Ultraviolet resonance Raman spectra of nylon-6 have been investigated with the use of a quasi-continuous UV excitation source based on cw mode-locked Nd:YAG and Nd:YLF lasers. The selective enhancement of the amide vibrational modes is discussed in relation to the reported results for simple amide compounds and polypeptides in aqueous solution. The ultraviolet excitation can extract the amide III mode at 1280 cm<sup>-1</sup> for the first time, from significantly overlapped CH<sub>2</sub> vibrational modes. The UV-enhanced mode is observed at 1380 cm<sup>-1</sup> and is attributed to the controversial amide S mode. We also demonstrate the utility of the present quasi-continuous laser system as an excellent UV source for ultraviolet resonance Raman studies of solid materials.
Gen Katagiri, James D. Leonard, and Terry L. Gustafson, "Ultraviolet Resonance Raman Study of Nylon-6," Appl. Spectrosc. 49, 773-779 (1995)