Production of cold bromine atoms at zero mean velocity by photodissociation.
Production of cold bromine atoms at zero mean velocity by photodissociation.
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DOI：
10.1039/c0cp02472d
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发表时间：
2011-04
期刊：
影响因子：
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通讯作者：
W. G. Doherty;M. T. Bell;T. Softley;A. Rowland;E. Wrede;D. Carty
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文献类型：
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作者：
W. G. Doherty;M. T. Bell;T. Softley;A. Rowland;E. Wrede;D. Carty
本文介绍了利用光解离技术制备溴原子的低温（T < 1 K）样品，其密度估计可达10（8）cm ~（-3）。用（2 + 1）REMPI和速度图离子成像技术研究了Br（2）分子束在Kr中的光解过程，得到了Br + Br* 碎片的速度分布。通过记录图像与不同的延迟时间之间的解离和探测激光，我们调查解离后的时间长度，原子保持在激光焦点，并确定这些原子的速度扩散。通过仔细选择光解能量，发现一小部分原子可以在超过100 μs的延迟时间内被检测到。这些原子的碎片反冲速度矢量与母束速度直接相反，并且在幅度上等于母束速度，从而导致实验室帧速度约为零。在100 μs后，探测原子沿束轴沿着的半高宽速度分布小于5 ms（-1），对应于毫开尔文范围内的温度，打开了这种技术可以用作慢Br原子源的可能性。
The production of a translationally cold (T < 1 K) sample of bromine atoms with estimated densities of up to 10(8) cm(-3) using photodissociation is presented. A molecular beam of Br(2) seeded in Kr is photodissociated into Br + Br* fragments, and the velocity distribution of the atomic fragments is determined using (2 + 1) REMPI and velocity map ion imaging. By recording images with varying delay times between the dissociation and probe lasers, we investigate the length of time after dissociation for which atoms remain in the laser focus, and determine the velocity spread of those atoms. By careful selection of the photolysis energy, it is found that a fraction of the atoms can be detected for delay times in excess of 100 μs. These are atoms for which the fragment recoil velocity vector is directly opposed and equal in magnitude to the parent beam velocity leading to a resultant lab frame velocity of approximately zero. The FWHM velocity spreads of detected atoms along the beam axis after 100 μs are less than 5 ms(-1), corresponding to temperatures in the milliKelvin range, opening the possibility that this technique could be utilized as a slow Br atom source.