无机盐可靠性能检测 | 小水合物镁团簇Mg+(H2O)n, n = 1–5的光化学和光谱研究-北京欧兰科技发展有限公司

方案摘要

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应用领域	石油/化工
检测样本	无机盐
检测项目	可靠性能
参考标准	暂无

采用立陶宛Ekspla公司的NT342 B-20-SH-SFG 型可调谐激光，对小水合物镁团簇Mg+(H2O)n, n = 1–5 进行了光解反应研究。

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配置单

Ekspla NT340 高能量可调谐激光器（OPO）
型号：NT340

¥50万 - 100万
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方案详情

Hydrated singly charged magnesium ions Mg+(H2O)n, n 5, in the gas phase are ideal model systems to study photochemical hydrogen evolution since atomic hydrogen is formed over a wide range of wavelengths, with a strong cluster size dependence. Mass selected clusters are stored in the cell of an Fourier transform ion cyclotron resonance mass spectrometer at a temperature of 130 K for several seconds, which allows thermal equilibration via blackbody radiation. Tunable laser light is used for photodissociation. Strong transitions to D1–3 states (correlating with the 3s-3px,y,z transitions of Mg+)
are observed for all cluster sizes, as well as a second absorption band at 4–5 eV for n = 3-5. Due to the lifted degeneracy of the 3px,y,z energy levels of Mg+, the absorptions are broad and red shifted with increasing coordination number of the Mg+ center, from 4.5 eV for n = 1 to 1.8 eV for n = 5.In all cases, H atom formation is the dominant photochemical reaction channel. Quantum chemical calculations using the full range of methods for excited state calculations reproduce the experimental spectra and explain all observed features. In particular, they show that H atom formation occurs in excited states, where the potential energy surface becomes repulsive along the O H coordinate at relatively small distances. The loss of H2O, although thermochemically favorable, is a minor channel because, at least for the clusters n = 1-3, the conical intersection through which the system could relax to the electronic ground state is too high in energy. In some absorption bands, sequential
absorption of multiple photons is required for photodissociation. For n = 1, these multiphoton spectra can be modeled on the basis of quantum chemical calculations.

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