RADIATIONS. ELECTROMAGNETIC WAVES. Talián Csaba Gábor Dept. Biophysics Apr

Transcription

1 RADIATIONS. ELECTROMAGNETIC WAVES. Talián Csaba Gábor Dept. Biophysics Apr

2 WHAT IS RADIATION?

3 PROPAGATION OF ENERGY IN SPACE THROUGH TRAVELLING OF PARTICLES OR WAVES Particle: alfa-, beta-radiantion Electromagnetic radiation Mechanical: sound radiation source radiation irradiated body ENERGY Ionising: - Particle radiation, - UV, - X-ray, - gamma-radiation Non-ionising

4 SOURCE OF RADIATION Ω / isotropic anisotropic Radiant emittance and Irradiance (M and Ein) P 4 Δ Δ Δ Δ

5 Radiant flux: Δ Δ parameter of the radiation itself Flux-density, Intensity Δ Δ Illustrated by current lines

6 r A l constant 2 ~ 1 Non perpendicular cases: E in = E in, max cosα

7 WAVES

8 FERMAT-PRINCIPLE

9 HUYGENS-PRINCIPLE

10 INTERFERENCE, DIFFRACTION

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12 POLARISATION

13 ABSORPTION A OD E ln

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15 THERMAL RADIATION.

16 ELECTROMAGNETIC RADIATION. B 1 B C C. 1

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19 RADIOWAVES EM radiation Properties Production Applications Extremely low frequence (ELF) 3-30 (-300) Hz km Lightning, electric disturbances Military communication (submarines), meteorology Super low frequence (SLF) Hz km Like ELF Like ELF, radio amateurs Ultra low frequence (ULF) Hz km (sound frequence) Outer atmosphere Magnetosphere-research, seizmology, military communication (in ground!) Very low frequence (VLF) 3-30 khz km Lightning Radio navigation, time signals, secure military communication (surface-close submarines) Long frequence (LF) khz 10-1 km Electric noise, lihgtning, arctic light AM broadcasting, timesignals, air navigation, military comm. Medium frequence (MF) 300 khz-3 MHz m AM broadcasting, coastal guard Short frequence (SW) 3-30 MHz m Broadcasting, CB, aviation communication

20 RADIOWAVES EM radiation Properties Production Applications Very high frequence (VHF) MHz 10-1 m FM, URH broadcasting, television, radar, marinal and air navigation, MRI Ultra high frequency (UHF) 300 MHz - 3 GHz 1 m - 10 cm Television, MRI, mobile phone, microwave oven Super high frequency (SHF) 3-30 GHz 10-1 cm WLAN, radar, radioastronomy, satellite television Extremely high frequency (EHF) GHz 1 cm 1 mm Oxygen resonance Radioastronomy, meteorology, telecommunication, radar, wifi, radiation therapy, security scanner

21 EM radiation Microwave (MW) Infrared (IR) Visible light Properties Production Applications GHz 30 cm 0,3 mm Dipole vibrations 300 GHz THz 1 mm nm Covalent bond vibrations ~ nm Excitation energy of weak σ- and π- electrons Semiconductors, vacuum tube (magnetron) Thermal radiation Lasers (CO 2 ) Thermal radiation Luminescence Microwave oven, radar, maser, cable tv and internet, WLAN, GSM, ESR Night vision, termography, military technic (positioning, tracking), heat therapy, temperature measurment, radiating heaters, wireless communication (shortdistance), meteorology, IRspectroscopy, astronomy

22 INFRARED RADIATION

23 EM radiation Ultraviolet( UV) X-ray (XR) Gammaradiation Properties Production Applications 800 THz 30 PHz nm Excitation energy of outer shell electrons 30 PHz - 30 EHz 10 pm - 10 nm Excitation energy of inner shell electrons > 30 EHz < 10 pm Excitation energy of atomic nuclei Thermal radiation, UV arch lamps, UV-laser, UV- LED, gas discharge tubes (Ar) X-ray fluorescence (characteristic) Brehmsstrahlung (continuous) Radioactive decay, electric atmospheric phenomena, nuclear fission and fusion, hypernova, pulsar, quasar, pair production Astronomy, spectroscopy, sterilisation, air and water cleaning, watermark, fire sensation, forensic, light therapy, tanning etc. Imaging, CT, crystallography, x- ray astronomy, security scanner, x-ray microscopy, instumental specroscopy (weldings) Container scan, sterilisation, tumour surgery (gamma-knife), PET, SPECT, gamma-camera

24 LIGHT

25 INTERACTIONS Transmission Scattering Rayleigh Raman Reflexion Absorption Relaxation Internal conversion Intersystem crossing Quenching Luminescence fluorescence phosphorescence

26 ELECTRON TRANSITIONS Splitting energy niveaus Kasha s rule

27 JABLONSKI DIAGRAM

28 SCATTERING Rayleigh elastic Raman non-elastic

29 IONISING RADIATIONS

30 RADIOACTIVE DECAY α β γ

31 X-RAY INTERACTIONS SO: shake-off P: photoionisation A: Auger-decay F: X-ray fluorescence S, RS: scattering

32 Relative penetration Effective range LET = linear energy transfer 2