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Chinese Journal of Chemical Physics 2017年第2期30卷 123-127,I0001页

作者：茆锐何超陈旻周丹娜张群陈旸常州工学院数理与化工学院常州213032 中国科学技术大季化学物理系合肥微尺度物质科学国家实验室(筹)合肥230026

We report on the photodissociation dynamics of CO2^＋ via its A2Пu,1/2 state using the scheme of [1＋1] photon excitation that is intermediated by the mode-selected A2Hu,1/2（Vl,V2,0） vibronic states. photodissociation fragment exciation spectrum and images of photofragment CO＋ have been measured to obtain reaction dynamics parameters such as the available energy and the average translational energy. Combining with the potential energy functions of CO2^＋, the dissociation mechanism of CO2^＋ is discussed. The conformational variation of CO2^＋ from linear to bent on the photodissociation dynamics of CO2^＋ is verified.

关键词： photodissociation dynamics Velocity map imaging Carbon dioxide cation

photodissociation dynamics of Methanol and Ethanol at 157 nm

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Chinese Journal of Chemical Physics 2008年第4期21卷 301-307页

作者： Kai-jun Yuan Yuan Cheng Feng-yan Wang Xue-ming Yang State Key Laboratory of Molecular Reaction dynamics Dalian Institute of Chemical Physics ChineseAcademy of Sciences Dalian 116023 China

157 nm photodissociation of jet-cooled CH3OH and C2HsOH was studied using the high-n Rydberg atom time-of-flight （TOF） technique. TOF spectra of nascent H atom products were measured. Simulation of these spectra reveals three different atomic H loss processes： one from hydroxyl H elimination, one from methyl （ethyl） H elimination, and one from secondary dissociation of the methoxy （ethoxy） radical. The relative branching ratio indicates secondary dissociation of ethoxy is less important than that of methoxy. The average angular anisotropy parameter of methanol is negative （with β≈-0.3）, indicating the transition dipole moment is perpendicular to the C-O-H plane. The slightly more negative β value of ethanol （with β≈-0.4） implies that ethanol has a longer rotational period. These experimental results indicate that both systems undergo fast internal conversion to the 3s surface after it is excited to the 3px surface, and then dissociate on the 3s surface. The translational energy distribution of the CH3O＋H products reveals extensive CH3 rocking or CH3 umbrella excitation in the CH30 radical. However the vibrational structures are not resolved in the C2H5O radical.

关键词： photodissociation dynamics H atom channel VUV photolysis

photodissociation dynamics of OCS at 207 nm:S(1D2)+CO(X^1Σ^+)Product Channel

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Chinese Journal of Chemical Physics 2020年第3期33卷 291-295,I0002页

作者： Xi-lin Bai Dong-feng Zhao Yang Chen School of Physics and Information Engineering Shanxi Normal UniversityLinfen 041004China Hefei National Laboratory for Physical Sciences at the Microscale Department of Chemical Physicsand Synergetic Innovation Center of Quantum Information&Quantum PhysicsUniversity of Science and Technology of ChinaHefei 230026China

By using the direct current slice velocity map imaging technique,the polarization experiment for S(1D2)product from the ultraviolet photodissociation of carbonyl sulfide at 207 nm was *** angular momentum polarization character of the photofragment S(1D2)was detected via two different resonance enhanced multiphoton ionization intermediate states,1F3 and 1P1,and four different pump-probe laser polarization *** angular distribution of the corresponding CO(X^1Σ^+)coproducts was extracted and analyzed using the molecular-frame polarization and the laboratory-frame anisotropy *** observed total kinetic energy release spectrum indicates that there are three dissociation channels,corresponding to the low,medium,and high kinetic *** sources of the low and medium kinetic energy channels are consistent with those of bimodal translational energy distribution at longer photolysis *** high kinetic energy channel is a new dissociation channel arising from the direct dissociation from the single repulsive A(2^1A′)state.

关键词： photodissociation dynamics Carbonyl sulfide Velocity map imaging

UV photodissociation dynamics of Nitric Acid： The Hydroxyl Elimination Channel

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Chinese Journal of Chemical Physics 2009年第2期22卷 191-196页

作者： Feng-yan Wang Zhi-chao Chen Yong-wei Zhang Quan Shuai Bo Jiang Dong-xu Dai Xiu-yan Wang Xue-ming Yang State Key Laboratory of Molecular Reaction dynamics Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China

Sliced velocity mapping ion imaging technique was employed to investigate the dynamics of the hydroxyl elimination channel in the photodissociaiton of nitric acid in the ultraviolet region. The OH product was detected by （2＋1） resonance enhanced multiphoton ionization via the D^2∑^- electronic state. The total kinetic energy spectra of the OH＋NO2 channel from the photolysis of HONO2 show that both ：NO2（X2A1） and NO2（A2B2） channels are present, suggesting that both 1^1A″ and 2^1A″ excited electronic states of HONO2 are involved in the excitation. The parallel angular distributions suggest that the dissociation of the nitric acid is a fast process in comparison with the rotational period of the HNO3 molecule. The anisotropy parameter β for the hydroxyl elimination channel is found to be dependent on the OH product rotational state as well as the photolysis energy.

关键词： Slice imaging technique photodissociation dynamics Nitric acid OH radical Resonance enhanced multiphoton ionization

Ion-Velocity Map Imaging Study of photodissociation dynamics of Acetaldehyde

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Chinese Journal of Chemical Physics 2014年第3期27卷 249-255页

作者： Zhi-guo Zhang Zhi-chao Chen Cui-mei Zhang Yan-ling Jin Qun Zhang Yang Chen Cun-shun Huang Xue-ming Yang Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics University of Science and Technology of China Hefei 230026 China State Key Laboratory of Molecular Reaction dynamics Dalian Institute of Chemical Physics Dalian 116023 China

The photodissociation dynamics of acetaldehyde in the radical channel CH3＋HCO has been reinvestigated using time-sliced velocity map imaging technique in the photolysis wavelength range of 275-321 nm. The CH3 fragments have been probed via （2＋1） resonance-enhanced multiphoton ionization. Images are measured for CH3 formed in the ground and excited states （v2=0 and 1） of the umbrella vibrational mode. For acetaldehyde dissociation on T1 state after intersystem crossing from S1 state, the products are formed with high translational energy release and low internal excitation. The rotational and vibrational energy of both fragments increases with increasing photodissociation energy. The triplet barrier height is estimated at 3.8814-0.006 eV above the ground state of acetaldehyde.

关键词： Ion-velocity map imaging photodissociation dynamics Acetaldehyde

Ultraviolet photodissociation dynamics of m-Bromofluorobenzene at around 240 nm

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Chinese Journal of Chemical Physics 2018年第4期31卷 563-567,616页

作者： Min Chen Hao Liang Chao He Dong-fengZhao YangChen CAS Center for Excellence for Physical Sciences at the Technology of China Hefei in Quantum Information and Quantum PhysicsHefei National Laboratory Microscaleand Department of Chemical PhysicsUniversity of Science and 230026China

The photodissociation dynamics of m-brornofluorobenzene has been experimentally investi- gated at around 240 nrn using the DC-slice velocity map imaging technique. The kinetic energy release spectra and the recoiling angular distributions of fragmented Br（2P3/2） and Br（2P1/2） atoms from photodissociation of m-bromofluorobenzene have been measured at diff）rent photolysis wavelengths around 240 nm. The experimental results indicate that two dissociation pathways via （pre-）dissociation of the two low-lying 1ππ excited states dominate the production process of the ground state Br（2P3/2） atoms. Because of the weak spin-orbit coupling eff）ct among the low-lying triplet and singlet states, the spin-orbit excited Br（2P1/2） atoms are mainly produced via singlet-triplet state coupling in the dissociation step. The similarity between the present results and that recently reported for o-bromofluorobenzene indicates that the substitution position of the fluorine atom does not significantly affect the UV photodissociation dynamics of bromofluorobenzenes.

关键词： photodissociation dynamics Kinetic energy release spectra Spin-orbit coupling effect

Ultraviolet photodissociation dynamics of DNCO+hν→D+NCO: Two Competitive Pathways

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Chinese Journal of Chemical Physics 2019年第4期32卷 411-416,I0002页

作者： Shu Su Zhen Chen Zhi-chao Chen Guo-rong Wu Dong-xu Dai Kai-jun Yuan Xue-ming Yang State Key Laboratory of Molecular Reaction dynamics Dalian Institute of Chemical Physics Dalian 116023 China University of Chinese Academy of Sciences Beijing 100049 China

photodissociation dynamics of DNCO+hv→D+NCO at photolysis wavelengths between 200 and 235 nm have been studied using the D-atom Rydberg tagging time-of-flight technique. Product translational energy distributions and angular distributions have been determined. Nearly statistical distribution of the product translational energy with nearly isotropic angular distribution was observed at 210-235 nm, which may come from the predissociation pathway of internal conversion from S1 to S0 state followed by decomposition on S0 surface. At shorter photolysis wavelengths, in addition to the statistical distribution, another feature with anisotropic angular distribution appears at high translational energy region, which can be attributed to direct dissociation on S1 surface. Compared with HNCO, the direct dissociation pathway for DNCO photodissociation opens at higher excitation energy. According to our assignment of the NCO internal energy distribution, dominantly bending and a little stretching excited NCO was produced via both dissociation pathways.

关键词： photodissociation dynamics Rydberg tagging time-of-flight spectroscopy Internal conversion

photodissociation dynamics of C2H5Br Between 200 and 210 nm

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Photodissociation Dynamics of C2H5Br Between 200 and 210 nm

A Quantum Wavepacket Study of State-to-State photodissociation dynamics of HOBr/DOBr

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作者：梁昊 Zhengfang Zhou Yang Chen Dongfeng Zhao Hefei National Laboratory for Physical Sciences at the Microscale Department of Chemical PhysicsUniversity of Science and Technology of China

The photodissociation dynamics of the ethyl bromide(C H Br) molecule in the 200-210 nm deep-UV wavelength range has been studied in a collision-free molecular *** Br( P) and Br( P) fragments are ionized via(2+1) resonance-enhanced multiphoton ionization and then probed using time-sliced velocity map imaging to determine their recoiling velocity *** present experimental results suggest that the Brphotofragments are produced as a result of direct dissociation via a repulsive potential energy surface(PES),and the low anisotropy parameter β of Br reveals the existence of a dissociation barrier on the *** reported PESs by high level ab initio calculations have provided a theoretical support in understanding the deep-UV photochemistry of C H Br.

关键词： ethyl bromide(C2H5Br) photodissociation dynamics velocity map imaging deep ultraviolet

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Chinese Journal of Chemical Physics 2020年第2期33卷 173-182,I0002,I0003页

作者： Liang Zhang Bin Jiang Hefei National Laboratory for Physical Science at the Microscale Department of Chemical PhysicsKey Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education InstitutesUniversity of Science and Technology of ChinaHefei 230026China

photodissociation of HOBr is an important step in the reaction network of the depletion of ozone in ***,we report the first three-dimensional potential energy surfaces for the lowest three singlet states for HOBr,based on high level multi reference configuration interaction *** dynamics calculations are performed with a real wavepacket method,yielding not only absorption spectra but also internal state and angular distributions of the photodissociation *** results agree quantitatively with the measured total absorption cross sections of HOBr in the ultraviolet region and reproduce well the observed vibrationally cold and rotationally hot OH/OD fragments via photodissociation of HOBr/DOBr at 266 *** addition,we predict that the recoil anisotropy parameters for OH/OD are close to the limiting value of a parallel transition,suggesting a rapid dissociation process at 266 nm following an in-plane transition from the ground state(1^1A')to the 21A'*** is consistent with the experimental conclusion derived from the measured rotational ***,spin and electronic angular momenta need to be taken into account in the future to achieve a more quantitative agreement with *** work is expected to motivate further experimental investigations for this benchmark system.

关键词： Potential energy surface photodissociation dynamics Wavepacket

Systematical Study on photodissociation dynamics of BrCN from 225 nm to 260 nm

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Chinese Journal of Chemical Physics 2022年第1期35卷 86-94,I0063页

作者： Tonghui Yin Liying Ma Hong Gao Min Cheng Beijing National Laboratory for Molecular Sciences/Institute of Chemistry Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The photodissociation dynamics of Br-C bond cleavage for BrCN in the wavelength region from 225 nm to 260 nm has been studied by our homebuilt time-slice velocity-map imaging *** images for both of the ground state Br(^(2)P_(3/2))and spin-orbit excited Br^(*)(^(2)P_(1/2))channels are obtained at several photodissociation *** the analysis of the translational energy release spectra,the detailed vibrational and rotational distributions of CN products have been measured for both of the Br and Br^(*) *** is found that the internal excitation of the CN products for the Br^(*) channel is colder than that for the Br *** most populated vibrational levels of the CN products are v=0 and 1 for the Br and Br^(*) channels,*** the Br channel,the photodissociation dynamics at longer wavelengths are found to be different from those at shorter wavelengths,as revealed by their dramatically different vibrational and rotational excitations of the CN products.

关键词： photodissociation dynamics Cyanogen bromide Ro-vibronic distribution Energy partitioning Velocity-map imaging