Kukura Philipp, McCamant David W, Mathies Richard A
Department of Chemistry University of California, Berkeley, California 94720.
J Phys Chem A. 2004 Jul 15;108(28):5921-5. doi: 10.1021/jp0482971.
The electronic and vibrational structure of beta-carotene's early excited states are examined using femtosecond time-resolved stimulated Raman spectroscopy. The vibrational spectrum of the short-lived ( approximately 160 fs) second excited singlet state (S(2),1B(u) (+))of beta-carotene is obtained. Broad, resonantly enhanced vibrational features are observed at approximately 1100, 1300, and 1650 cm(-1) that decay with a time constant corresponding to the electronic lifetime of S(2). The temporal evolution of the vibrational spectra are consistent with significant population of only two low-lying excited electronic states (1B(u) (+) and 2A(g) (-)) in the ultrafast relaxation pathway of beta-carotene.
利用飞秒时间分辨受激拉曼光谱研究了β-胡萝卜素早期激发态的电子结构和振动结构。获得了β-胡萝卜素短寿命（约160飞秒）的第二激发单重态（S(2)，1B(u)(+)）的振动光谱。在约1100、1300和1650 cm(-1)处观察到宽的、共振增强的振动特征，其衰减时间常数与S(2)的电子寿命相对应。振动光谱的时间演化与β-胡萝卜素超快弛豫途径中仅两个低激发电子态（1B(u)(+)和2A(g)(-)）的大量布居一致。
