Supersonic molecular jet studies of toluene–helium and toluene–methane clusters

Abstract

The techniques of fluorescence excitation (FE), dispersed emission (DE), and one‐ and two‐color time of flight mass spectroscopy (TOFMS) have been employed to study van der Waals clusters of toluene–helium (TolHe) and toluene–methane (TolCH₄) formed in a supersonic molecular jet. Spectral shifts for the toluene ¹B₂←¹A₁ transition have been characterized for TolHe_1,2 and Tol(CH₄)_1,2. The van der Waals stretching frequencies (V¹) in the excited states of these clusters have been identified. The ground state stretch (V₁) for TolHe has also been found; it is quite similar to the TolHe V¹. The binding energies (D₀) for Tol–He clusters lie between 75 and 90 cm⁻¹ and those for Tol–CH₄ clusters lie between 533 and 739 cm⁻¹. The coordination of a third solvent molecule to those clusters generates a broad spectrum whose shift is close to the limiting value for a large (x>3) cluster. A comparison between these data and methane solution data is presented.