Department of Chemistry and Biochemistry, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA.
J Am Soc Mass Spectrom. 1990 Nov;1(6):419-26. doi: 10.1016/1044-0305(90)85024-G.
Vacuum ultraviolet photoionization by coherent 10.5-eV radiation is evaluated for soft ionization of organic molecules. Coherent 10.5-eV radiation is produced by frequency tripling the third harmonic of an Nd:YAG laser (355 nm) in a mixture of xenon and argon. A number of intermediate size, C6 to C8 , aliphatic compounds are studied to determine the extent and characteristics of fragmentation. Compared with 12-eV electron impact ionization, all show higher molecular ion abundances, less fragmentation, and signiftcant enhancement of low energy rearrangement ions. n-Alkanes, alkenes, ketones, carboxylic acids, and ethers all form predominant molecular ions. Aldehydes and amines show significant molecular ion abundances but also extensive fragmentation. Branched alkanes, dienes, alcohols, and esters show little or no molecular ion, but do have a single dominant fragment ion. Metastable broadening in these spectra gives qualitative information on the energetics of low energy rearrangements. (J Am Soc Mass Spectrom 1990, 1, 419-426).
用相干的 10.5eV 辐射进行真空紫外光电离，以实现有机分子的软电离。相干的 10.5eV 辐射是通过在氙气和氩气的混合物中三次倍频 Nd：YAG 激光（355nm）产生的。研究了许多中等大小的 C6 到 C8 脂肪族化合物，以确定碎片的程度和特征。与 12eV 电子碰撞电离相比，所有化合物的分子离子丰度都更高，碎片较少，低能重排离子显著增强。正构烷烃、烯烃、酮、羧酸和醚都形成主要的分子离子。醛和胺显示出显著的分子离子丰度，但也有广泛的碎片。支链烷烃、二烯烃、醇和酯几乎没有或没有分子离子，但确实有一个单一的主要碎片离子。这些光谱中的亚稳展宽提供了关于低能重排的能量学的定性信息。（美国质谱学会杂志 1990 年，1，419-426）。
