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Wavelength-dependent Photodissociation Dynamics of Benzaldehyde
刘本康,王丙星,王艳秋,王利*
作者单位E-mail
刘本康 中国科学院大连化学物理研究所分子反应动力学国家重点实验室大连116023中国科学院研究生院北京100049  
王丙星 中国科学院大连化学物理研究所分子反应动力学国家重点实验室大连116023中国科学院研究生院北京100049  
王艳秋 中国科学院大连化学物理研究所分子反应动力学国家重点实验室大连116023  
王利* 中国科学院大连化学物理研究所分子反应动力学国家重点实验室大连116023 liwangye@dicp.ac.cn 
摘要:
利用飞秒泵浦-探测方法结合飞行时间质谱研究了苯甲醛在不同泵浦波长260、271、284和287 nm下的超快动力学. 在S2区(λ<284 nm),受激分子首先经过内转换过程到S1高振动态,实验观察到这个过程随着S2态分子振动能量的增加而变快,可能源于高振动能级密度导致S2与S1之间内转换加快. 双指数拟合的第二个过程(约600 fs)认为可能是由于内转换后在S1态发生的振动
关键词:  苯甲醛,超快过程,飞秒泵浦
DOI:10.1088/1674-0068/22/06/587-591
分类号:
基金项目:
Wavelength-dependent Photodissociation Dynamics of Benzaldehyde
Ben-kang Liu,Bing-xing Wang,Yan-qiu Wang,Li Wang*
Abstract:
The ultrafast dynamics of benzaldehyde upon 260, 271, 284, and 287 nm excitations have been studied by femtosecond pump-probe time-of-flight mass spectrometry. A biexponential decay component model was applied to fit the transient profiles of benzaldehyde ions and fragment ions. At the S2 origin, the first decay of the component was attributed to the internal conversion to the high vibrational levels of S1 state. Lifetimes of the first component decreased with increasing vibrational energy, due to the influence of high density of the vibrational levels. The second decay was assigned to the vibrational relaxation of the S1 whose lifetime was about 600 fs. Upon 287 nm excitation, the first decay became ultra-short (~56 fs) which was taken for the intersystem cross from S1 to T2, while the second decay component was attributed to the vibrational relaxation. The pump-probe transient of fragment was also studied with the different probe intensity at 284 nm pump.
Key words:  Benzaldehyde, Ultrafast process, Femtosecond pump-probe