Effects of Deuteration on Proton Tunneling Modes and Coupled Optic Modes in the Raman Spectrum of KDP Crystals

Abstract

Raman spectrum was studied for several KH 2(1- x ) D 2 x PO 4 crystals with 0< x <0.85. Effects of deuteration were seen in spectra of collective tunneling modes and optical modes coupled to them. Below T c , in the B 2 modes spectra for large x , a distinct narrowing of the width of a mode (ω + =210 cm -1 ) was observed in addition to the expected extinction of the soft mode (ω - =140 cm -1 ). In the E-mode spectra, a sharp mode at 113 cm -1 and a broad Rayleigh wing were also found to be sensitive to the deuteration.