Applications of polarization-division interferometry and vibrational optical activity

Polarization-division interferometry (PDI) has been demonstrated as a new useful technique in vibrational spectroscopy. The following studies have been accomplished with the PDI. (a) Polarization-division beamsplitters have been constructed with KBr, KRS-5 and mylar substrates and their performance has been evaluated. (b) VCD spectra below 650 cm{dollar}sp{lcub}-1{rcub}{dollar} have been measured using mylar beamsplitter for the first time. (c) It is demonstrated that birefringence can be measured with PDI. (d) Dichroism measurements in the presence of interfering water absorption indicated advantages of PDI over conventional technique. (e) Thin film and monolayer measurements at air/water and air/metal interface were demonstrated to be feasible with PDI. (f) Time-resolved vibrational dichroism measurements were shown to be feasible with PDI.; The Raman optical activity (ROA) properties associated with the peptide group in chiral conformers of N-methylacetamide were investigated to serve as the simplest model for peptide and protein molecules. N-Acetyl-{dollar}Nspprime{dollar}-methyl-L-alaninamide (NANMLA) is used as a model compound to deduce the conformational information of peptide and protein molecules. The ROA spectra of nine conformers of NANMLA were calculated. The predominant conformations of N-Acetyl-{dollar}Nspprime{dollar}-methyl- scL-alanimamide in solution are suggested using ROA analysis. Experimental ROA spectra of L-ala-L-ala-L-alanine, {dollar}alpha{dollar}-chymotrypsin and poly-L-lysine reported in the literature were compared with predicted ROA spectra of NANMLA conformers. These results demonstrated that ROA is a feasible technique to reveal the stereochemical information of protein molecules.