P. Breen, J. Warren, E. Bernstein
Aug 15, 1987
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0
Influential Citations
34
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Journal
Journal of Chemical Physics
Abstract
Dispersed emission (DE) and time of flight mass spectra (TOFMS) are presented for supersonic molecular jet‐cooled o‐, m‐, and p‐n‐propyltoluene. The spectra exhibit multiple origins which are assigned to anti and gauche conformations of the propyl group relative to the aromatic ring. The TOFMS of m‐n‐propyltoluene rules out an eclipsed propyl conformation as a populated conformation. Empirical force field (EFF) calculations are presented which support these assignments. The spectra also exhibit features, typically within 100 cm−1 of the origin, which are assigned to transitions associated with the internal rotation of the ring methyl group. A model which treats this methyl motion as a one‐dimensional rigid rotor is used to solve for the rotational constant B of the methyl rotor, and for the size and shape of the barrier to rotation. The barrier for p‐n‐propyltoluene is found to be small in both the ground (S0−V6=5 cm−1) and excited (S1−V6=20 cm−1) electronic states. For m‐n‐propyltoluene, the ground state...