Transient second harmonic generation from oxazine dyes at the air/water interface
Transient second harmonic generation from oxazine dyes at the air/water interface
复制标题
恶嗪染料在空气/水界面处产生瞬态二次谐波
DOI：
10.1021/jp013360x
复制
发表时间：
2002
影响因子：
3.3
通讯作者：
J. Owrutsky
中科院分区：
文献类型：
--
作者：
D. Steinhurst;A. Baronavski;J. Owrutsky
报道了几种恶嗪染料在空气/水界面上的超快表面二次谐波产生（SHG）研究。正如我们先前在恶嗪染料水溶液的稳态SHG研究中所证明的[J. Phys. Chem. B 2001，105，3062]，SHG信号几乎完全是由于二聚体。瞬态SHG恢复是双指数的，时间常数为4 - 8 ps和22 - 44 ps，取决于染料和溶液成分。倍频恢复是单光子共振的，归因于两个平行的基态恢复机制。瞬态吸收信号也测量了大量的染料溶液的水和甲醇，结果表明，快速（2 ps）的溶剂化动力学组件，以及由于激发态寿命（>400 ps）的染料单体的较长的组件。因此，在表面处观察到的染料的衰减时间与本体溶液中观察到的衰减时间不同，并且它们类似于先前报道的染料聚集体。
Ultrafast surface second harmonic generation (SHG) studies are reported for several oxazine dyes at the air/water interface. As we demonstrated previously [J. Phys. Chem. B 2001, 105, 3062] in our steady-state SHG studies of aqueous oxazine dye solutions, the SHG signals are almost entirely due to dimers. The transient SHG recovery is biexponential with time constants of 4−8 ps and 22−44 ps depending on the dye and the solution composition. The SHG recovery is one-photon resonant and is attributed to two parallel ground state recovery mechanisms. Transient absorption signals were also measured for bulk dye solutions of water and methanol, and the results indicate a fast (2 ps) solvation dynamics component as well as a longer component due to the excited state lifetime (>400 ps) of the dye monomer. Therefore, both decay times observed for the dyes at the surface are different than what is seen for bulk solution, and they resemble what has been previously reported for dye aggregates.