Pshenichnyuk Stanislav A, Asfandiarov Nail L, Rakhmeyev Rustam G, Komolov Alexei S, Tereshchenko Oleg E
Institute of Molecule and Crystal Physics, Ufa Federal Research Centre, Russian Academy of Sciences, Prospekt Oktyabrya 151, 450075 Ufa, Russia.
St. Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia.
J Chem Phys. 2024 Sep 21;161(11). doi: 10.1063/5.0232036.
Low-energy (0-14 eV) resonance electron interaction and fragment species produced by dissociative electron attachment (DEA) for enantiomeric forms of glutamic acid (Glu) are studied under gas-phase conditions by means of DEA spectroscopy and density functional theory calculations. Contrary to a series of amino acids studied earlier employing the DEA technique, the most abundant species are not associated with the elimination of a hydrogen atom from the parent molecular negative ion. Besides this less intense closed-shell [Glu - H]- fragment, only two mass-selected negative ions, [Glu - 19]- and [Glu - 76]-, are detected within the same electron energy region, with the yield maximum observed at around 0.9 eV. This value matches well the energy of vertical electron attachment into the lowest normally empty π* COOH molecular orbital of Glu located at 0.88 eV according to the present B3LYP/6-31G(d) calculations. Although the detection of asymmetric DEA properties a priori is not accessible under the present experimental conditions, "chirality non-conservation" can be associated with some decay channels. Evidently, the measured spectra for the L- and D-forms are found to be identical, the results, nevertheless, being of interest for the forthcoming experiments utilizing spin-polarized electron beam as a chiral factor in the framework of conventional DEA technique.
在气相条件下，通过解离电子附着（DEA）光谱和密度泛函理论计算，研究了谷氨酸（Glu）对映体形式的低能（0 - 14 eV）共振电子相互作用和由解离电子附着产生的碎片物种。与早期采用DEA技术研究的一系列氨基酸相反，最丰富的物种与从母体分子负离子中消除氢原子无关。除了这种强度较低的闭壳层[Glu - H]-碎片外，在相同的电子能量区域内仅检测到两个质量选择的负离子，即[Glu - 19]-和[Glu - 76]-，其产率最大值出现在约0.9 eV处。根据目前的B3LYP/6 - 31G(d)计算，该值与垂直电子附着到位于0.88 eV的Glu最低正常空π* COOH分子轨道的能量非常匹配。尽管在目前的实验条件下无法先验地检测到不对称DEA性质，但“手性不守恒”可能与某些衰变通道有关。显然，发现L型和D型的测量光谱是相同的，不过，这些结果对于即将进行利用自旋极化电子束作为传统DEA技术框架中的手性因素的实验具有重要意义。
