Autoresonant Trap Mass Spectrometry

Transcription

1 8 th Harsh Environment Mass Spectrometry Wokshop Autoresonant Trap Mass Spectrometry (ART MS) Sept 21, 2011 Gerardo A. Brucker and G. Jeffery Rathbone Granville-Phillips Vacuum Instrumentation Brooks Automation, Inc. Longmont, CO 1 ART MS Milestones September 2007: First ART MS disclosure by A. V. Ermakov and B. J. Hinch, Rutgers University (AVS Abstract). October 2007: ART MS technology investigated by Brooks Automation, Inc. November 2007: ART MS technology acquired from Rutgers University. IP submitted. September 2009: First full technical disclosure of ART MS technology with G-P Improvements at 7 th HEMS. April 2010: VQM 830 product SVC Tech Con. 2 1

2 ART MS is a Mass Spectrometer Ionizer Electron Ionization w/ Field Replaceable Filament Assembly Mass Separator 2 Autoresonant Ion Trap: Ion Storage: Electrostatic Ion Ejection: Autoresonance Detector Electron Multiplier 3 ART MS - Mass Separator Mass Separation methodology defines the type of mass spectrometer The ART MS Electrostatic Ion Trap is a new generation mass separation technology Ionization outside the mass separator Mass filter - one m/z at a time Mass-dependent throughput Slow scanning Ionization inside the trap Ion Trap - all ions stored together Mass-dependent ejection Fast spectral output 4 2

3 ART MS Ion Storage 0 Vdc 0 Vdc -1000Vdc Biased trap electrodes define a purely electrostatic anharmonic potential well. All ions generated by electron ionization are stored inside the cylindrical trap. The trap fills with ions. Electrostatic Ion Trap: Ions confined by purely electrostatic fields oscillate at a resonant frequency inversely proportional to m / z Where, m is mass, z is the total charge of the ion Electrostatic confinement = Ultra-low power requirements 5 ART MS Autoresonant Ion Ejection Ionization 130 Vdc -685Vdc 50 mvpp 2MHz to 200KHz in 80msec 125 Vdc Autoresonance: RF Frequency scanned from High (2MHz) to Low (100kHz) RF scan pushes ions when scan frequency matches ion s resonant frequency Mass selective ion ejection Electrostatic confinement = Ultra-low power requirements 6 3

4 The Magic of Autoresonance No useful ion signal is obtained with reversed scans-i.e. autoresonance is key! 7 ART MS - Differentiators Fast - Scan time <100ms Compact - Scalable Low Power DC Bias + Tiny RF Signal (VQM830=7.5W) Single board design No sensor-to- electronics matching Remote electronics (cable interconnect) Wide Pressure Range XHV to 10-5 Torr Unlimited Mass Range (demonstrated to 600 amu) Rugged design w/relaxed mechanical tolerance Single-gas mass axis calibration Ratiometric device 8 4

5 Single Gas Mass-Axis Calibration RF Scan Direction 9 Typical Resolution (VQM 830) Typical Resolving power 150X 10 5

6 User - Adjustable Performance He+Kr+ Xe Gas Mixture - P= 1.1e-7 Torr - M/ M= Kr He + Kr 2+ Xe Xe Low Mass Spectra - High Resolution H amu He amu H amu Excellent Hydrogen detection capabilities No quadrupole Zero Blast! Proton Detection Isotopic Ratios Helium Detection 12 6

7 Mass Range (VQM 830) 13 Mass Range (ART MS Rutgers U) PFTBA spectrum at 1*10-7 torr RF=50mV p-p Rep.Rate=15Hz I e =10 A U e =100V cpm mass/charge Ermakov AV, Hinch BJ., An electrostatic autoresonant ion trap mass spectrometer, Rev. Sci. Instrum. 81 (2010)

8 Speed - ART MS vs. Quadrupole RGA Quad RGA = 1.5 sec, Ion Trap MS= 70 msec amu scan How much information you get in a 70 msec scan Quadrupole N (14) H 2 O (18) N 2 /CO (28) O 2 Ar (32) (40) CO 2 (44) Ion Trap MS How much resolution and gas detection you get in 1.5 seconds Quadrupole missed Freon (fluorocarbon) CF 3 C 2 F 3 H 2 Quadrupole missed Water Mass (amu) Ion Trap MS 15 Speed - Fast Gas Analysis 16 8

9 Excellent UHV Performance 17 Ultra-Low Power mw Consumption Electron Generator Arrays from Burle were used to generate mass spectra. Electrogen P/N On axis ionization was used because it was compatible with P/N selected from Burle Industries/PHOTONIS. EGA Scan - 30 msec - Air & Argon Nitrogen 904 KHz Argon 758 KHz Ion Current (mv) Oxygen 845 KHz Water 1.128MHz Time (msec) 18 9

10 Dynamic Range Single Shot 19 Dynamic Range 10 Shot 20 10

11 Dynamic Range 1000 Shot 8 E-14 Torr 21 Digital Filtering Fast Electrometer Output MIMS Sample Inlet: 40-ppm chloroform in Water Gary McMurtry and Irina Kolotyrkina, SOEST, University of Hawaii and Pacific Environmental Technologies, LLC, Honolulu, HI USA Quadrupole mass spectrum-filtered ART mass spectrum raw ART mass spectrum - filtered 22 11

12 Ratiometric Output - The Ion Bucket 23 PaceTech s - Deep Ocean Mass Spectrometer DAQ/Logic System MIMS Inlet ART MS Sensor Turbo Pump Rough Pump ART MS Control Board- Analog Output Courtesy: Gary McMurtry, SOEST, University of Hawaii and Pacific Environmental Technologies, LLC, Honolulu, HI USA 24 12

13 Questions? 830 VQM Viewer 830 VQM Controller 830 VQM Gauge Total Pressure Kit 25 On-axis Ionization Source (Rutgers U) (1) ESD Ions : Electrons turn around and collide with the back plane of the entry cup generating energetic ESD ions. ESD ions exit the trap without confinement. (2) Ion Leakage: Ions formed close to grid wires at the entry grid can escape the trap through lower potential regions between wires in the exit grid without confinement Transition Transition Energetic ESD Ions escape the trap Entry Grid Exit Grid Entry Cup Ions and electrons need to be kept away from the back plane of the entry cup! 26 13

14 Off-Axis Ionization (Brooks Automation) Electrons are introduced though apertures located offaxis Ions formed away from grid wires Filament e - Off-axis aperture Electron Beam Ionizing region- Confined Ions ESD ions with no line of sight to the exit aperture ESD Region 27 Sensor Configurations Nude Envelope 28 14

15 VQM Controller Highlights 7.5 W power requirement USB Interface SCPI Command set Stand Alone Operation Single Board- Embedded systems Total Pressure Kit Connectivity 80 msec amu scan range Adjustable Parameters Multiple trigger modes External Analog In (VQI, Total Pressure) 29 15