Geometric phase effects in the coherent control of the branching ratio of photodissociation products of phenol

Journal Article · Wed Jun 14 04:00:00 EDT 2006 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.2203611· OSTI ID:20783302

Abe, Mayumi; Ohtsuki, Yukiyoshi; Fujimura, Yuichi; Lan, Zhenggang; Domcke, Wolfgang ^[1]

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1. Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan)

Optimal control simulation is used to examine the control mechanisms in the photodissociation of phenol within a two-dimensional, three-electronic-state model with two conical intersections. This model has two channels for H-atom elimination, which correspond to the {sup 2}{pi} and {sup 2}{sigma} states of the phenoxyl radical. The optimal pulse that enhances {sup 2}{sigma} dissociation initially generates a wave packet on the S{sub 1} potential-energy surface of phenol. This wave packet is bifurcated at the S{sub 2}-S{sub 1} conical intersection into two components with opposite phases because of the geometric phase effect. The destructive interference caused by the geometric phase effect reduces the population around the S{sub 1}-S{sub 0} conical intersection, which in turn suppresses nonadiabatic transitions and thus enhances dissociation to the {sup 2}{sigma} limit. The optimal pulse that enhances S{sub 0} dissociation, on the other hand, creates a wave packet on the S{sub 2} potential-energy surface of phenol via an intensity borrowing mechanism, thus avoiding geometric phase effects at the S{sub 2}-S{sub 1} conical intersection. This wave packet hits the S{sub 1}-S{sub 0} conical intersection directly, resulting in preferred dissociation to the {sup 2}{pi} limit. The optimal pulse that initially prepares the wave packet on the S{sub 1} potential-energy surface (PES) has a higher carrier frequency than the pulse that prepares the wave packet on the S{sub 2} PES. This counterintuitive effect is explained by the energy-level structure and the S{sub 2}-S{sub 1} vibronic coupling mechanism.

• OSTI ID: 20783302
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 22 Vol. 124; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
BRANCHING RATIO
DISSOCIATION
ENERGY LEVELS
PHENOL
PHOTOLYSIS
REACTION KINETICS
SIMULATION
TWO-DIMENSIONAL CALCULATIONS
WAVE PACKETS