Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
J Chem Phys. 2012 Sep 14;137(10):104310. doi: 10.1063/1.4748814.
We report on the focusing and guiding of the van der Waals complex formed between benzonitrile molecules (C(6)H(5)CN) and argon atoms in a cold molecular beam using an ac electric quadrupole guide. The distribution of quantum states in the guided beam is non-thermal, because the transmission efficiency depends on the state-dependent effective dipole moment in the applied electric fields. At a specific ac frequency, however, the excitation spectrum can be described by a thermal distribution at a rotational temperature of 0.8 K. From the observed transmission characteristics and a combination of trajectory and Stark-energy calculations we conclude that the permanent electric dipole moment of benzonitrile remains unchanged upon the attachment of the argon atom to within ±5%. By exploiting the different dipole-moment-to-mass ([micro sign]/m) ratios of the complex and the benzonitrile monomer, transmission can be selectively suppressed for or, in the limit of 0 K rotational temperature, restricted to the complex.
我们报告了在冷分子束中使用交流电场四极引导器，对苯甲腈分子（C（6）H（5）CN）和氩原子之间形成的范德华复合物进行聚焦和引导。引导束中的量子态分布是非热的，因为传输效率取决于施加电场中状态相关的有效偶极矩。然而，在特定的交流频率下，激发谱可以用 0.8 K 的旋转温度下的热分布来描述。从观察到的传输特性以及轨迹和 Stark 能量计算的组合，我们得出结论，苯甲腈的永久偶极矩在与氩原子结合时保持不变，误差在±5%以内。通过利用复合物和苯甲腈单体的不同偶极矩与质量比（[micro sign]/m），可以选择性地抑制或在 0 K 旋转温度的极限下限制复合物的传输。
