已为您找到该学者20条结果 成果回收站
郑旭明, Xuming Zheng, David Lee Phillips*
Chemical Physics Letters 316 2000. 524~530,-0001,():
-1年11月30日
We report density functional theory calculation results that examine the ultraviolet electronic transitions of CF2I2 and CH2I2. We make preliminary assignments of several transitions to the ultraviolet absorption spectra of CF2I2 and CH2I2. We compare our present results to previous experimental and computational work. We also examine the molecular orbitals involved in the electronic transitions assigned to the absorption spectra.
-
40浏览
-
0点赞
-
0收藏
-
0分享
-
38下载
-
0
-
引用
郑旭明, Xuming Zheng, David Lee Phillips*
Chemical Physics Letters 286(1998)79~87,-0001,():
-1年11月30日
Resonance Raman spectra of l-chloro-2-iodoethane in cyclohexane solution are presented for three excitation wavelengths. The fundamentals, overtones and combination bands of the nominal CCCI bend (v10), the nominal C I stretch (v9), and the C-C1 stretch (v8) vibrational modes can account for most of the resonance Raman intensity. The resonance Raman spectra and associated short-time photodissociation dynamics of I-chloro-2-iodoethane are compared with iodoethane and this suggests that the chloroethyl radical receives more internal excitation than the ethyl radical from the A-band photodissociation in as much as the initial dynamics determines the internal excitation of the alkyl radical photoproducts.
-
19浏览
-
0点赞
-
0收藏
-
0分享
-
31下载
-
0
-
引用
郑旭明, Xuming Zheng, a), Cheong Wan Lee, Yun-Liang Li, Wei-Hai Fang, b), and David Lee Phillipsc)
J. Chem. Phys., Vol. 113, No.17, 1 November 2000,-0001,():
-1年11月30日
We report transient resonance Raman spectra and density functional theory calculations for the photoproducts produced after ultraviolet excitation of CHBr2Cl and CCl3Br in cyclohexane solution. Comparison of the computed vibrational frequencies to the experimental Raman frequencies revealed that the iso-CHBrCl-Br and iso-CHClBr-Br species are mainly responsible for the transient resonance Raman spectrum observed following ultraviolet excitation of CHBr2Cl. Similar comparisons for CCl3Br showed the iso-CCl2Cl-Br species is mainly responsible for the transient resonance Raman spectrum observed following ultraviolet excitation of CCl3Br. Additional density functional theory computations were done to examine the chemical reactions of iso-CH2Br-Cl and iso-CH2Cl-Br with ethylene to give cyclopropane and Br-Cl product. We briefly discuss the possibility for release of reactive halogens into the atmosphere via the photochemical and chemical reactions of iso-polyhalomethane molecules formed after ultraviolet excitation of polyhalomethanes in condensed phase environments.
-
50浏览
-
0点赞
-
0收藏
-
0分享
-
76下载
-
0
-
引用
【期刊论文】Phase-dependent conformation selection of axial and equatorial forms of iodocyclopentane
郑旭明, Xuming Zheng, David Lee Phillips*
Chemical Physics Letters 307 1999. 350~358,-0001,():
-1年11月30日
We have obtained Raman spectra for neat liquid iodocyclopentane and for two types of solid phases. Ab initio calculations were done to help elucidate the Raman band assignments to either the axial or equatorial conformations of iodocyclopentane. The liquid Raman spectrum displays bands for both axial and equatorial conformations of iodocyclopentane while the two solid phases exhibit a strong preference for either the axial conformation for the annealed solid phase or the equatorial conformation for the unannealed solid phase. We discuss the possible utility for using this phase-dependent conformation selection to examine the conformation dependence of solid-state photochemical reactions.
-
31浏览
-
0点赞
-
0收藏
-
0分享
-
55下载
-
0
-
引用
郑旭明, Xuming Zheng, David Lee Phillips*
Chemical Physics Letters 276(1997)224~232,-0001,():
-1年11月30日
Conformation selective resonance emission spectra are reported for gas-phase iodoeyclohexane with excitation wavelengths of 199.8 and 204.2 nm. These spectra reveal seven Franck-Condon active vibrational modes for the axial conformation and eleven Franck-Condon vibrations for the equatorial conformation, and indicate that the initial dynamics on the B- and C-states have a complex multidimensional character with contributions from the CCC, CCH and HCI bending motions, torsional motions, and C-I, C-C, and C-H stretching motions for both conformations. The resonance emission spectra are generally consistent with the previously reported assignments of the far ultraviolet absorption spectra.
-
49浏览
-
0点赞
-
0收藏
-
0分享
-
97下载
-
0
-
引用