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Intermolecular Hydrogen Bonding Controlled Intersystem Crossing Rates of Benzophenone

Venkatraman, Ravi Kumar and Kayal, Surajit and Barak, Arvind and Orr-Ewing, Andrew J and Umapathy, Siva (2018) Intermolecular Hydrogen Bonding Controlled Intersystem Crossing Rates of Benzophenone. In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 9 (7). pp. 1642-1648.

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Official URL: http://dx.doi.org/ 10.1021/acs.jpclett.8b00345

Abstract

Solvation plays a critical role in various physicochemical and biological processes. Here, the rate of intersystem crossing (ISC) of benzophenone from its S-1(n pi*) state to its triplet manifold of states is shown to be modified by hydrogen-bonding interactions with protic solvent molecules. We selectively photoexcite benzophenone with its carbonyl group either solvent coordinated or uncoordinated by tuning the excitation wavelength to the band center (lambda = 340 nm) or the long-wavelength edge (lambda = 380 nm) of its pi* <- n absorption band. A combination of ultrafast absorption and Raman spectroscopy shows that the hydrogen-bonding interaction increases the time constant for ISC from <200 fs to 1.7 +/- 0.2 ps for benzophenone in CH3OH. The spectroscopic evidence suggests that the preferred pathway for ISC is from the S-1(n pi) to the T-2(pi pi*) state, with the rate of internal conversion from T-2(pi pi*) to T-1(n pi*) controlled by solvent quenching of excess vibrational energy.

Item Type: Journal Article
Additional Information: Copy right for this article belong to AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Depositing User: Id for Latest eprints
Date Deposited: 04 May 2018 18:48
Last Modified: 04 May 2018 18:48
URI: http://eprints.iisc.ac.in/id/eprint/59738

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