Spectroscopic ellipsometry (SE) is used to study the dependence of the band-gap energy for Cu2ZnSnSe4 (CZTSe) on temperature ranging from 50 to 350 K. A CZTSe thin film prepared by the pseudo-bulk approach allows direct observation of the fundamental band-gap E0(A,B) in the SE data without need for multi-layer modeling. We obtain accurate energy values for E0(A,B) and its spin-orbit splitting component E0(C) from standard lineshape analysis of the secondenergy-derivative spectra. The E0(A,B) and E0(C) energies for CZTSe decrease with increasing temperature, as for many semiconductors, but their temperature dependencies are relatively weak. Our experimental observation can be explained in terms of relatively small change in bond-length and strong p-d states coupling at the valence band maximum.
Raman and infrared (IR) spectra were recorded for crystalline cytidine samples at 298, 160, 75 and 10 K. Data were taken over the spectral range 20-4000 cm −1 . The wavenumbers of most vibrational modes were found to increase as the temperature was lowered, but several peaks near 3000 cm −1 showed the opposite trend. A number of peaks split into multiplets at low temperature. No evidence was found of any structural phase transitions in this temperature range. Plausible assignments of all main observed features are suggested.
Raman and infrared spectra were recorded for crystalline deoxycytidine samples at 300, 200, 100 and 10 K. Data were taken over the spectral range 20-4000 cm −1 . The wavenumbers of most vibrational modes were found to increase as the temperature was lowered. A number of peaks split into multiplets at low temperature. A new mode, observed at 375 cm −1 , is a marker band for 2 -deoxyribose in cytosinecontaining nucleic acids. Evidence is presented supporting the assignment of marker bands associated with the C3 -endo and C2 -endo puckers of deoxyribose. No clear indication was found of any structural phase transitions in this temperature range. Several hydrogen-stretching modes were found to involve hydrogen bonding. Plausible assignments of all the main features observed are suggested.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.