Autoregressive vibrational-dephasing analysis of the ν2 band of liquid methyl iodide in nanoporous glass

The spontaneous Raman spectrum of the ν2 methyl-deformation mode of liquid methyl iodide confined in 50-Å-diameter pores of silica sol–gel glass was measured at room temperature. The ν2 band was broader for the microconfined liquid than for the bulk liquid. Vibrational correlation functions obtained by Fourier transforming the isotropic bands were modeled by using a memory-function procedure based on the Zwanzig–Mori formalism. The memory functions were analyzed by stochastic time series using an autoregressive model. Based on this analysis, the increase in the line width is largely attributed to inhomogeneous broadening due to site inhomogeneities at the pore surface.