDOW pull-down menu. To hide palettes, simply click on the close box in the upper right of the palette. DM has its own PC and monitor, located on the workstation to the left of the JEOL Additional power controls for the CCD cameras and GIF are located on the lower shelves of the workstation. It is normally not necessary to change the settings on the camera controllers. For the advanced user, DM offers a number of additional features such as AutoTune, AutoFocus, Scripting, etc. See DigitalMicrograph 3.4 User s Guide for detailed information on image acquisition, processing and presentation. DM 3.4 User s Guide is available for viewing on the Gatan PC desktop. Starting DigitalMicrograph Confirm that the Gatan Power Supply is on. (Green rocker switch at bottom of instrument rack is lighted.) Start the Gatan Filter Control software first by double-clicking on the Gatan Filter Control icon on the Gatan PC desktop. Wait ~1 minute for the software to finish start-up routine. Double-click on the Gatan DigitalMicrograph icon. Wait ~2 minutes for the software to open. If a message window appears indicating that communication with the TEM was not established, check to see that the FasTEM Server is open on the JEOL PC. If this does not solve the problem, see the TEM Specialist. Using DigitalMicrograph Information on using specific features of DigitalMicrograph are available in the following chapters: Chapter 7 Recording Images with Digital Cameras Chapter 8 High Resolution TEM Chapter 9 EELS Acquisition Chapter 10 EFTEM Acquisition

26 7. Recording Images With Digital Cameras Using the DUALVISION Camera The DUALVISION (also called DUAL VIEW) Camera is located some distance above the normal viewing screen, making it ideal for wide-angle (low magnification) views of the sample. Note that the actual magnification of the image is ~5X less than that indicated on the TEM display. Thus, to view an image at ~5kX set the magnification display to 25kX. The DM software correctly calibrates the scale bar in the image to the true magnification. Viewing Images Center the region of interest of specimen on the conventional TEM viewing screen. Evenly spread the illumination to fill the screen. (It is not necessary to lift the viewing screen.) Confirm that DigitalMicrograph is open and running on the Gatan PC. From the DigitalMicrograph menu bar, choose CAMERA from the CAMERA menu. Select DUALVISION. If not already open, select CAMERA TOOLS and then SHOW ALL from the WINDOW menu. A new palette window similar to Figure 7.1 will open. Selecting AUTO EXPOSURE from the CAMERA VIEW palette will allow DM to automatically set the exposure time. De-selecting will open an input box where the user may enter the exposure time manually. From the CAMERA VIEW palette, click the CAMERA INSERTED check box, then click START VIEW. Adjust BRIGHTNESS so that the marker-box is in the green region of the INTENSITY scale (Fig. 7.1, bottom). Using the Knobset Controls and Trackball, translate, focus, magnify, etc. the image as one would normally do on the TEM Instrument Console. Fig. 7.1: Camera Tools Window To record an image, click START ACQUIRE from the CAMERA ACQUIRE palette (Figure 9.1). AUTO EXPOSURE is selectable on this palette. If de-selected, enter the desired exposure time in the EXPOSURE box.

27 Gain Reference The Gain Reference Image is used by DM to remove the background noise from CCD images. Repeat this step after changing beam conditions; i.e. magnification, intensity, spot-size, etc. or whenever the image quality deteriorates. To prepare a gain reference image, spread the beam so the CCD image is evenly illuminated, then put the beam in hole in the sample. If sample has no hole do not prepare a gain reference image! From the CAMERA menu, select PREPARE GAIN REFERENCE and follow the on-screen instructions. In the PREPARE GAIN REFERENCE window, set TARGET INTENSITY = 2500 and FRAMES TO AVERAGE = 5. Viewing Diffraction Patterns With the DUALVISION Camera, a pneumatically controlled electron-scintillator is inserted into the path of the electron beam. This scintillator converts the beam into light and reflects the image to a CCD camera. The camera in turn converts the image into a digital display. Since the camera is not detecting the intense electron beam directly, it is possible to record diffraction patterns with the DUALVISION Camera. Do NOT attempt to view diffraction patterns with any MSC camera! Retract the DUALVISION by deselecting CAMERA INSERTED box. Select SAMAG mode on the Knobset, or SAM/ROCK on the Left Panel. Find the region of interest while viewing the sample on the conventional viewing screen. Select a small spot size, spread the illumination, insert IL aperture. Switch TEM to DIFF mode. From the CAMERA VIEW palette, click the CAMERA INSERTED check box, then click START VIEW. The diffraction image will appear in a new window in DM. Center the diffraction pattern on the camera window using the DEF knob on the Knobset, or use the SHIFT X & Y knobs on the keyboard panel after pressing DEFLECTOR PROJ button. Focus the diffraction pattern using MAG/DIFF FOCUS on the knobset. Change camera length with the SELECTOR knob. Note: The DUALVISION camera housing has a manual focusing ring. If image fails to focus properly check the position of the camera focusing ring. Better results may be obtained by de-selecting AUTO EXPOSURE and entering an EXPOSURE value manually in the CAMERA VIEW palette. Spreading the illumination and using a smaller spot size may also improve the image quality by reducing the intensity of the central spot. To record a diffraction pattern, click START ACQUIRE from the CAMERA ACQUIRE palette (Figure 7.1). Best results are obtained by de-selecting AUTO EXPOSURE and entering an EXPOSURE value of 10 to 20 seconds in the EXPOSURE box. Try different settings until results are satisfactory.

28 Using the Multiscan Cameras (MSC) The JEOL 2010 has two MSC camera options. The RETRACTABLE MSC camera is the best choice for typical image viewing and recording at magnifications between ~30kX and 1.5MX. Note that the actual magnification of the image when using the RETRACTABLE MSC camera is ~1.3X greater than that indicated on the TEM display. The DM software correctly calibrates the scale bar in the image to the true magnification. The GIF MSC is best for High Resolution imaging. Note that when using the GIF MSC the actual magnification of the image is ~20X greater than that indicated on the TEM display. Thus, to view an image at ~500kX set the magnification display to 25kX. The DM software correctly calibrates the scale bar in the image to the true magnification. Do not attempt to view Diffraction Pattern images with any MSC camera! From the DIGITALMICROGRAPH menu bar, choose CAMERA from the CAMERA menu. Select GIF MSC or RETRACTABLE MSC from the list. After centering the region of interest on the TEM viewing screen and condensing the beam to ~3 cm spot, lift the screen by pressing the SCREEN button on the Right Vertical Panel on the TEM console, or selecting VIEWING SCREEN UP from the FasTEM Client window. If not already open, select CAMERA TOOLS and then SHOW ALL from the WINDOW menu. A new palette window will open similar to Figure 7.1. If using the RETRACTABLE MSC Camera, the CAMERA VIEW palette will display the CAMERA INSERTED check box. Click to insert or retract camera. Selecting AUTO EXPOSURE from the CAMERA VIEW palette will allow DM to automatically set the exposure time. De-selecting will open an input box where the user may enter the exposure time manually. From the CAMERA VIEW palette, click START VIEW. A window will open with a live view of the TEM image that will refresh at a rate dependant on the exposure time. Click STOP VIEW at any time to stop image acquisition. Adjust BRIGHTNESS so that the marker-box is in the green region of the INTENSITY scale (Fig. 7.1, bottom). Using the Knobset Controls and Trackball, translate, focus, magnify, etc. the image as one would normally do at the TEM Instrument Console. Periodically return to the conventional viewing screen to re-center the spot, adjust OA, etc.

29 Gain Reference The Gain Reference Image is used by DM to remove the background noise from CCD images. Repeat this step after changing beam conditions; i.e. magnification, intensity, spot-size, etc. or whenever the image quality deteriorates. To prepare a gain reference image, spread the beam so the CCD image is evenly illuminated, then put the beam in hole in the sample. If sample has no hole DO NOT prepare a gain reference image! From the CAMERA menu, select PREPARE GAIN REFERENCE and follow the on-screen instructions. In the PREPARE GAIN REFERENCE window, set TARGET INTENSITY = 8000 and FRAMES TO AVERAGE = 5. Objective Stigmation Objective lens stigmation may be corrected by using the Fast Fourier Transform (FFT) routine. Adjust MAG to >100 kx. If possible, find an area of amorphous carbon to perform stigmation correction. Select LIVE from the PROCESS menu and then FFT or REDUCED FFT. A new window will open with a live view of the image FFT. With the STIG button lighted on the Knobset, adjust the ALIGNMENT X-Y knobs until a symmetrical donut shaped FFT image is formed (see example in Figure 7.2.) Note: The FFT appearance may be somewhat different for each sample. The goal for proper stigmation is to make it appear circular. It may be useful to defocus the image slightly to improve the contrast in the FFT image. Recording TEM Images with MSC Cameras Figure 7.2: Example of properly stigmated FFT of amorphous carbon. To record an image, click START ACQUIRE from the CAMERA ACQUIRE palette (Figure 7.1). AUTO EXPOSURE is selectable on this palette. If de-selected, enter the desired exposure time in the EXPOSURE box. Save the recorded image by pressing CONTROL + S on the Gatan keyboard, or selecting SAVE AS from the FILE menu. Save images in the USER folder located on the Gatan PC desktop. You may create a new folder with your name or other ID in the USER folder. By default, DM saves images in.dm3 format. This format saves additional information about the microscope conditions, such as magnification, operating kv, etc. To view images in other applications, first convert files to.tif format by choosing SAVE AS from FILE menu, or by using BATCH CONVERT. It may be useful to save images in both formats.

30 8. High Resolution TEM High resolution TEM technique requires much more than just knowing which buttons to press on the microscope. It is imperative that the user understand the theory of phase contrast image formation, image interpretation using FFT, and image simulations. As the TEM will be operating at or near its maximum performance level, it is essential that column alignments be carried out with utmost care. Use double-tilt holder. Allow plenty of time for the TEM to stabilize and specimen drift to completely stop. Select CL aperture size 50 µm or 20 µm. Set spot size = 1, and α = 1 or 2. Use the largest Objective Aperture. Perform the entire microscope alignment after making above selections and while the TEM is set to high magnification (see Chapter 5). Pay particular attention to Condenser Tilt and Shift and Voltage Centering. Choose RETRACTABLE MSC or GIF MSC from the CAMERA menu in Digital Micrograph. The GIF MSC magnifies the image about 20X more than the value indicated on the TEM display. It is probably not necessary to use a magnification higher than 100kX on the display (= about 2MX). Find a very thin, smooth and clean region of the sample for HR TEM. There should be only one layer of sample, i.e. no carbon film, etc. under the sample. In DIFF mode, tilt the sample to a low index (if possible) zone axis. The sample must be oriented on a zone axis to obtain lattice images. Acquire and save the SADP. Note that at a displayed magnifications of 120kX and above, there is a CCW rotation of the image relative to the diffraction pattern. Record the diffraction pattern at the same condenser lens (i.e. Brightness) setting used for the image. The Brightness value is displayed on FasTEM window at the bottom. Select Illumination tab and note value of C2. Do NOT tilt sample holder X-axis more than ± 20 or Y-axis more than ± 20! Carefully perform objective stigmation correction. It is best to find an amorphous region of the sample for this step. (For thin foils of bulk materials, there often is a small region of amorphous carbon at the edge of the hole.) Use REDUCED FFT under LIVE in the PROCESS menu. (See Figure 8.1 for an example of FFT appearance when properly stigmated.) Repeat frequently.

31 Figure 8.1: Example of properly stigmated FFT of carbon film. Even after perfect alignment, exact focusing, and corrected stigmation, capturing a good image is often a matter of luck. At the maximum performance of the TEM, small vibrations, drift or mechanical movements will blur the image. Patience is key. The image below required ~1 hour of patient image acquisition until an unblurred image was captured. Figure 11.2: Raw image of Si <111>. Figure 11.3: IFFT of portion of Fig Obtained on IMS JEOL Lattice spacing between arrows = nm.

32 9. EELS Acquisition Using GIF Auto Filter 1. Align ZLP in TEM Mode Turn on TV monitor. Select the GIF MSC from the CAMERA menu. Be sure that the RETRACTABLE MSC camera is retracted. Have the beam in a hole in the sample (if possible) and condense illumination to ~2 cm on center of the TEM screen. Lift screen. Select the TEM button in the TECHNIQUE group in the AUTO FILTER window. (Figure 9.1.) Insert TV camera by selecting SEARCH button in VIEW group. (You should hear a hiss as the pneumatics insert the camera.) Then click the IDLE button to change it to ACTIVE. (Button will show red dot when IDLE and green dot when ACTIVE.) Click ALIGN ZLP in the COMMANDS group to initiate automated zero-loss alignment routine. (Ensure the METHOD is set to AUTOMATIC in the ZERO- LOSS ALIGNMENT dialog box, by clicking ALIGN ZLP with the ALT key held down.) The routine should automatically find and center the zero-loss peak. Once finished, the TV-rate camera will be automatically reinserted. It is important to ensure that the beam is visible on the TV-rate monitor before proceeding further. If the illumination is very intense, spread the beam; conversely, if the illumination cannot be seen then condense the beam until it can. 2. Tune GIF Click on the TUNE GIF button to initiate the automated alignment routine. This will take several minutes. During the routine, you may be asked to adjust the incident illumination; spread or condense the beam to change intensity. 3. Prepare Gain Reference To prepare a Gain Reference image, put the beam in hole in the sample. Do not prepare Gain Reference if sample does not have a hole! Spread the beam so the CCD image is evenly illuminated. From the CAMERA menu, select PREPARE GAIN REFERENCE and follow the on-screen instructions. In the PREPARE GAIN REFERENCE window, set TARGET INTENSITY = 8000 and FRAMES TO AVERAGE = 5. Fig. 9.1: AutoFilter

33 4. Acquire Zero-Loss Spectrum Click on EELS button in TECHNIQUE group (Figure 9.1.) Follow on-screen instructions, if any. Note: Some COMMANDS shown in Figure 9.1 do not appear when EELS TECHNIQUE is selected. Press the ALT key while clicking on EELS button to open AUTOFILTER TECHNIQUE OPTIONS dialog box (see Figure 9.2.) Enter 200 in BEAM ENERGY box, select 0.10 ev/channel in DISPERSION box, and medium in APERTURE box. Click OK. ALT + click Figure 9.2: AutoFilter Technique Options Window Select ZERO LOSS from the ENERGY group (Figure 9.1.) Click on TURBO button in VIEW group. Click IDLE/ACTIVE button to start acquisition and to view the zero-loss spectrum (Figure 9.3). If the displayed peak is red or yellow, immediately reduce the beam intensity until the spectrum becomes green. Figure 9.3: Example of Zero-Loss Spectrum

34 5. Align ZLP in EELS Mode Shift the zero-loss peak on the spectrum until it aligns with 0. Clicking ALIGN ZLP button in the COMMANDS group will move the peak to the right. Holding SHIFT key while clicking ALIGN ZLP will move the peak to the left. Adjust the FIXED STEP SIZE if necessary in the AUTOFILTER IMAGE RECORDING OPTIONs window obtained by pressing ALT while clicking ALIGN ZLP. 6. Focus Zero-Loss Peak Obtain an image of the zero-loss peak on the TV monitor by selecting TV CAMERA IN from FILTER CONTROL window (Figure 9.4). The zero-loss peak should appear as a bright vertical bar on the TV monitor. If the ZLP is off the screen to the left, click on ALIGN ZLP until it appears at the left edge of the TV monitor. Double-click on ACCOMPA: in ADJUSTMENTS palette in FILTER CONTROL window (Figure 9.4.) Focus the zero-loss peak by making the image on the TV monitor appear straight and narrow. Use the keyboard arrow keys to adjust the shape of the image on the TV monitor. Warning: Moving the mouse will produce the same effect as pressing the arrow keys! It is recommended that the arrow keys be used while keeping hands off the mouse. Press ENTER key to save adjustment; ESC to not save. Repeat for ACCOMPB. Double-click on FOCUS X: in ADJUSTMENTS palette on FILTER CONTROL window (Figure 9.4.) Focus the zero-loss peak by making the image on the TV monitor appear straight and narrow. Use the keyboard arrow keys to adjust the shape of the image on the TV monitor. Warning: Moving the mouse will produce the same effect as pressing the arrow keys! It is recommended that the arrow keys be used while keeping hands off the mouse. Press ENTER key to save adjustment; ESC to not save. Repeat for FOCUS Y: Figure 9.4: Filter Control Window Double-click on SX: in ADJUSTMENTS palette on FILTER CONTROL window (Figure 9.4.) Focus the zero-loss peak by making the image on the TV monitor appear straight and narrow. Use the keyboard arrow keys to adjust the shape of the image on the TV monitor. Press ENTER key to save adjustment; ESC to not save. Repeat for SY:

35 7. Acquire EELS Spectrum When performing EELS analysis, it is best to obtain the EELS spectrum with the TEM in diffraction (DIFF) mode. If you are going on to perform EFTEM, then obtain the EELS spectrum in image (MAG) mode. Find an area of interest on the sample by clicking TEM in the TECHNIQUE palette. In the VIEW palette, select SEARCH to view on the TV monitor, or PREVIEW to view in the DM window. Move the trackball until a region of interest is in view. Condense the beam to a convergent spot on the region of interest. (It may be better to lower the TEM viewing screen and carry out this step at the TEM rather than the MSC camera. Be alert for beam damage and/or contamination build-up when using convergent beam. Reduce spot size/condenser aperture or spread the beam to limit beam intensity.) Switch TEM to diffraction mode. Center the convergent diffraction pattern using the controls on the left keyboard panel (PROJ button). Ensure that the 000 disc is at the center of the viewing screen. Raise the viewing screen. Click EELS in TECHNIQUE palette (Figure 9.1); select ZERO LOSS in the ENERGY palette; click TURBO from VIEW and IDLE/ACTIVE. The EELS spectrum window will open and refresh automatically as long as ACTIVE button is green. If the spectrum is red or yellow, immediately reduce the beam intensity until it becomes green. Re-align the zero-loss peak with 0 ev on the spectrum by clicking ALIGN ZLP in the COMMANDS palette. (Click to move peak left; shift-click to move peak right.) Figure 9.5: Example of EELS spectrum with ZLP misaligned.

36 8. Improving EELS Spectrum Because the spectrum above is scaled to the very high count rate of the zero-loss peak, the characteristic elemental edges from the sample are too small to be seen. It is necessary to shift the spectrum to a higher energy to see the details of the elemental edges. Select CUSTOM from the ENERGY palette. This will make the ENERGY LOSS (ev) option bar active. Clicking on the value in the ENERGY LOSS (ev) bar will open a new window, which asks for the desired value. Figure 9.6: Entering new Energy Loss value. Enter a value that is somewhat lower than the ev of the edges you wish to see. In the example below (Figure 9.7), the Boron edge at ~200 ev is of interest, so a value of was entered. To widen the energy range (x-axis) in the Spectrum, select a higher value (e.g.: 0.5 ev/ch) in the DISPERSION box on the FILTER CONTROL window (Figure 9.4). Click on the IDLE/ACTIVE button to obtain the Spectrum. To increase the counts/reduce the noise, try the following: In DIFF mode: carefully adjust the diffraction shift control (left keyboard panel, PROJ button selected) by small amounts until the best results are obtained. In MAG mode: converge and center the beam, use larger CL aperture and/or larger spot size. Figure 9.7: Example of ideal EELS Spectrum of sample containing B, C and N.

37 9. Saving Spectrum To acquire a Spectrum to save, click ACQUIRE in the COMMANDS palette. Enter EXPOSURE TIME and number of FRAMES TO AVERAGE in new window, then click OK. Increase exposure time and/or frames to average to reduce spectrum noise. For more detailed user information, see EELS With Auto Filter Tutorial pdf file on the Gatan PC Desktop. Comments by Roger: Think about what you are trying to accomplish and plan out your session carefully. With many parameters to play with (spot size, beam intensity, diffraction or image mode, filter control aperture size, condenser aperture size, etc.) it is important to understand the effect of each parameter. While high beam intensity is necessary to obtain clear spectra of high energy edges (e.g. the Si-K edge at 1839 ev), the same intensity settings will seriously damage the EELS detector at low energies (e.g. the C-K edge at 284 ev), so make adjustments appropriately. If expected edges do not appear or appear at wrong energy values, think about the reasons why this is so. Is the zero-loss peak properly aligned at 0 ev? Is the beam alignment optimized for the chosen spot size and apertures? Is the beam centered on the detector? Has the sample moved and the region of interest is no longer under the beam? Is the sample too thick at the region of interest? Excellent results are possible on this instrument if done carefully and intelligently. The Gatan EEL says, Have Fun!

38 10. EFTEM Using GIF Auto Filter Preliminary Information Successful EFTEM mapping requires a sample that is sufficiently thin and elemental changes that are sufficiently strong. Elemental interfaces should be aligned parallel to the beam direction to ensure sharp transitions in the elemental maps. Mapping requires the acquisition of several images in sequence. Excessive sample drift or a featureless image may prevent the automatic image matching software from properly aligning the images. The quality of the EFTEM map is dependent on careful alignment of the TEM and having a well focused and properly stigmated image. It is essential to carefully align the Zero-loss peak before obtaining the EELS Spectrum for EFTEM, otherwise the edge positions in the spectrum will not match the default values listed in the setup windows. 9. Align EELS Follow all the steps in Chapter 9: EELS Acquisition before beginning EFTEM. Acquire a good EELS Spectrum of the elemental edges that are of interest. Confirm that the position and shape of the elemental edges in your spectrum match those in the EELS Atlas. 10. Acquire TEM Image Acquire an image of the region of interest using the GIF MSC camera. Perform careful focus and objective stigmation corrections. 11. EFTEM Jump Ratio Image Select EFTEM from the TECHNIQUE palette. Select CUSTOM from the ENERGY palette. (Figure 10.1) In the COMMANDS palette, hold down the ALT key and click on the button. This will open a new window, as in Figure Figure 10.1

39 Figure 10.2: Ratio Mapping Setup window. Select the element to be mapped by entering the atomic number or the atomic symbol in the ELEMENT boxes. Select the edge to be mapped (i.e. K, L, M, or N) by clicking the EDGE box. Pre-selected values for all the other parameters will automatically be entered in each box. Changes may be made to the PRE-EDGE and POST-EDGE values if desired. The number entered in the box indicates by how much (ev) the center of the window (shown by the white line in the schematic spectrum) will be offset from the elemental edge. Enter the desired value for the width of the windows (shown by the dark shaded regions in the schematic spectrum) in the SLIT WIDTH box. Changes may be saved by clicking the SAVE box. Two different Setups may be saved for each element. Toggle between the setups by clicking the number in the SETUP box. Press OK. A new window will open requesting exposure time. Enter a value (e.g. 15 sec.). Click OK to begin acquiring the jump ratio image. Follow on-screen prompts. It is often best to manually align the Pre-edge and Post-edge images. Click MANUAL in the appropriate prompt window. Position the mouse cursor over the new image window that opens. Hold down the CONTROL key while holding down the left mouse button. The window will alternately flash between the two images. While holding the CONTROL key and left mouse button, move the mouse to shift the image position. When no movement is visible, the images are aligned. Press the ENTER key. If image is noisy, use a longer exposure time. If sample is drifting, use a shorter exposure time.

40 12. EFTEM Elemental Mapping Select EFTEM from the TECHNIQUE palette. Select CUSTOM from the ENERGY palette. (Figure 13.1) In the COMMANDS palette, hold down the ALT key and click on the MAP button. This will open a new window, as in Figure Figure 10.3: Elemental Mapping setup window. Select the element to be mapped by entering the atomic number or the atomic symbol in the ELEMENT boxes. Select the edge to be mapped (i.e. K, L, M, or N) by clicking the EDGE box. Pre-selected values for all the other parameters will automatically be entered in each box. Changes may be made to the PRE-EDGE1, PRE-EDGE2 and POST-EDGE values if desired. The number entered in the box indicates by how much (ev) the center of the window (shown by the white line in the schematic spectrum) will be offset from the elemental edge. Enter the desired value for the width of the windows (shown by the dark shaded regions in the schematic spectrum) in the SLIT WIDTH box. Changes may be saved by clicking the SAVE box. Two different Setups may be saved for each element. Toggle between the setups by clicking the number in the SETUP box. Press OK. A new window will open requesting exposure time. Enter a value (e.g. 15 sec.). Click OK to begin acquiring the jump ratio image. Follow on-screen prompts.

41 It is often best to manually align the Pre-edge and Post-edge images. Click MANUAL in the appropriate prompt window. Position the mouse cursor over the new image window that opens. Hold down the CONTROL key, while holding down the left mouse button. The window will alternately flash between the two images. While holding the CONTROL key and left mouse button, move the mouse to shift the image position. When no movement is visible, the images are aligned. Press the ENTER key. If image is noisy, use a longer exposure time. If sample is drifting, use a shorter exposure time. Common Questions (answers by Colin Trevor): Q1) Why is my Map all fuzzy (not sharp)? A1) You need to focus and stigmate the image better; the inelastic electron image is more sensitive than the elastic image to poor alignment. Q2) Why do I see bright / dark bands at interfaces? A2) Your sample is drifting. Q3) I see very sharp contrast that is not from the sample in bright areas, why? A3) You have saturated the detector in one of the images. Q4) My maps are noisy how do I improve them? A4) a) Make sure the sample is thin; try moving areas. b) Increase the number of counts either by increasing the beam intensity, the exposure time or by averaging frames together. Q5) What size objective aperture should I use? A6) Use an aperture that excludes diffracted beams, as double scattering is unlikely to focus cleanly. See the tables in the back of the GIF manual to see how aperture size and spectral resolution are connected at lower magnifications. Comments by Roger: There are a large number of parameters to play with that will change the appearance of your maps (Pre- and Post-edge positions, slit width, exposure time, etc.) Think about what you are doing. Always acquire an EELS spectrum first, and study the spectrum to determine the position of the windows that makes the most sense. Don t accept the pre-selected values in the setup windows (e.g. Fig 10.2 and 10.3) without determining whether they are appropriate for your needs. Poor results are most often due to insufficient electron current. Move to a thinner region on the sample this allows more electrons to pass through the sample to be detected. Increase beam intensity by using larger CL aperture and larger spot size. Use a longer exposure time. Sharper maps can be obtained by decreasing magnification and using a smaller OL aperture.

42 11. Using EDAX EDS System Preparing to Acquire an EDS Spectrum Use the EDAX PC located to the right of the JEOL TEM. Open RTEM CONTROL by doubleclicking on the RTEM32 icon. Double-click on the EDAX Genesis icon on the desktop to open the EDS acquisition program. Find a region of interest on the sample and center on the viewing screen of the TEM. Tilt the sample holder toward the EDS detector 15 degrees (X tilt = -15 ). Re-center the region of interest, if necessary, and focus the image. While not absolutely necessary, selecting EDS mode by pressing the EDS button on the left-hand vertical panel of the TEM will produce a small beam size with high current. Condense the beam and center it on the region of interest in the sample. Confirm that the objective aperture is removed from the beam path (red dot aligned with black dot). Insert the EDS detector by clicking IN on the RTEM CONTROL window. If the X-ray count rate is too high, the detector will automatically move to the OUT position and RTEM CONTROL will indicate high counts per second (HI-CPS). Before re-inserting the detector, confirm that the objective aperture is removed. Change to a smaller spot size and/or move to a thinner region of the sample to reduce the count rate. Before collecting a spectrum, set the acquisition time by entering a value in the Preset box. Confirm that a value of is entered in the kv box, located above the Collect button. When finding a sample location for EDS it is often best to turn the lights off. To darken the EDAX PC screen, select Blank Screen from the View menu at the top of the Genesis window.

43 Acquiring an EDS Spectrum To begin X-ray acquisition, click Collect at top of the right panel of the Genesis window. Count rate should be <8000 cps (indicated at bottom of Genesis window.) Observe also Dead time (DT%). A DT% between 10 and 40 is desirable. If the X-ray count rate is too high during acquisition, the detector will automatically retract to the OUT position and collection will stop. Before re-inserting the detector, confirm that the objective aperture is removed. Change to a smaller spot size and/or move to a thinner region of the sample to reduce the count rate. When the Preset time has expired acquisition will stop. Manually stop acquisition by clicking Collect. Erase spectrum if desired by clicking Clear. Save or print the spectrum by choosing the appropriate command from the top menu bar. Identifying Spectrum Peaks Click on Peak ID to have the program auto-identify the spectrum peaks. To manually ID peaks, click on the double arrowhead: in the Peak ID box. This will expand the box to reveal new commands. Position the mouse over the peak of interest and click the left button. A list of possible ID s will appear in the Possible box. Enter the element of choice in the Element box or click Z- Z+ to step through the periodic table one element at a time. Or click the EPIC button to open a window with the periodic table. At the bottom of the Peak ID box are several options for labeling the spectrum peaks. Deselect the check mark in the Alpha Lines Only box to have all peaks identified. Select Elem, Shell or Trans to add more details to the peak label. Add absorption peak (ABS), escape peak (ESC) or Sum peak markers if desired. Reduce the Peak ID box by clicking on the double arrowhead: X

44 Quantifying Spectrum Quantifying EDS spectra is a complicated affair with many theoretically algorithms to choose from. It is up to the user to understand the theory of EDS quantification and know which method is most appropriate for their material. Selecting the variables to make the results fit preconceived expectations is not a proper way to quantify EDS data! Expand the Quant box by clicking on the double arrowhead: Click Z List to select the elements to quantify. When oxides are present in the sample, select the oxide ratios for each element by clicking the Type button. Adjust the K Factor and Corrections only if necessary and appropriate. After setting the quantification parameters, click Quant to open a new window with the quantification results. Be aware that the results are accurate to ±5% AT BEST! Sample geometry, detector position, microscope conditions, absorption and fluorescence all will affect the results to greater or lesser degree. It is up to the user to understand these concepts and use the results appropriately! THE PRECISION SUGGESTED BY THE QUANT RESULTS (i.e. 2 decimal places) IS NOT AT ALL REALISTIC!