Kang H, Jouvet C, Dedonder-Lardeux C, Martrenchard S, Grégoire G, Desfrançois C, Schermann J P, Barat M, Fayeton J A
Laboratoire de Photophysique Moléculaire du CNRS, Université Paris-Sud, Bât. 210, 91405 Orsay, France.
Phys Chem Chem Phys. 2005 Jan 21;7(2):394-8. doi: 10.1039/b414986f.
Deactivation pathways of electronically excited states have been investigated in three protonated aromatic amino acids: tryptophan (Trp), tyrosine (Tyr) and phenylalanine (Phe). The protonated amino acids were generated by electrospray and excited with a 266 nm femtosecond laser, the subsequent decay of the excited states being monitored through fragmentation of the ions induced and/or enhanced by another femtosecond pulse at 800 nm. The excited state of TrpH+ decays in 380 fs and gives rise to two channels: hydrogen atom dissociation or internal conversion (IC). In TyrH, the decay is slowed down to 22.3 ps and the fragmentation efficiency of PheH+ is so low that the decay cannot be measured with the available laser. The variation of the excited state lifetime between TrpH+ and TyrH+ can be ascribed to energy differences between the dissociative pi sigma* state and the initially excited pi pi* state.
色氨酸（Trp）、酪氨酸（Tyr）和苯丙氨酸（Phe）的电子激发态失活途径进行了研究。质子化氨基酸通过电喷雾产生，并用266 nm飞秒激光激发，激发态随后的衰变通过由800 nm另一个飞秒脉冲诱导和/或增强的离子碎片化进行监测。TrpH⁺的激发态在380 fs内衰变，并产生两个通道：氢原子解离或内转换（IC）。在TyrH中，衰变减慢至22.3 ps，而PheH⁺的碎片化效率非常低，以至于无法用现有的激光测量其衰变。TrpH⁺和TyrH⁺之间激发态寿命的变化可归因于解离性πσ态与初始激发的ππ态之间的能量差异。
