Dynamics of Electronically Excited States in the Eumelanin Building Block 5,6-Dihydroxyindole
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.
MSU Digital Commons Citation
Crane, Stuart W.; Ghafur, Omair; Cowie, Thomas Y.; Lindsay, Anita G.; Thompson, James O.F.; Greenwood, Jason B.; Bebbington, Magnus; and Townsend, Dave, "Dynamics of Electronically Excited States in the Eumelanin Building Block 5,6-Dihydroxyindole" (2019). Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works. 515.