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Mechanisms for ultrafast nonradiative relaxation in electronically excited eumelanin constituents.


ABSTRACT: We investigate the relaxation dynamics of melanin model constituents including monomers, dimers, and tetramers, upon excitation, using state-of-the-art, time-dependent, density functional theory calculations. The results explain the ability of these molecules to transform photon energy into thermal energy in a remarkably short timescale of approximately 100 fs. We find that after electronic excitation by light absorption, ultrafast energy conversion takes place through two novel mechanisms: proton transfer on a timescale of 110 fs and state mixing upon oligomerization on a timescale of <50 fs. These results are in good agreement with available experiments and help elucidate melanin's role in photoprotection against ultraviolet radiation.

SUBMITTER: Meng S 

PROVIDER: S-EPMC2567931 | biostudies-literature | 2008 Nov

REPOSITORIES: biostudies-literature

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Mechanisms for ultrafast nonradiative relaxation in electronically excited eumelanin constituents.

Meng Sheng S   Kaxiras Efthimios E  

Biophysical journal 20080801 9


We investigate the relaxation dynamics of melanin model constituents including monomers, dimers, and tetramers, upon excitation, using state-of-the-art, time-dependent, density functional theory calculations. The results explain the ability of these molecules to transform photon energy into thermal energy in a remarkably short timescale of approximately 100 fs. We find that after electronic excitation by light absorption, ultrafast energy conversion takes place through two novel mechanisms: prot  ...[more]

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