The Shirlee Jacobs Femtosecond Laser Research Laboratory, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, Israel.
Phys Rev Lett. 2011 Dec 30;107(27):273001. doi: 10.1103/PhysRevLett.107.273001. Epub 2011 Dec 27.
The formation of diatomic molecules with rotational and vibrational coherence is demonstrated experimentally in free-to-bound two-photon femtosecond photoassociation of hot atoms. In a thermal gas at a temperature of 1000 K, pairs of magnesium atoms, colliding in their electronic ground state, are excited into coherent superpositions of bound rovibrational levels in an electronically excited state. The rovibrational coherence is probed by a time-delayed third photon, resulting in quantum beats in the UV fluorescence. A comprehensive theoretical model based on ab initio calculations rationalizes the generation of coherence by Franck-Condon filtering of collision energies and partial waves, quantifying it in terms of an increase in quantum purity of the thermal ensemble. Our results open the way to coherent control of a binary reaction.
实验中证明了具有转动和振动相干性的双原子分子的形成，这是通过自由到束缚的双光子飞秒光缔合来实现的，其中涉及热原子。在温度为 1000 K 的热气体中，碰撞在其电子基态中的镁原子被激发到电子激发态中束缚的转动-振动能级的相干叠加中。通过延迟的第三个光子探测转动-振动相干性，导致在紫外荧光中出现量子拍。基于从头算计算的综合理论模型合理化了相干性的产生，通过碰撞能量和部分波的 Franck-Condon 滤波进行过滤，并根据热系综的量子纯度的提高来量化它。我们的结果为二进制反应的相干控制开辟了道路。
