F. Brogli, E. Heilbronner, E. Kloster-Jensen
Apr 1, 1974
Citations
0
Influential Citations
57
Citations
Journal
Chemical Physics
Abstract
Abstract Photoelectron spectra of butatriene (I), tetradeuterobutatriene (II), tetramethylbutatriene (III) and tetra- t -butyl- butatriene (IV) are reported and discussed. The four main bands of the spectra of I and II are assigned to ionization from the 1b 3g , 2b 3u , 1b 2u and 1b 2g molecular orbitals on the basis of molecular orbital calculations (ab initio with STO-3G and 4-31G bases and semi-empirical SPINDO) all of which lead to the electron configuration… (1b 2g ) 2 (1b 2u ) 2 (2b 3u ) 2 (1b 3g ) 2 . The first three bands of III and the first two of IV correspond to 2b 3g , 5b 3u , 2b 2u and 7b 3g , 12b 3u molecular orbitals respectively. The spectra of I and II also show an additional band which cannot be assigned to direct ionization of an occupied molecular orbital in the ground state configuration. it is suggested that this may arise from a cation state… (1b 2g ) 2 (1b 2u ) 2 (2b 3u ) 2 (2b 2u ) 2 B 2u . Such a state is correlated with the 2 B 3g cationic ground state by internal rotation but corresponds to a local maximum in the rotational potential. Some simple model calculations are presented of Franck-Condon factors for the internal motion corresponding to these states. These show a composite band of the general type observed. However, the observed vibrational spacings indicate that significant carbon skeletal as well as torsional changes take place on ionization.