532‐nm‐excited hyper‐Raman spectroscopy of amino acids

This paper reports the hyper‐Raman (HR) spectra of the 20 amino acids in aqueous solution in the range of 400–1,800 cm−1 with an excitation wavelength of 532 nm. A remarkable common feature in the nonresonance HR spectra is the large intensity of the HR bands of the COO− group. Whereas the peak position is mostly identical between the HR and Raman spectra, the intensity pattern is not. We discuss the similarities and dissimilarities between the pattern of the two spectra of each amino acid and give possible assignments to each HR band by comparing them with those of the corresponding Raman band. This study offers a reference for the HR spectra of the amino acids as the basic building block of proteins. It helps interpret the HR spectra of proteins and peptides. This paper reports the hyper‐Raman (HR) spectra of the 19 amino acids (20 except for Phe) with an excitation wavelength of 532 nm. Similarities and dissimilarities with the Raman spectrum are described, and possible assignment is given for each HR band. The data set offers a reference to study the structures of proteins and peptides with the HR spectroscopy.