Raman spectra of <scp>L</scp>‐histidine hydrochloride monohydrate crystal

Abstract

Abstract Single‐crystal samples of L ‐histidine hydrochloride monohydrate (LHICL), C 6 H 9 N 3 O 2 ·HCl·H 2 O, were studied by Raman spectroscopy at temperatures ranging from 295 to 40 K over the spectral range 20–3400 cm −1 . A tentative assignment of the bands is given. The effect of temperature change on the vibrational spectrum is discussed. The behavior of the Raman spectra, in particular the emergence of new modes in the low‐wavenumber region, indicates that LHICL undergoes a structural phase transition between 140 and 110 K. There are further indications that, possibly, a second change of structure occurs for temperatures between 80 and 60 K. Copyright © 2004 John Wiley &amp; Sons, Ltd.