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VUV and soft x-ray ionization of a plant volatile: Vanillin (C8H8O3)
The Journal of Chemical Physics ( IF 3.1 ) Pub Date : 2016-03-18 12:27:52 , DOI: 10.1063/1.4944084
A. Moreno Betancourt 1 , L. H. Coutinho 2 , R. B. Bernini 3 , C. E. V. de Moura 1 , A. B. Rocha 1 , G. G. B. de Souza 1
Affiliation  

Plant volatiles are emitted by plants in response to several forms of stress, including interaction with energetic photons. In the present work, we discuss the interaction of extreme UV and soft X-rayphotons with a plant volatile, vanillin. The single and double (multiple) ionization of the vanillin molecule have been studied for the first time using time-of-flight mass spectrometry and VUV and soft X-rayphotons (synchrotron radiation, at 12.0 eV, 21.2 eV, 130 eV, 310 eV, 531 eV, and 550 eV). At 12.0 and 21.2 eV, only singly charged species are observed and the parent ion, C8H8O3+, is the dominant species. Energy differences for some selected fragments were calculated theoretically in this energy region. At 130 eV, direct double and triple ionization of the valence electrons may occur. The fragmentation increases and CHO+ becomes one of the main cations in the mass spectrum. The molecular ion is still the dominant species, but other fragments, such as C6H5O+, begin to present similar intensities. At 310 eV, C 1s electrons may be ionized and Auger processes give rise to dissociative doubly ionized cations. Ionization around the O 1s edge has been studied both at the 531 eV resonance and above the ionization edge. Resonant and normal Auger processes play a significant role in each case and a large fragmentation of the molecule is observed at both photonenergies, with intense fragments such as CHO+ and CH3+ being clearly observed. A near edge X-ray absorption fine structurespectrum of the vanillin molecule was obtained around the O 1s ionization threshold. In addition, the fragmentation of vanillin has also been studied using a fast beam of electrons (800 eV), for the sake of comparison.

中文翻译:

植物挥发物的VUV和软X射线电离:香兰素(C8H8O3)

植物对某些形式的压力(包括与高能光子的相互作用)的响应会释放出植物挥发物。在当前的工作中,我们讨论了极端紫外线和软X射线光子与植物挥发性香兰素的相互作用。首次使用飞行时间质谱,VUV和软X射线光子(同步辐射在12.0 eV,21.2 eV,130 eV,310 eV的条件下)研究了香兰素分子的单次和多次电离,531 eV和550 eV)。在12.0和21.2 eV时,仅观察到单电荷物质,母离子C 8 H 8 O 3 +,是优势种。理论上在该能量区域中计算了一些选定片段的能量差。在130 eV时,价电子可能会发生直接的双电离和三电离。碎片增加,CHO +成为质谱中的主要阳离子之一。分子离子仍然是主要物种,但其他片段,例如C 6 H 5 O +,开始呈现出类似的强度。在310 eV,C 1s电子可以被电离,俄歇过程会产生离解性双电离阳离子。在531 eV共振和电离边缘以上都研究了O 1s边缘周围的电离。在每种情况下,共振和正常的俄歇过程都起着重要的作用,并且在两种光子能均观察到分子的大片段化,并且清楚地观察到了强烈的片段,例如CHO +和CH 3 +。在O 1s电离阈值附近获得了香兰素分子的近边缘X射线吸收精细结构光谱。此外,为了进行比较,还使用快速电子束(800 eV)研究了香兰素的碎裂。
更新日期:2016-03-21
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