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用Penning型离子阱经碰撞反应H2^++H2→H4^+产生稳定的H4^+,主要的反应产物是H3^+,但十分明显地观测到H4^+信号。H4^+在阱中稳定存在时间长达0.1s量级,远比Kirchner等人测量的10^-6s量级长,最后讨论了生成H4^+的反应过程机制。 相似文献
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应用改进的排列通道量子力学方法(ACQM)对H+2离子与H原子的相互作用进行了研究.研究结果表明,H+2离子与H原子相互作用能够形成稳定的正三角形构型的H+3离子,从而为实验上制备H+3离子找到了一种新的方法. 相似文献
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水分子的化学式其实不是H2 O .根据最新的实验 ,中子和电子与水碰撞的时间为几阿秒 (1 0 - 18s)时探测到的氢和氧的比例约为 1 .5— 1 .所以 ,水的更精确的分子式在这些情况下应该是H1.5O而不是H2 O .按照实验者 (德国柏林技术大学的Chatzidimitriou DreismannA)的说法 ,这个实验“打开了阿秒的时间窗口” ,可能揭示出奇迹般的量子效应 ,以前 ,这种量子效应由于持续的时间太短而没有捕捉到 .这类效应将修正传统的教科书中关于水和其他日常生活中接触到的分子的概念 .此外 ,这些实验能够提供 1 0 0— 5 0 0as时间尺度上的化学反应的新信… 相似文献
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NH++H2→NH2++H反应机理的量子力学研究 总被引:1,自引:1,他引:0
运用耦合簇理论CCSD方法对文献[1]提出的Titan大气中可能生成NH3的链式反应中第三个反应:NH H2→NH2 H进行了热化学计算和分析.发现:①反应(3)在Titan环境中具有良好的反应自发性,在低温下自发反应可能性更大.反应(3)的转变温度为11881.7 K,高于这个温度反应才不可能自发正向进行.运用量子化学MP2方法在6-311g(d)基组下计算研究了反应的机理,发现:②此反应分为两步反应,第一步为放热反应,无能垒.第二步反应的过渡态为平面构型.正反应能垒仅为38.991 Kcal.mol-1,完全可以由第一步反应放出能量来补偿.结果均经过振动分析和IRC计算验证.在不同温度下,尤其是低温下第一步反应平衡常数很大.③由于此反应有较高的反应自发性,可以认为该反应在这六个在Titan大气的低温环境中自然合成NH3的链式反应中起着积极的作用.④耦合簇理论方法和MP2理论两种方法的计算结果是一致的,互相印证了结论的可靠性. 相似文献
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《Molecular physics》2012,110(21-22):2773-2779
A preliminary analysis of the 2CH excitation band in C2H2–N2O in the 1.5 µm range (K. Didriche, C. Lauzin, P. Macko, M. Herman and W.J. Lafferty, Chem. Phys. Letters 469, 35 (2009).), only considering 117 low J-, and Ka - vibration-rotation lines, is significantly extended thanks to the analysis of new spectra including very regular series of lines with J/Ka up to 31/15. 1271 b-type lines were assigned. Perturbations are briefly discussed. The rotational temperature in the experiments is estimated to be 20?K and the upper state mean half-time is 1.6?ns for non perturbed levels. The previous analyses of the 2CH + torsion band in C2H2–N2O and in C2H2–CO2 (C. Lauzin, K. Didriche, T. Földes and M. Herman, Mol. Phys. 109, 2105 (2011).), are also extended to include 286 and 234 lines, respectively, also correcting for calibration errors. New rotational constants are obtained using a rigid rotor Hamiltonian by simultaneously fitting the ground, 2CH and 2CH + torsion states in C2H2–N2O, and the latter state, only, in C2H2–CO2. 相似文献
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The collision-induced dissociation of 10 keV H 2 + ions incident on H2 has been studied in this paper. Total cross sections and angle distributions for the H+-H, H+-H+ and H-H fragmentations are given. Distributions over both angle and velocity have been measured for the H-H+ and H-H fragmentation. 相似文献
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本文用IOS方法和我们改进的Buckingham势计算了H2O-Ar、H2O-CO2混合气体中H2O分子谱线在高温下(600K、900K、1200K、1500K)的压力展宽半宽度。分析了谱线半宽度随温度变化的规律,同时也讨论了半宽度和被加宽分子大小的关系。 相似文献
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用LCAC—SW法计算H+H2(0)→H2+H一维共线反应几率 总被引:1,自引:0,他引:1
用排列通道线性组合散射波方法计算了一维共线反应H+H2(0)→H2+JH的反应几率。在采用较小基组的情况下,得到了与精确量子计算数值相吻合的结果。 相似文献
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本文基于MOLPRO软件包使用从头算方法计算了星际分子H2S及其阳离子H2S+的势能面及光电子能谱.首先,在(U)CCSD/cc-pVQZ理论水平下获取了H2S沿法线坐标展开的势能面,势能面直观描述了不同振动模式耦合对分子能量变化的影响,S-H键的非对称伸缩振动和面内弯曲振动共同作用使得系统势能变化范围明显变大.振动多组态相互作用方法被用来计算非谐振动频率和振动光谱,计算结果显示,倍频和组合频之间出现了强烈的费米共振,使得相应波段处的红外强度显著增强.最后,使用拉曼波函数和收缩不变Krylov子空间方法首次计算了H2SΧ1A1→H2S+ X2B1的光电子能谱.此项研究有助于进一步理解星际分子的内部结构,并为实验研究及星际观测提供参考. 相似文献
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《Surface science》1993,296(3):L33-L37
Most recent experimental work on H2 desorption from the monohydride Si(100) surface seems to point to a pairwise desorption mechanism involving the concerted desorption of two hydrogen atoms on different Si atoms of a single dimer. Using ab initio SCF and CI theory and a cluster model of the surface, the present work finds that the lowest energy pathway is symmetric rather than asymmetric. The desorption energy barrier is calculated to be 3.7 eV. Compared with an experimental value of 2.6 eV, the large barrier suggests that this direct desorption mechanism is not applicable. A multi-step desorption mechanism which involves a delocalized process in the formation of dihydride SiH2 and a localized desorption of H2 is proposed and is shown to explain the experimental observations. 相似文献
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1 INTRODUCTIONMetal ionelectrostaticinterationsarenumerousinchemicalsystemsandhavebeenstudiedextensively[1~ 15] .Specifically ,metal c 相似文献
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《中国物理 B》2019,(4)
Two-dimensional transition metal dichalcogenides(TMDs) provide fertile ground to study the interplay between dimensionality and electronic properties because they exhibit a variety of electronic phases, such as semiconducting, superconducting, charge density waves(CDW) states, and other unconventional physical properties. Compared with other classical TMDs, such as Mott insulator 1T–TaS_2 or superconducting 2H–NbSe_2, bulk 2H–TaSe_2 has been a canonical system and a touchstone for modeling the CDW measurement with a less complex phase diagram. In contrast to ordinary semiconductors that have only single-particle excitations, CDW can have collective excitation and carry current in a collective fashion. However, manipulating this collective condensation of these intriguing systems for device applications has not been explored. Here, the CDW-induced collective driven of non-equilibrium carriers in a field-effect transistor has been demonstrated for the sensitive photodetection at the highly-pursuit terahertz band. We show that the 2H–TaSe_2-based photodetector exhibits a fast photoresponse, as short as 14 μs, and a responsivity of over 27 V/W at room temperature. The fast response time, relative high responsivity and ease of fabrication of these devices yields a new prospect of exploring CDW condensate in TMDs with the aim of overcoming the existing limitations for a variety of practical applications at THz spectral range. 相似文献