Issue 15, 2019

Dynamics of electronically excited states in the eumelanin building block 5,6-dihydroxyindole

Abstract

We report the first excited state dynamics study of gas-phase 5,6-dihydroxyindole (5,6-DHI), a key building block of eumelanin pigments that are found throughout nature and serve as important photo-protective compounds. Time-resolved ion-yield measurements over the 241–296 nm ultraviolet photoexcitation region revealed non-adiabatic processes occurring on up to three distinct timescales. These reflect ultrafast (i.e. sub-picosecond) internal conversion within the excited state singlet manifold, and much longer-lived processes ranging from 10 ps to in excess of 1 ns. Our investigation paves the way for precisely targeted future studies of 5,6-DHI that exploit more differential measurement techniques. The work was facilitated by the use of soft laser-based thermal desorption to introduce 5,6-DHI samples into the gas phase. This approach, based on low-cost, readily available diode lasers, is straightforward, easily controllable and potentially applicable to a wide range of non-volatile molecular species.

Graphical abstract: Dynamics of electronically excited states in the eumelanin building block 5,6-dihydroxyindole

Supplementary files

Article information

Article type
Paper
Submitted
31 Jan 2019
Accepted
27 Mar 2019
First published
01 Apr 2019

Phys. Chem. Chem. Phys., 2019,21, 8152-8160

Dynamics of electronically excited states in the eumelanin building block 5,6-dihydroxyindole

S. W. Crane, O. Ghafur, T. Y. Cowie, A. G. Lindsay, J. O. F. Thompson, J. B. Greenwood, M. W. P. Bebbington and D. Townsend, Phys. Chem. Chem. Phys., 2019, 21, 8152 DOI: 10.1039/C9CP00620F

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