Kwok-leung Yip

Electronic structure of the fluorobenzenes, ethylene, and tetrafluoroethylene

The electronic structures of C6H6‐nFn, 1⩽n⩽6, C2H4, and C2F4 are evaluated by extending the new ’’spectroscopic’’ self‐consistent‐field CNDO/S2 molecular orbital model to include a parameterization of fluorine. As in our earlier studies of conjugated hydrocarbons, the CNDO/S2 model provides an adequate description of photoelectron spectra associated with states of ionization potential I≲13 eV. The intensities of vibrational progressions evident in the photoelectron spectra are analyzed to extract the linear coupling constants of electrons in the various molecular orbitals to the totally symmetric (a1g) molecular vibrations and, when allowed by symmetry, to e2g molecular vibrations. These coupling constants differ substantially from those obtained for benzene and deuterobenzene. Their values reflect the consequences of the heavy fluorine mass and the incompressibility of the charge density on the fluorine substituent. They lead, moreover, to explicit predictions of increased insulating behavior for fluorob...

On the computation of Onsager quantum efficiency

A new method of computing the Onsager quantum efficiency of photogeneration is presented. This method is shown to be much faster than and as accurate as the series method used previously. Results applicable to a‐Si (dielectric constant=11.5) are given as an example.