CHY203 - Spectroscopy-Comparison of X-Ray & IR spectroscopy Instruments

Spectroscopy-Comparison of X-Ray & IR spectroscopy Instruments Comparison & Contrast X-Ray Spectroscopy IR Spectroscopy Wavelength Range of emr The wavelength ranges about 0.0001 nm to 10 nm, and x-ray spectroscopy is ranging approximately from 0.01nm to 2.5 nm region of the spectrum IR region of the spectrum has a wavelength ranges from the end of the red visible region of approximately 780 nm to 1,000,000 nm Near-IR range (0.78-2.5m) Mid-IR range (2.5-50m) Far-IR ranges (50-1000m) Energy of emr The energy of emr is high E= ho = h c/o= Ve The energy is low associated by a vibrational and rotational transition E= h c/ = h Sources and their spectral outputs 1.X-radiation from Radioactive source a. x-radiation produced by radioactive decay b. many alpha & beta emission c. K-capture(electron capture) produce x-radiation d. Gamma radiation produced by intranuclear reactions same as x-radiation 2. x-radiation from a Synchrotron 3. Primary x-radiation produced by expose of a metal target with high energy of electron 4. secondary x-radiation produces by exposing a material to a beam of primary x-radiation 1. Nernst Glower: made of ZrO2 and Y2O3 with platinum useful in near & mid IR 2.Globar: same output spectral of the Nernst Glower except at <5m the Globar had a greater out put 3.Incandescent Wire : has a lower intensity than Nernst Glower and the Globar 4.Mercury Arc: used in the far IR region 5.Tungsten filament : used as an IR source in the near-IR region of the spectrum (0.78-2.5 m) 6.CO2 laser: used as IR source in the region 900-1100 cm-1 Dispersive Devices 1. monochromatic ( filters and narrow collimators) 2. Crystal structure 1.Dispersive IR Spectrophotometer : which consists of a. double beam b. signal ‘chopping’ c. optical design and configuration d. Null type detector limitations 2. Interferometric (multiplexed) Spectrometers has two types: a. Fourier transform b. Hadamard transform (not widely used) Materials used for optical components 1. window of beryllium (Be) 2. Mirror including grating 3. X-ray tube (e.g. metal tube) 4. Focusing Cap 1. Mirrors including: focusing and gratings that made front surface reflecting 2. Sample holders and cell windows that made from transparent materials to IR radiation a. near IR- fused silica or quartz Slicate glass, NaCl, KBr, LiF, TIBr & TII b. mid IR- NaCl, KBr, LiF, TIBr,TII & ZnSe c. far IR- KBr, TIBr & TII Detectors 1.Gas-filled detector a. Ionization Chamber b. Proportional Counter c. Geiger counter 2.Scintillation counters detector 3. Semiconductor detector a. Ge (Li) detector b. Si (Li) detector 1.Thermal detector a. thermocouple b. blometer c. Golay tube (pneumatic) 2.Pyroelectric detector 3.Photo-conductioing detector