Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell
Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell
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冷缓冲气体池中 YbF 分子的扩散、热化和光泵浦
DOI：
10.1103/physreva.83.023418
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发表时间：
2011
影响因子：
2.9
通讯作者：
Skoff S
中科院分区：
文献类型：
--
作者：
Skoff S
我们在一个充满氦气的低温冷却池中用激光烧蚀的方法制备了密度为100的YbF分子。利用吸收成像和吸收光谱，我们研究的形成，扩散，热化，和光泵的分子。吸收图像显示了远离消融目标的分子的初始快速膨胀，随后是慢得多的扩散到细胞壁。我们研究了扩散的时间常数如何依赖于氦的密度和温度，并获得了在两个不同温度下的YbF-He扩散截面的值。我们测量的平移和旋转温度的分子作为时间的函数，因为形成，获得的特征时间常数的分子热化与细胞壁，并阐明负责限制这种热化率的过程。最后，我们详细研究了探测激光的吸收随强度增加而饱和的情况，表明饱和强度与氦密度成正比。我们用它来估计碰撞率和细胞中分子的密度。
We produce YbF molecules with a density ofmusing laser ablation inside a cryogenically cooled cell filled with a helium buffer gas. Using absorption imaging and absorption spectroscopy we study the formation, diffusion, thermalization, and optical pumping of the molecules. The absorption images show an initial rapid expansion of molecules away from the ablation target followed by a much slower diffusion to the cell walls. We study how the time constant for diffusion depends on the helium density and temperature and obtain values for the YbF-He diffusion cross section at two different temperatures. We measure the translational and rotational temperatures of the molecules as a function of time since formation, obtain the characteristic time constant for the molecules to thermalize with the cell walls, and elucidate the process responsible for limiting this thermalization rate. Finally, we make a detailed study of how the absorption of the probe laser saturates as its intensity increases, showing that the saturation intensity is proportional to the helium density. We use this to estimate collision rates and the density of molecules in the cell.