Dissociative ionization of the 1-propanol dimer in a supersonic expansion under tunable synchrotron VUV radiation.
Dissociative ionization of the 1-propanol dimer in a supersonic expansion under tunable synchrotron VUV radiation.
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DOI：
10.1039/c5cp08026f
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发表时间：
2016-05
期刊：
影响因子：
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通讯作者：
Yanmin Tao;Yongjun Hu;W. Xiao;Jiwen Guan;Fu-yi Liu;Xiaobin Shan;Liu-si Sheng
中科院分区：
文献类型：
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作者：
Yanmin Tao;Yongjun Hu;W. Xiao;Jiwen Guan;Fu-yi Liu;Xiaobin Shan;Liu-si Sheng
用同步辐射真空紫外光电离质谱和理论计算研究了正丙醇二聚体的光电离、解离和随后的裂解过程。除了质子化单体阳离子（C3 H7 OH）·H（+）（m/z = 61）和Cα-Cβ键断裂碎片CH 2 O·（C3 H7 OH）H（+）（m/z = 91）外，在入射光子能量为13 eV时测量的质谱表明，一个新的解离通道导致（C3 H7 OH）·H（+）·（C2 H5 OH）（m/z = 107）碎片的形成。用扫描光电离效率谱（PIE）测定了碎片（C3 H7 OH）·H（+）、CH 2 O·（C3 H7 OH）H（+）和（C3 H7 OH）·H（+）·（C2 H5 OH）的出现能量分别为10.05 ± 0.05eV、9.48 ± 0.05eV和12.8 ± 0.1eV。借助理论计算解释了正丙醇离子碎片随真空紫外光子能量的变化。除O-H和Cα-Cβ键断裂外，还出现了一条与Cβ-Cγ键断裂有关的新的解离通道。在该通道中，分子重排（质子转移和越过能垒后的氢转移）产生生成的复合物，然后该复合物解离产生混合的丙醇/乙醇质子结合阳离子（C3 H7 OH）·H（+）·（C2 H5 OH）。这种新的解离通道在以往的乙醇和乙酸二聚体的研究中未见报道。在9-15 eV的光子能量范围内描述了1-丙醇二聚体的光电离和解离过程。
Photoionization and dissociation of the 1-propanol dimer and subsequent fragmentations have been investigated by synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry and theoretical calculations. Besides the protonated monomer cation (C3H7OH)·H(+) (m/z = 61) and Cα-Cβ bond cleavage fragment CH2O·(C3H7OH)H(+) (m/z = 91), the measured mass spectrum at an incident photon energy of 13 eV suggests a new dissociation channel resulting in the formation of the (C3H7OH)·H(+)·(C2H5OH) (m/z = 107) fragment. The appearance energies of the fragments (C3H7OH)·H(+), CH2O·(C3H7OH)H(+) and (C3H7OH)·H(+)·(C2H5OH) are measured at 10.05 ± 0.05 eV, 9.48 ± 0.05 eV, and 12.8 ± 0.1 eV, respectively, by scanning photoionization efficiency (PIE) spectra. The 1-propanol ion fragments as a function of VUV photon energy were interpreted with the aid of theoretical calculations. In addition to O-H and Cα-Cβ bond cleavage, a new dissociation channel related to Cβ-Cγ bond cleavage opens. In this channel, molecular rearrangement (proton transfer and hydrogen transfer after surmounting an energy barrier) gives rise to the generated complex, which then dissociates to produce the mixed propanol/ethanol proton bound cation (C3H7OH)·H(+)·(C2H5OH). This new dissociation channel has not been reported in previous studies of ethanol and acetic acid dimers. The photoionization and dissociation processes of the 1-propanol dimer are described in the photon energy range of 9-15 eV.