Rotationally resolved IR spectroscopy of ammonia trapped in cold helium clusters
Rotationally resolved IR spectroscopy of ammonia trapped in cold helium clusters
复制标题
冷氦簇中捕获的氨的旋转分辨红外光谱
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
F. Rohmund
中科院分区：
文献类型：
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作者：
M. Behrens;U. Buck;R. Fröchtenicht;M. Hartmann;F. Huisken;F. Rohmund
在940 ~ 1060 cm−1的氨伞模式光谱范围内，研究了嵌入在大He团簇中的氨分子的红外分子束损耗光谱。最低旋转能级之间的跃迁可以被解决。通过用自由转子的哈密顿量拟合光谱，我们观察到振动频率向蓝移了17.4 cm−1，旋转常数B有效降低了24%，激发态隧道分裂减少了31%，基态隧道分裂减少了75%。这意味着在宿主星团和氨分子的伞形运动之间存在异常大的相互作用，对旋转有中间影响，而且氦环境对反转也有很大的扰动。
Infrared molecular beam depletion spectroscopy of ammonia molecules embedded in large He clusters has been studied in the spectral region of the ammonia umbrella mode from 940 to 1060 cm−1. The transitions between the lowest rotational energy levels could be resolved. By fitting the spectrum with the Hamiltonian of a free rotor, we observe a large shift of the vibrational frequency of 17.4 cm−1 to the blue, an effective decrease of the rotational constant B by 24%, and a reduction of the tunneling splitting by 31% in the excited and 75% in the ground state. This implies an unusually large interaction between the host cluster and the umbrella motion of the ammonia molecule, an intermediate influence on the rotation and also a large perturbation of the inversion by the helium environment.