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Ultrafast dynamics of aniline in the 294-234 nm excitation range: the role of the πσ∗ state

Authors :
Alvaro Peralta Conde
Asier Longarte
Fernando Castaño
Raúl Montero
Roberto Fernandez Martinez
Virginia Ovejas
Source :
The Journal of chemical physics. 135(5)
Publication Year :
2011

Abstract

The ultrafast relaxation of jet-cooled aniline was followed by time-resolved ionization, after excitation in the 294-234 interval. The studied range of energy covers the absorption of the two bright ππ∗ excitations, S(1) and S(3), and the almost dark S(2) (πσ∗) state. The employed probe wavelengths permit to identify different ultrafast time constants related with the coupling of the involved electronic surfaces. A τ(1) = 165 ± 30 fs lifetime is attributed to dynamics along the S(2) (πσ∗) repulsive surface. Other relaxation channels as the S(1)→S(0) and S(3)→S(1) internal conversion are also identified and characterized. The work provides a general view of the photophysics of aniline, particularly regarding the role of the πσ∗ state. This state appears as minor dissipation process due to the ineffective coupling with the bright S(1) and S(3) states, being the S(1)→S(0) internal conversion the main non-radiative process in the full studied energy range. Additionally, the influence of the off-resonance adiabatic excitation of higher energy electronic states, particularly S(3), is also observed and discussed.

Details

ISSN :
10897690
Volume :
135
Issue :
5
Database :
OpenAIRE
Journal :
The Journal of chemical physics
Accession number :
edsair.doi.dedup.....1ea063cf661f34b17727ebd7756f3783