Quantum calculations of the polarized emission spectrum of methyl iodide: The importance of interference effects.

Autor: Wedlock, Michael R., Freed, Karl F.
Předmět:
Zdroj: Journal of Chemical Physics; 11/15/1991, Vol. 95 Issue 10, p7275, 11p
Abstrakt: We present detailed quantum calculations of the polarized emission spectrum from methyl iodide after excitation at 266 nm. Methyl iodide has two dipole accessible and mutually coupled repulsive electronic surfaces at this excitation energy. Thus it is expected that there are interference contributions to the angularly resolved polarized emission spectrum. Using a one-dimensional model and time-independent quantum computations of the emission into ground state C–I overtone vibrations, these interference contributions are shown to significantly influence the polarized emission spectrum and, for example, to produce a counterintuitive dependence on final state overtone number. The calculations demonstrate that the influence of the interference terms is enhanced by the formation of polarized emission intensity ratios because of the differing signs of geometric coefficients associated with the interference terms. We also study the effect of varying the strength of the coupling potential and the range over which it acts. The nonintuitive nature of the interference terms and the amplification of their influence by the formation of polarized emission intensity ratios demonstrate why quantum computations are important for a complete understanding of the polarized emission spectroscopy experiment for methyl iodide. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index