中文摘要：

利用同步辐射真空紫外光电离质谱和理论计算研究了胸腺嘧啶的光解离反应路径，通过改变光子能量得到不同的质谱信号，光子能量在12．0eV时主要的碎片有m／z=98（c4H6N2O＋）、97（c4H5N20＋）、84（c3H4N2O＋或C4H6NO＋）、83（C4H5NO＋）、70（C2NO2＋）和55（C3H5N＋）．并推测了这些碎片可能的光解离生成路径．

英文摘要：

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.