Rotation-tunneling analysis of proton-transfer dynamics in electronically excited 6-hydroxy-2-formylfulvene using degenerate four-wave mixing

Vealey, Zachary

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https://hdl.handle.net/2142/100809 Copy

Description

Title

Rotation-tunneling analysis of proton-transfer dynamics in electronically excited 6-hydroxy-2-formylfulvene using degenerate four-wave mixing

Author(s)

Vealey, Zachary

Contributor(s)

• Vaccaro, Patrick
• Foguel, Lidor

Issue Date

2018-06-21

Keyword(s)

Electronic structure, potential energy surfaces

Abstract

The multidimensional nature of classically hindered proton transfer is demonstrated clearly by the pronounced effects engendered by attendant electronic and vibrational degrees of freedom, the selective excitation of which can enhance or diminsh the rate of hydron migration greatly. To explore the provenance of such phenomena, the origin band (00 0 ) of the A˜1B2–X˜ 1A1 absorption system in 6-hydroxy-2-formylfulvene (HFF) has been probed under ambient bulk-gas conditions by using polarization-resolved degenerate four-wave mixing (DFWM) spectroscopy. The alleviation of rovibronic congestion and suppression of rotational-branch structure afforded by judicious selection of incident/detected polarizations for the DFWM interaction has enabled refined rotation-tunneling information to be extracted for the lowest-lying singlet excited manifold, A˜1B2 (π*π). In contrast to the ultrafast dynamics (τ pt≤120fs) that characterize the X˜ 1A1 ground electronic state of HFF, the π*←π electron promotion is found to impede intramolecular proton transfer markedly, leading to the near complete quenching of tunneling-induced spectral signatures. The intrinsic dependence of reaction coordinate and proton-transfer efficacy on the nuances of potential-surface topology and transition-state geometry will be discussed in light of these experimental results, with complementary quantum-chemical calculations serving to elucidate the dramatic impact that subtle changes in energy landscape can exert upon unimolecular dynamics.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100809

DOI

10.15278/isms.2018.RJ01

Copyright and License Information

Copyright 2018 Zachary Vealey

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