Rebecca A. Firth, Kailey M. Bell and Ryan C. Fortenberry*,
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引用次数: 0
摘要
AlO、AlOH和Al(OH)3可在气相中形成,其起始物质只是简单的铝氢化物(AlH和AlH2)和水分子。所有这三种产物都可能是氧化铝团簇的前体,而氧化铝团簇可能会引发星际介质中尘埃颗粒的成核。精确的化学 CCSD(T)-F12b/cc-pVTZ-F12 计算为这些途径提供了放热能量值。例如,AlO 的完全浸没形成放热 51.3 kcal mol-1,这也应导致有利的动力学。为了帮助利用詹姆斯-韦伯太空望远镜(James Webb Space Telescope)和其他天文台的仪器检测反复出现的中间体顺式/反式-HAlOH,本研究利用高精度的四元力场方法报告了旋转和振动光谱数据。顺式异构体和反式异构体在 1807.9 cm-1 处的ν2 伸缩频率显示出 185 km mol-1 的谐波强度,在 534.2 cm-1 处的反不对称弯曲 (ν4)显示出 213 km mol-1 的谐波强度。这大约是水的反不对称伸展强度的三倍。顺式异构体的偶极矩较小,为 0.83 D,而反式异构体的偶极矩适中,为 1.49 D。
Formation of AlO, AlOH, and Al(OH)3 in the Interstellar Medium and Circumstellar Envelopes of AGB Stars
AlO, AlOH, and Al(OH)3 can be formed in the gas-phase starting from nothing more than simple aluminum hydrides (AlH and AlH2) and water molecules. All three products are probable precursors to aluminum oxide clusters that may initiate the nucleation of dust grains in the interstellar medium. Chemically accurate CCSD(T)-F12b/cc-pVTZ-F12 computations provide exothermic energetic values for these pathways. For example, the fully submerged formation of AlO is exothermic by 51.3 kcal mol–1, and this should also lead to favorable kinetics. To aid in the detection of the recurring intermediate cis/trans-HAlOH with instrumentation located on the James Webb Space Telescope, among other observatories, rotational and vibrational spectroscopic data are reported by utilizing a highly accurate quartic force field methodology. The ν2 stretching frequency at 1807.9 cm–1 exhibits an anharmonic intensity of 185 km mol–1 and the antisymmetric bend (ν4) at 534.2 cm–1 exhibits an anharmonic intensity of 213 km mol–1 for the cis and trans isomers, respectively. These are roughly three times the antisymmetric stretch intensity of water. The cis isomer has a smaller dipole moment of 0.83 D, while the trans isomer contains a moderate dipole moment of 1.49 D. These properties indicate that both of these isomers can be observed through vibrational and rotational spectroscopic techniques.
期刊介绍:
The scope of ACS Earth and Space Chemistry includes the application of analytical, experimental and theoretical chemistry to investigate research questions relevant to the Earth and Space. The journal encompasses the highly interdisciplinary nature of research in this area, while emphasizing chemistry and chemical research tools as the unifying theme. The journal publishes broadly in the domains of high- and low-temperature geochemistry, atmospheric chemistry, marine chemistry, planetary chemistry, astrochemistry, and analytical geochemistry. ACS Earth and Space Chemistry publishes Articles, Letters, Reviews, and Features to provide flexible formats to readily communicate all aspects of research in these fields.