IR spectra of CS₂ isolated in either a H₂ matrix (bottom panels) or a D₂ matrix (top panels) grown at 3.5 K. Spectra before VUV irradiation (as deposited) and after VUV irradiation are compared. The identified vibrational modes and associated species are discussed in the text. The spectra are vertically shifted for better clarity. The bottom-right inset shows the main IR feature observed, which corresponds to the asymmetric stretching mode of CS₂.