Determination of highest occupied molecular orbital and cationic structures of cyclopentanone using high-resolution vacuum ultraviolet mass-analyzed threshold ionization mass spectrophotometry

초록

The conformational structure of cyclopentanone (CP) and the photoionization dynamics of the corresponding conformer were investigated using the high-resolution vacuum ultraviolet mass-analyzed threshold ionization (MATI) spectroscopic technique. To identify the conformer corresponding to the measured MATI spectrum, the potential energy surfaces associated with the twisting and carbonyl wagging motions in the S-0 and D-0 states were constructed at the B3LYP/cc-pVTZ level, where the twisted conformer in both states corresponded to the global minimum. Furthermore, the Franck-Condon fitting indicated that the cationic conformer had a warped twisted C-1 symmetry rather than C-2 symmetry. This implies that the ionization-induced ring distortion can be principally attributed to the removal of an electron from the highest occupied molecular orbital, which consists of the nonbonding orbital of the oxygen atom in the carbonyl group interacting with the sigma orbitals in the ring of the twisted CP conformer.

키워드