Understanding the infrared spectrum of bare CH5+

被引:177
作者
Asvany, O
Kumar, P
Redlich, B
Hegemann, I
Schlemmer, S
Marx, D [1 ]
机构
[1] Ruhr Univ Bochum, Lehrstuhl Theoret Chem, D-44780 Bochum, Germany
[2] Leiden Observ, NL-2300 RA Leiden, Netherlands
[3] EURATOM, FOM, Inst Plasma Phys Rijnhuizen, FELIX Facil, NL-3430 BE Nieuwegein, Netherlands
[4] Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany
关键词
D O I
10.1126/science.1113729
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Protonated methane, CH5+, continues to elude definitive structural assignment, as large-amplitude vibrations and hydrogen scrambling challenge both theory,and experiment. Here, the infrared spectrum of bare CH5+ is presented, as detected by reaction with carbon dioxide gas after resonant excitation by the free electron laser at the FELIX facility in the Netherlands. Comparison of the experimental spectrum at similar to 110 kelvin to finite-temperature infrared spectra, calculated by ab initio molecular dynamics, supports fluxionality of bare CH5+ under experimental conditions and provides a dynamical mechanism for exchange of hydrogens between CH3 tripod positions and the three-center bonded H-2 moiety, which eventually leads to full hydrogen scrambling. The possibility of artificially freezing out scrambling and internal rotation in the simulations allowed assignment of the infrared spectrum despite this pronounced fluxionality.
引用
收藏
页码:1219 / 1222
页数:4
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