A combined experimental/theoretical investigation of the He + ICl interactions: Determination of the binding energies of the T-shaped and linear He⋯I35Cl(X,ν″ = 0) conformers

David S. Boucher, Joshua P. Darr, Matthew D. Bradke, Richard A. Loomis, Anne B. McCoy

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Abstract

A simple model based on the assumption of a thermodynamic equilibrium between the populations of the T-shaped and linear He⋯I 35Cl(X,ν″ = 0) complexes stabilized in a supersonic expansion is utilized to estimate the relative binding energies of the ground state conformers. In this model, the relative intensities of the laser-induced fluorescence features, attributed to transitions of each conformer, are used to track changes in the populations along the expansion. The relative intensities of the features and the I35Cl(X,ν″ = 0) rotational temperatures measured at each distance are fit to ratios of the quantum mechanical partition functions for the T-shaped and linear complexes. These are used to determine the difference between the binding energies of the two conformers. The linear He⋯I35Cl(X,ν″ = 0) complex is estimated to be 2.5(6) cm-1 more strongly bound than the T-shaped conformer. The validity of this model was in part confirmed by performing the analysis on calculated ro-vibronic spectra of He⋯I35Cl, where the J″ = 0 binding energies of the ground state conformers are known. The results from high-resolution action and two-color pump-probe spectroscopy experiments reveal that the binding energy of the linear He⋯I 35Cl(X,ν″ = 0) conformer is precisely 22.0(2) cm -1. The binding energy of the T-shaped He⋯I 35Cl(X,ν″ = 0) conformer is then 19.5(6) cm-1.

Original languageEnglish (US)
Pages (from-to)5275-5282
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume6
Issue number23
DOIs
StatePublished - Dec 7 2004

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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