Ultrafast Vibrational Relaxation Dynamics of C=O and C=C Stretching Modes of Ethyl Acetoacetate in Deuterated Water and Cyclohexane

doi:10.6023/A13020166

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	Ultrafast Vibrational Relaxation Dynamics of C=O and C=C Stretching Modes of Ethyl Acetoacetate in Deuterated Water and Cyclohexane
	Liu Yingliang; Yang Fan; Wang Jianping
刊名	ACTA CHIMICA SINICA
	2013-05-15
卷号	71 期号:5 页码:761-768
关键词	Ir Pump-probe Vibrational Energy Relaxation Dynamics Anisotropy Dynamics Ethyl Acetoacetate
ISSN号	0567-7351
DOI	10.6023/A13020166
英文摘要	As a prototype of both beta-diketone and alpha,beta-enone compounds, ethyl acetoacetate (EAC) has been known to exist in multiple structures in solutions. In this paper, femtosecond infrared pump-probe spectroscopy was used to examine the vibrational relaxation processes of the C=O and C=C stretching modes, appeared in the region of 6 p,m wavelength (1600 similar to 1800 cm(-1) in frequency), of the EAC tautomers in deuterated water (D2O) and cyclohexane. Steady-state infrared spectroscopy and quantum chemistry computations were used to understand the characteristics of these vibrational bands and their line shapes. The results showed that in water EAC exists in the keto form, while in cyclohexane it exists in both keto and enol forms, and perhaps in two possible keto forms. As a result of structural rigidity, the steady-state infrared absorption peak is narrow for the enol form, suggesting mainly homogenous broadening; while those of the keto form exhibit the feature of both homogenous and heterogeneous broadenings. The apparent infrared line shapes of the keto and enol forms were somewhat different even in the same solvent. Population dynamics and anisotropy dynamics of the C=O and C=C stretching mode were obtained and examined by transient infrared pump-probe measurement. In D2O, the vibrational energy relaxation rate of the C=O modes was found to be faster than that in cyclohexane, which can be attributed to the formation hydrogen bond between EAC and solvent molecules. The vibrational relaxation process of the enol form was found to be different from that of the keto form, which can be contributed to Fermi resonance interaction between the C=O stretching mode and the COH bending mode. With the aid of the quantum chemistry calculations, it is concluded that there exists a fast vibrational population equilibrium process between the C=O and C=C stretching modes and the COH in-plane bending mode via Fermi resonance. Anisotropy experiments showed a fast orientation dynamics for EAC in cyclohexane than in water, reflecting different solvations. Further, quantum beating was observed in the anisotropy dynamics due to the coherence between the ss- and as-modes, especially for the keto form, suggesting a coherent excitation between the related vibrational modes.
语种	英语
出版者	SCIENCE PRESS
WOS记录号	WOS:000320011200012
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/42060]
专题	中国科学院化学研究所
通讯作者	Liu Yingliang
作者单位	Chinese Acad Sci, Inst Chem, Mol React Dynam Lab, Beijing Natl Lab Mol Sci, Beijing 100190, Peoples R China
推荐引用方式 GB/T 7714	Liu Yingliang,Yang Fan,Wang Jianping. Ultrafast Vibrational Relaxation Dynamics of C=O and C=C Stretching Modes of Ethyl Acetoacetate in Deuterated Water and Cyclohexane[J]. ACTA CHIMICA SINICA,2013,71(5):761-768.
APA	Liu Yingliang,Yang Fan,&Wang Jianping.(2013).Ultrafast Vibrational Relaxation Dynamics of C=O and C=C Stretching Modes of Ethyl Acetoacetate in Deuterated Water and Cyclohexane.ACTA CHIMICA SINICA,71(5),761-768.
MLA	Liu Yingliang,et al."Ultrafast Vibrational Relaxation Dynamics of C=O and C=C Stretching Modes of Ethyl Acetoacetate in Deuterated Water and Cyclohexane".ACTA CHIMICA SINICA 71.5(2013):761-768.