IR Dissociation of Weakly Bound Van Der Waals Complexes: (SF₆)_n, (SiF₄)_n, (SiH₄)_n, (C₂H₄)_n, (n=2,3) in the 9–11 μm Range

Abstract

Small (SF₆)_n, (SiF₄)_n, (SiH₄)_n, (C₂H₄)_n (n=2, 3) clusters have been produced in a molecular beam. SF₆ and SiF₄ dimer dissociation spectra were measured and spectral features due to clusters containing different S and Si isotopes could be resolved. The contribution of trimers could be estimated in case of SF₆ Dissociation spectra of small SiH₄ clusters were measured for the first time in the frequency range 880 cm-¹ - 940 cm-¹. In the dissociation spectra of ethylene clusters van der Waals modes coupled with the out of plane V₇ C₂H₄ vibration have been observed for the dimer, and a long pre-dissociation lifetime (15 ns) has been inferred from the observed narrow (FWHM = 10 MHz) rotational lines.