Mechanisms for Ultrafast Nonradiative Relaxation in Electronically Excited Eumelanin Constituents

被引:43
|
作者
Meng, Sheng
Kaxiras, Efthimios [1 ]
机构
[1] Harvard Univ, Dept Phys, Cambridge, MA 02138 USA
关键词
D O I
10.1529/biophysj.108.135756
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
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 similar to 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.
引用
收藏
页码:4396 / 4402
页数:7
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