利用真空紫外同步辐射、反射式飞行时间质谱(PI-TOF-MS)和量子化学计算方法研究了气相羟基丙酮(HA)的光电离解离通道。通过测定9.5～15.5 eV光子能量下的 光电离效率(PIE)曲线获得了HA的电离能(IE)(9.78±0.06 eV)以及主要碎片离子(C3H5O+2, C3H5O+, C2H5O+, C2H4O+, CH3CO+, CH2OH+, COH+, C2H3+和CH3+)的出现势(AEs)。使用G3B3//B3LYP/6-311++G(d, p)组合方法进行量化计算, 得到了与该分子解离过程中相关的反应物、过渡态、中间体及产物的最优结构和单点能。 根据实验测得的离子出现势并结合量化计算,分析了羟基丙酮的光电离解离通道及机理。研究结果表明结构重排及分子离子内部氢原子转移在羟基丙酮的光电离解离的 过程中起到非常重要的作用。

The photoionization and dissociative channels of gas-phase hydroxyacetone(HA) are investigated by using vacuum ultraviolet synchrotron radiation, photoionization reflectron time-of-flight mass spectrometer(PI-TOF-MS) and quantum chemistry calculation methods. The ionization energy(IE) of HA,(9.78 ± 0.06) eV, and the appearance energies(AEs) of the major fragment ions C3H5O2+, C3H5O+, C2H5O+, C2H4O+, CH3CO+, CH2OH+, COH+, C2H3+ and CH+3 are obtained by measuring photoionization efficiency(PIE) curves in the photon energy region of 9.5～15.5 eV. Quantitative calculation is carried out by G3B3//B3LYP/6-311++G(d,p) combination method. The reactants, transition states and intermediates related with the molecular dissociation process and the optimal product structure and single point energy are obtained. According to the measured ions appearance potential, the photoionization dissociation channel and mechanism of HA are analyzed combining with quantitative calculation. Results show that the structure rearrangement and molecular ion internal hydrogen atom transfer play an important role in the process of photoionization dissociation of HA.