Competing Si 2 CH 4 –H 2 and SiCH 2 –SiH 4 Channels in the Bimolecular Reaction of Ground-State Atomic Carbon (C( 3 P j )) with Disilane (Si 2 H 6 , X 1 A 1g ) under Single Collision Conditions
Competing Si 2 CH 4 –H 2 and SiCH 2 –SiH 4 Channels in the Bimolecular Reaction of Ground-State Atomic Carbon (C( 3 P j )) with Disilane (Si 2 H 6 , X 1 A 1g ) under Single Collision Conditions
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基态碳原子(C( 3 P j ))与乙硅烷(Si 2 H 6 , X 1 A 1g )双分子反应中Si 2 CH 4 →H 2 和SiCH 2 →SiH 4 的竞争通道
DOI：
10.1021/acs.jpca.2c08417
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Kaiser, Ralf I.
中科院分区：
文献类型：
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作者：
Paul, Dababrata;Sun, Bing-Jian;He, Chao;Yang, Zhenghai;Goettl, Shane J.;Yang, Tao;Zhang, Bo-Yu;Chang, Agnes H.;Kaiser, Ralf I.
在交叉分子束机上研究了基态原子碳(C(3PJ))与二硅烷(Si2H6，X1A1g)在单碰撞条件下的双分子气相反应，碰撞能为36.6±4.5kJ·mol-1。实验观察到两个通道：分子氢消除+Si2CH4(反应1)通道和硅烷损失通道，同时生成SiCH2(反应2)，分支比分别为20±3和80±4%。这两个通道都涉及通过长寿命的Si2CH6反应中间体(S)的间接散射动力学；后者在碎裂中间体的旋转平面内的“分子”消除通道中几乎垂直于总角动量矢量喷射分子氢和硅烷。这些分子消除通道与紧密的出射过渡态有关，从轻反应产物氢分子和硅烷中的化学键可以看出，这反映在显着的电子重排上。一旦这些氢化碳化硅星团在碳星(如IRC+10216)的内部包层内形成，恒星风可以将Si2CH4和SiCH2都驱动到包层的外部，在那里它们可以被光解。这对于揭示最近在IrC+10216的星周壳层中观察到的二碳化硅(Si2C)的潜在形成途径特别重要。
The bimolecular gas-phase reaction of ground-state atomic carbon (C(3Pj)) with disilane (Si2H6, X1A1g) was explored under single-collision conditions in a crossed molecular beam machine at a collision energy of 36.6 ± 4.5 kJ mol–1. Two channels were observed: a molecular hydrogen elimination plus Si2CH4(reaction 1) pathway and a silane loss channel along with the formation of SiCH2(reaction 2), with branching ratios of 20 ± 3 and 80 ± 4%, respectively. Both channels involved indirect scattering dynamics via long-lived Si2CH6reaction intermediate(s); the latter eject molecular hydrogen and silane in “molecular” elimination channels within the rotational plane of the fragmenting intermediate nearly perpendicularly to the total angular momentum vector. These molecular elimination channels are associated with tight exit transition states as reflected in a significant electron rearrangement as visible from the chemical bonding in the light reaction products molecular hydrogen and silane. Once these hydrogenated silicon-carbide clusters are formed within the inner envelope of carbon stars such as of IRC + 10216, the stellar wind can drive both Si2CH4and SiCH2to the outside sections of the envelope, where they can be photolyzed. This is of particular importance to unravel potential formation pathways to disilicon monocarbide (Si2C) observed recently in the circumstellar shell of IRC + 10216.