Spectral Signatures of Ground- and Excited-State Wavepacket Interference after Impulsive Excitation
Spectral Signatures of Ground- and Excited-State Wavepacket Interference after Impulsive Excitation
复制标题
DOI：
10.1021/acs.jpca.0c03912
复制
发表时间：
2020-08-27
影响因子：
2.9
通讯作者：
Levis, Robert J.
中科院分区：
文献类型：
--
作者：
Fitzpatrick, Colin;Odhner, Johanan H.;Levis, Robert J.
利用脉冲瞬态吸收光谱技术研究了不同激发条件下甲酚紫高氯酸盐分子振动相干态的形成和演化。共振和非共振泵浦脉冲导致激发（S-1）和基态（S-0）波包的选择性形成。部分共振和宽带激发条件导致在基态和激发态同时形成波包。波包的特征在于与穿过吸收和发射最大值的波包运动相关联的相干信号中的相位翻转以及与基态波包相比激发态的拉曼特征中的2-10 cm（-1）的红移。我们观察到，当波包被同时激发在地面和激发态表面上，在两个波包的相干振荡之间的皮秒时间尺度上的干扰引起的功能，不能归因于通过一个圆锥形的交叉点，如相移翻转和零振幅节点的波包的通道。使用窗口傅立叶变换的波包滤波突出了这些干扰效应，并表明必须特别小心，以便正确解释以这种方式处理的数据。
Impulsive transient absorption spectroscopy is used to track the formation and evolution of vibrational coherences in cresyl violet perchlorate under different excitation conditions. Resonant and off-resonant pump pulses result in the selective formation of excited (S-1)- and ground (S-0)-state wavepackets. Partially resonant and broadband excitation conditions lead to the simultaneous formation of wavepackets in the ground and excited states. The wavepackets are characterized by the phase-flips in the coherent signal associated with wavepacket motion across the absorption and emission maxima and by a red shift of 2-10 cm(-1) in the Raman features of the excited state compared to the ground-state wavepacket. We observe that, when wavepackets are simultaneously excited on the ground- and excited-state surfaces, interference on a picosecond timescale between coherent oscillations in the two wavepackets gives rise to features that cannot be attributed to the passage of a wavepacket through a conical intersection, such as shifting phase-flips and zero-amplitude nodes. Wavepacket filtering using windowed Fourier transforms highlights these interference effects and demonstrates that special care must be taken in order to properly interpret data that have been processed in this manner.