超流氦滴中乙烯和乙烯二聚体的近红外光谱。

Near-infrared spectroscopy of ethylene and ethylene dimer in superfluid helium droplets.

作者信息

Scheele Iris, Conjusteau André, Callegari Carlo, Schmied Roman, Lehmann Kevin K, Scoles Giacinto

机构信息

Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.

出版信息

J Chem Phys. 2005 Mar 8;122(10):104307. doi: 10.1063/1.1854630.

DOI:10.1063/1.1854630

PMID:15836315

Abstract

The nu(5)+nu(9) spectra of ethylene, C(2)H(4), and its dimer, solvated in helium nanodroplets, have been recorded in the wavelength region near 1.6 microm. The monomer transitions show homogeneous broadening of approximately 0.5 cm(-1), which is interpreted as due to an upper state vibrational relaxation lifetime of approximately 10 ps. Nearly resonant vibrational energy transfer (nu(5)+nu(9)-->2nu(5)) is proposed as the relaxation pathway. The dimer gives a single unresolved absorption feature located 4 cm(-1) to the red of the monomer band origin. The scaling of moments of inertia upon solvation in helium is 1.18 for the monomer and >2.5 for the dimer. In terms of the adiabatic following approximation, this classifies the monomer as a fast rotor and the dimer as a slow rotor.

摘要

在波长接近1.6微米的区域记录了乙烯（C₂H₄）及其二聚体在氦纳米液滴中溶剂化后的ν(5)+ν(9)光谱。单体跃迁显示出约0.5厘米⁻¹的均匀展宽，这被解释为由于约10皮秒的上态振动弛豫寿命所致。提出近共振振动能量转移（ν(5)+ν(9)→2ν(5)）作为弛豫途径。二聚体给出一个位于单体谱带原点红色方向4厘米⁻¹处的单一未分辨吸收特征。在氦中溶剂化时，单体的转动惯量缩放因子为1.18，二聚体的则大于2.5。根据绝热跟随近似，这将单体归类为快速转子，二聚体归类为慢速转子。