Yoon Sangwoon, McCamant David W, Kukura Philipp, Mathies Richard A, Zhang Donghui, Lee Soo-Y
Department of Chemistry, University of California, Berkeley, California 94720, USA.
J Chem Phys. 2005 Jan 8;122(2):024505. doi: 10.1063/1.1828044.
The effect of the time delay between the picosecond Raman pump and the femtosecond Stokes probe pulse on the Raman gain line shape in femtosecond broadband stimulated Raman spectroscopy (FSRS) is presented. Experimental data are obtained for cyclohexane to investigate the dependence of the FSRS line shape on this time delay. Theoretical simulations of the line shapes as a function of the time delay using the coupled wave theory agree well with experimental data, recovering broad line shapes at positive time delays and narrower bands with small Raman loss side wings at negative time delays. The analysis yields the lower bounds of the vibrational dephasing times of 2.0 ps and 0.65 ps for the 802 and 1027 cm(-1) modes for cyclohexane, respectively. The theoretical description and simulation using the coupled wave theory are also consistent with the observed Raman gain intensity profile over time delay, reaching the maximum at a slightly negative time delay (approximately -1 ps), and show that the coupled wave theory is a good model for describing FSRS.
本文介绍了皮秒拉曼泵浦脉冲与飞秒斯托克斯探测脉冲之间的时间延迟对飞秒宽带受激拉曼光谱（FSRS）中拉曼增益线形的影响。通过对环己烷进行实验，获得了FSRS线形与该时间延迟之间关系的实验数据。利用耦合波理论对线形作为时间延迟函数进行的理论模拟与实验数据吻合良好，在正时间延迟时恢复为宽线形，在负时间延迟时为具有小拉曼损耗侧翼的较窄谱带。分析得出环己烷802和1027 cm(-1)模式的振动退相时间下限分别为2.0 ps和0.65 ps。使用耦合波理论进行的理论描述和模拟也与观察到的拉曼增益强度随时间延迟的分布一致，在略负的时间延迟（约 -1 ps）处达到最大值，表明耦合波理论是描述FSRS的良好模型。
