Electron ionisation of cyanoacetylene: ionisation cross sections and dication formation
Electron ionisation of cyanoacetylene: ionisation cross sections and dication formation
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氰乙炔的电子电离：电离截面和双阳离子形成
DOI：
10.1088/1361-6455/ac6781
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Ellis-Gibbings L
中科院分区：
文献类型：
--
作者：
Ellis-Gibbings L
氰基乙炔（HC 3 N）是土卫六大气中重要的痕量组分.我们的报告，第一次，绝对部分电子电离截面和绝对特定的部分电子电离截面的氰基乙炔，以下的实验和计算的调查。我们的方法包括使用2D离子-离子符合质谱产生相对截面，在电子能量范围50-200 eV。这些相对值，然后归一化到一个绝对的规模，使用二进制Bethe（BEB）计算的总电离截面。BEB计算与文献中的先前确定一致。质谱观察HC 2 N+和HCN+，离子的连接性显着不同的中性分子，指向一个丰富的阳离子能量景观拥有几个本地最小值。事实上，[HC 3 N] 2+的极小值涉及各种环状构型揭示了初步的计算调查，沿着与两个极小值与线性和弯曲的几何形状涉及H原子迁移（CCCNH 2+）。这些局部极小值之间的过渡态的能量的测定表明，双阳离子是能够探索在我们的实验能量的这种丰富的构象景观的大部分。这种调查的能量也确定了绝热双电离能为30.3 eV的最低单重态的HCCCN 2+，和30.1 eV的最低三重态。在符合实验中检测到的大部分阳离子对似乎起源于显着的激发二价态，而不是基态。我们观察到HCCCN 2+的5个两体解离，并且在这样的两体过程中产生的离子之一的随后衰变占我们观察到的三体解离的大部分。
Cyanoacetylene (HC 3 N) is an important trace species in the atmosphere of Titan. We report, for the first time, absolute partial electron ionisation cross sections and absolute precursor-specific partial electron ionisation cross sections for cyanoacetylene, following an experimental and computational investigation. Our methodology involves using 2D ion–ion coincidence mass spectrometry to generate relative cross sections, over the electron energy range 50–200 eV. These relative values are then normalised to an absolute scale, using a binary encounter-Bethe (BEB) calculation of the total ionisation cross section. The BEB calculation agrees well with previous determinations in the literature. The mass spectrometric observations of HC 2 N+ and HCN+, ions with a connectivity markedly different to that of the neutral molecule, point towards a rich cationic energy landscape possessing several local minima. Indeed,[HC 3 N] 2+ minima involving a variety of cyclic configurations are revealed by a preliminary computational investigation, along with two minima with linear and bent geometries involving H atom migration (CCCNH 2+). Determination of the energy of a transition state between these local minima indicates that the dication is able to explore the majority of this rich conformational landscape at our experimental energies. This investigation of the energetics also determines an adiabatic double ionisation energy of 30.3 eV for the lowest lying singlet state of HCCCN 2+, and 30.1 eV for the lowest-lying triplet state. The bulk of the cation pairs detected in the coincidence experiment appear to originate from markedly excited dication states, not the ground state. We observe 5 two-body dissociations of HCCCN 2+, and subsequent decay of one of the ions generated in such two-body processes accounts for the majority of three-body dissociations we observe.
DOI：
--
发表时间：
2008
期刊：
影响因子：
--
作者：
S. King
通讯作者：
S. King