Asfandiarov NL, Fokin AI, Lukin VG, Nafikova EP, Lomakin GS, Fal'ko VS, Chizhov YV
Institute of Molecular and Crystal Physics, Ufa Research Center, Russian Academy of Sciences, October Prosp. 151, Ufa 450075, Russia.
Rapid Commun Mass Spectrom. 1999 Jun;13(12):1116-1123. doi: 10.1002/(SICI)1097-0231(19990630)13:12<1116::AID-RCM623>3.0.CO;2-M.
A series of anthraquinone (C(14)O(2)H(8)) derivatives has been studied by means of electron capture negative ion mass spectrometry (ECNI-MS), photoelectron spectroscopy (PES), and AM1 quantum chemical calculations. Mean lifetimes of molecular negative ions M(-.) (MNI) have been measured. The mechanism of long-lived MNI formation in the epithermal energy region of incident electrons has been investigated. A simple model of a molecule (a spherical potential well with the repulsive centrifugal term) has been applied for the analysis of the energy dependence of cross sections at the first stage of the electron capture process. It has been shown that a temporary resonance of MNI at the energy approximately 0.5 eV corresponds to a shape resonance with lifetime 1-2.10(-13) s in the f-partial wave (l = 3) of the incident electron. The next resonant state of MNI at the energy approximately 1.7 eV has been associated with the electron excited Feshbach resonance (whose parent state is a triplet npi* transition). In all cases the initial electron state of the MNI relaxes into the ground state by means of a radiationless transition, and the final state of the MNI is a nuclear excited resonance with a lifetime measurable on the mass spectrometry timescale. Copyright 1999 John Wiley & Sons, Ltd.
通过电子捕获负离子质谱法（ECNI-MS）、光电子能谱法（PES）以及AM1量子化学计算，对一系列蒽醌（C(14)O(2)H(8)）衍生物进行了研究。测量了分子负离子M(-.)（MNI）的平均寿命。研究了在入射电子的超热能量区域中长寿命MNI形成的机制。在电子捕获过程的第一阶段，应用了一个简单的分子模型（具有排斥离心项的球形势阱）来分析截面的能量依赖性。结果表明，MNI在能量约为0.5 eV处的临时共振对应于入射电子f分波（l = 3）中寿命为1 - 2×10(-13) s的形状共振。MNI在能量约为1.7 eV处的下一个共振态与电子激发的费什巴赫共振相关（其母态是三重态nπ*跃迁）。在所有情况下，MNI的初始电子态通过无辐射跃迁弛豫到基态，并且MNI的最终态是在质谱时间尺度上可测量寿命的核激发共振。版权所有1999约翰威立父子有限公司。
