Influence of the cooling rate on low-temperature Raman and infrared-reflection spectra of partially deuterated κ-(BEDT-TTF)2Cu(N(CN)2)Br

Raman and infrared-reflection spectra of κ-(BEDT-TTF)2Cu(N(CN)2)Br and its deuterated and partially deuterated analogues were measured at temperatures between 5 and 300 K and cooling rates from 1 to 20 K/min. It was found that, in partially deuterated samples, the interdimer electron-molecular vibration splitting of ν3 mode in Raman spectra, and linewidths of some phonon peaks both in Raman and infrared spectra depend on the cooling rate. These observations were explained by disorder-related effects.