In:
The Journal of Chemical Physics, AIP Publishing, Vol. 137, No. 19 ( 2012-11-21)
Abstract:
In a previous study [T. Horio, T. Fuji, Y.-I. Suzuki, and T. Suzuki, J. Am. Chem. Soc. 131, 10392 (2009)10.1021/ja904780b], we demonstrated that the time–energy map of photoelectron angular anisotropy enables unambiguous identification of ultrafast S2(ππ*)–S1(nπ*) internal conversion in pyrazine. A notable characteristic of this map is that the forbidden ionization process of D0(n−1) ← S2(ππ*) gives a negative photoelectron anisotropy parameter. In the present study, we elucidate the mechanism of this process by calculating the photoionization transition dipole moments and photoelectron angular distribution using the first-order configuration interaction method and the continuum multiple scattering Xα approximation; these calculations at the S0 equilibrium geometry reproduce the observed anisotropy parameters for D0 ← S2 and D0 ← S1 ionizations, respectively. On the other hand, they do not reproduce the small difference in the photoelectron anisotropy parameters for the D1(π−1) ← S2 and D0 ← S1 ionizations, both of which correspond to removal of an electron from the same π* orbital in the excited states. We show that these ionizations are affected by the kag shape resonance and that the difference between their photoelectron anisotropy parameters originates from the difference in the molecular geometry in D1 ← S2 and D0 ← S1.
Type of Medium:
Online Resource
ISSN:
0021-9606
,
1089-7690
Language:
English
Publisher:
AIP Publishing
Publication Date:
2012
detail.hit.zdb_id:
3113-6
detail.hit.zdb_id:
1473050-9
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