Caging of vibrational energy transfer and interactions in binary mixed solvents probed from Raman scattering linewidth

Abstract

The research focuses on Raman effects from vibrational interactions for mixed solute and solvent in binary mixed liquid for vibrational exchange from anharmonic interactions from three and four body collisions of mixed solvents from shields and cages about excited molecule of solute. The Raman linewidth were measured and theoretically fitted by varying the mole fraction (X) of solute proportions with mixed solvents, one acting as a solute and the other as a solvent. The excitation of CH3 modes to the daughter modes and other mixed molecule modes show the effect of anharmonic many body collisions, dephasing and vibrational energy transfer. The Raman linewidth and intensity of the higher vibrational modes of solvents: Acetone and Methanol can rise in the presence of a second solvent of lower vibrational modes act as shield. Using various combinations of the solvents as acetone and methanol with carbon disulfide, and carbon tetrachloride can alter relaxation pathways due to the interruption of intermolecular energy decay routes of acetone and methanol by the low energy modes of carbon tetrachloride and carbon disulfide act as shields to energy transfer. Carbon tetrachloride is a stronger shielding agent than carbon disulfide for both acetone’s high and low energy modes due to acetone’s larger amphiphilic structure that is more resilient to structural hindrance of the linear carbon disulfide as opposed to the larger spherical carbon tetrachloride. Carbon disulfide is a stronger shielding agent than carbon tetrachloride for methanol except in the case of 1456 cm−1 energy mode due to the increased structural hindrance of carbon disulfide’s linear structure, which methanol is more susceptible to by its smaller molecular structure, preventing intermolecular interactions with other methanol molecules.