中文摘要：

利用真空紫外同步辐射光电离（能量范围为8．00—15．50eV）技术结合反射飞行时间质谱仪研究了1，4-二氧六环的光电离和光解离过程．通过超声分子束条件下的光电离质谱测量获得C4H8O2^＋，C3H5^＋C4H7O2^＋，C3H6O^＋，C3H5O^＋，C2H5O^＋，C2H4O^＋，C2H3O^＋,CH3O^＋，C2H6^＋，C2H5^＋／CHO^＋，C2H4^＋以及CH3^＋的离子信号．由光电离效率曲线确定了1，4-二氧六环的电离能及各碎片离子的出现势．通过量化理论计算（G383）获得了与该分子解离过程相关的各反应物，过渡态，中间体及产物的结构和单点能．结合实验测量的离子出现势和理论预测值，获得了1，4-二氧六环的解离通道．研究结果表明分子内部的H转移在1,4-二氧六环的解离光电离过程中起丰导作用．

英文摘要：

The photoionization and photodissociation of 1,4-dioxane have been investigated with a reflectron time-of-flight photoionization mass spectrometry and a tunable vacuum ultraviolet synchrotron radiation in the energy region of 8.0-15.5 eV. Parent ion and fragment ions at m/z 88, 87, 58, 57, 45, 44, 43, 41, 31, 30, 29, 28 and 15 are detected under supersonic conditions. The ionization energy of DX as well as the appearance energies of its fragment ions C4H7O2^＋, C3H6O^＋, C3H5O^＋, C2H5O^＋, C2H4O^＋, C2H3O^＋, C3H5^＋, CH3O^＋, C2H6^＋, C2H5^＋/CHO^＋, C2H4^＋ and CH3^＋ was determined from their photoionization efficiency curves. The optimized structures for the neutrals, cations, transition states and intermediates related to photodissociation of DX are characterized at the B3LYP/6-31＋G（d,p） level and their energies are obtained by G3B3 method. Possible dissociative channels of the DX are proposed based on comparison of experimental AE values and theoretical predicted ones. Intramolecular hydrogen migrations are found to be the dominant processes in most of the fragmentation pathways of 1,4-dioxane.