杂环分子-吗啉在同步辐射真空紫外光下的光电离解离研究

本文采用同步辐射真空紫外光电离质谱法和理论计算方法,研究了吗啉单体的光电离、解离及随后的裂解反应.实验测得吗啉单体的垂直电离能为8.37 eV(±0.05),与理论计算值8.41 eV相当吻合.实验观察到荷质比为86、57和29的吗啉碎片离子.实验和理论结果表明:荷质比为86的碎片是通过失去氢原子而产生的,而荷质比为57的碎片是通过开环消除CH_2O而形成的;荷质比为29的碎片是通过消除C_2H_4从碎片离子(C_3H_7N)~+(m/z=57)进一步解离而产生的.这一发现为研究脂肪族化合物的光损伤提供了有价值的见解,可能被转化为活细胞和其他生物系统.

Dissociative Photoionization of Heterocyclic Molecule-Morpholine under VUV Synchrotron Radiation

The radiation damage of biomolecules, in particular with aliphatic compound, has been extensively studied. Morpholine is a typical six-membered aliphatic heterocyclic compound. In the present work, photoionization and dissociation of the morpholine monomer and subsequent fragmentations have been investigated by synchrotron vacuum ultraviolet photoionization mass spectrometry and theoretical calculations. The vertical ionization energy of morpholine monomer is 8.37±0.05 eV, which agrees reasonably well with a theoretical value 8.41 eV of morpholine. Experimentally observed fragmentation of morpholine (m/z=87 amu) gives rise to m/z=86 amu, m/z=57 amu, and m/z=29 amu. Based on experimental and theoretical results, it is found that the m/z=86 amu is produced by losing H atom, the m/z=57 amu is formed by the elimination of CH₂O with a ring-opening process, the m/z=29 amu is generated by further dissociation of the fragment m/z=57 amu (C₃H₇N)⁺ by the elimination of C₂H₄. This finding would provide valuable insight into the photo-damage of aliphatic compounds, which may be related to living cells and other biological system.