Institut für Ionenphysik und Angewandte Physik and Center of Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
J Chem Phys. 2010 Jun 7;132(21):214306. doi: 10.1063/1.3429743.
The first detailed study of electron attachment to amino acid clusters is reported. The amino acids chosen for investigation were glycine, alanine, and serine. Clusters of these amino acids were formed inside helium nanodroplets, which provide a convenient low temperature (0.37 K) environment for growing noncovalent clusters. When subjected to low energy (2 eV) electron impact the chemistry for glycine and alanine clusters was found to be similar. In both cases, parent cluster anions were the major products, which contrasts with the corresponding monomers in the gas phase, where the dehydrogenated products (AA(n)-H, where AA = amino acid monomer) dominate. Serine clusters are different, with the major product being the parent anion minus an OH group, an outcome presumably conferred by the facile loss of an OH group from the beta carbon of serine. In addition to the bare parent anions and various fragment anions, helium atoms are also observed attached to both the parent anion clusters and the dehydrogenated parent anion clusters. Finally, we present the first anion yield spectra of amino acid clusters from doped helium nanodroplets as a function of incident electron energy.
首次详细研究了电子对氨基酸团簇的附加作用。选择甘氨酸、丙氨酸和丝氨酸进行研究。这些氨基酸的团簇在氦纳米液滴内形成，氦纳米液滴为非共价团簇的生长提供了便利的低温（0.37 K）环境。当受到低能（2 eV）电子冲击时，发现甘氨酸和丙氨酸团簇的化学性质相似。在这两种情况下，母体簇阴离子都是主要产物，这与气相中相应的单体形成对比，在气相中，脱氢产物(AA(n)-H，其中 AA = 氨基酸单体)占主导地位。丝氨酸团簇则不同，主要产物是母体阴离子减去一个 OH 基团，这一结果可能归因于丝氨酸的β碳上易于失去一个 OH 基团。除了裸露的母体阴离子和各种片段阴离子外，还观察到氦原子与母体阴离子团簇和脱氢的母体阴离子团簇都结合在一起。最后，我们首次呈现了掺杂氦纳米液滴中氨基酸团簇的阴离子产率谱作为入射电子能量的函数。
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