Explain briefly the principle of Fourier transform spectroscopy as practiced in
ID: 485294 • Letter: E
Question
Explain briefly the principle of Fourier transform spectroscopy as practiced in the FTIR. Specifically, how does one use an inter geometric geometry to get spectra (and why does that work)? What determines the spectral resolution of FTIR and why? How does one do wavelength calibration in FTIR? What advantage(s) does FTIR have relative to simply using a grating spectrometer and scanning the detected wavelength? How many significant figures do you think it is reasonable to cite for the measurements of vibrational absorption frequencies you made in your experiments? Explain how we can use vibrational spectra to estimate the bond dissociation energy of HCl(g)?Explanation / Answer
Vibrational spectroscopy
a) Fourier transform spectroscopy works on the principle that molecules absorb radiation in the infrared region, they get excited. When returning to the ground state they release this extra energy which is measured and spectrum is produced. When the wavelength of light matches with bonds, the bonds stretch or bend.
b) The spectral resolution depends upon the number of molecules of the same type getting excited and the intensity of radiation reaching the detector.
c) Wavelength calibration in FTIR is done, by focussing the detector on to a specific wavelength. When the moelcule absorbs IR light, the radiation coming out is divided and the one at which it gives maximum intensity is the best choosen wavelength.
d) FTIR can detect the type of bonds formed by atoms and it is specific for specific type of bonds. These features are unique to IR.
e) For vibrational spectroscopy, two significant figures are needed.
f) The wavelength at which the HCl molecule gets excited is inversely related to the energy of dissociation for HCl.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.