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vuv photoionization and Dissociation of Tyramine and Dopamine： the Joint Experimental and Theoretical Studies

Chinese Journal of Chemical Physics 2012年第1期25卷 11-18,I0003页

作者：郭会军叶莉莉贾良元张李东齐飞中国科学技术大学国家同步辐射实验室合肥230029

Photon induced dissociation investigations of neutral tyramine and dopamine are carried out with synchrotron vacuum uRraviolet photoionization mass spectrometry and theoretical calculations. At low photon energy, only molecular ions are measured by virtue of nearthreshold photoionization. While increasing photon energy to 11.7 eV or more, four distinct fragment ions are obtained for tyramine and dopamine, respectively. Besides, the ionization energies of tyramine and dopamine are determined to be 7.984-0.05 and 7.674-0.05 eV by measuring the photoionization efficiency curves of corresponding molecular ions. With help of density function theory calculations, the detailed fragmentation pathways are established as well. These two molecular cations have similar aminoethyl group elimination pathways, CTHsO2＋（m/z=124） and C7H8O＋（m/z=108） are supposed to be generated by the McLafferty rearrangement via γ-hydrogen （7-H） shift inducing β-fission. And CH2NH2＋ is proposed to derive from the direct fission of C7-C8 bond. Besides, the McLafferty rearrangement and the C7-C8 bond fission are validated to be dominant dissociation pathways for tyramine and dopamine cations.

关键词： Tyramine Dopamine vuv photoionization Mass spectrometry Ionization energy Dissociation pathway

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Dissociation Pathway Analysis of Thymine under Low Energy vuv Photon Excitation

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Chinese Journal of Chemical Physics 2011年第3期24卷 275-283,I0003页

作者：李少波郭会军张李东齐飞中国科学技术大学国家同步辐射实验室合肥230029 合肥学院化学与材料工程系合肥230022

Photon-induced dissociation pathways of thymine are investigated with vacuum ultraviolet photoionization mass spectrometry and theoretical calculations. The photoionization mass spectra of thymine at different photon energy are measured and presented. By selecting suitable photon energy, exclusively molecular ion m/z=126 is obtained. At photon energy of 12.0 eV, the major ionic fragments at m/z=98, 97, 84, 83, 70, and 55 are obtained, which are assigned to C4H6N2O＋, C4H5N2O＋, C3H4N2O＋（or C4H6NO＋）, C4H5NO＋, C2NO2＋, and C3H5N＋, respectively. With help of theoretical calculations, the detailed dissociation pathways of thymine at low energy are well established.

关键词： Thymine Dissociation pathway vuv photoionization Mass spectrometry Theoretical calculation

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Experimental studies on ozonation of ethylenethiourea

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Journal of Environmental Sciences 2011年第1期23卷 65-69页

作者： Xinyu Dong Junwang Meng Bo Yang Yang Zhang Jie Gan XiShu Jinian Shu Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China. E-mail: xinyudong@***

The experimental study on ozonation of ethylenethiourea （ETU） is conducted. The reaction of gas-phase ETU with 0.63 × 10^-6 mol/L ozone is carried out in a 200-L reaction chamber. The secondary organic aerosol （SOA） resulted from the ozonation of gas-phase ETU is observed with a scanning mobility particle size （SMPS）. The rapid exponential growth of SOA reveals that the atmospheric lifetime of ETU vapor towards ozone reaction is less than four days. The ozonation of dry ETU particles, ETU-contained water droplets and ETU aqueous solution is investigated with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer （vuv- ATOFMS）. The formation of 2-imidazoline is observed in the ozonation of dry ETU particles and ETU-contained water droplets. The formation of 2-imidazoline and ethvlenerea is observed in the ozonation of ETU aqueous solution.

关键词： ethylenethiourea pesticide ozonation vuv photoionization AMS

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