Non-monotonicity of excited state populations observed in a Cu-He hollow cathode discharge

作者：Zheng, XT^*

来源：Chinese Physics Letters, 2005, 22(6): 1474-1477.

An interesting non-monotonic structure in the distribution of excited state populations is observed in a Cu-He hollow cathode discharge, and this is explained by l-changing collisions of the excited states with background gas atoms. At helium pressure of 0.1 Torr and cathode current of 200-300 mA, relative populations of He I 1snp P-1 (n = 2-16) states are measured with the corresponding VUV radiation intensities, and are plotted against excitation energies. As energy levels increase, populations of high-n (n > 10) states are found to decrease much more quickly than low-n (n < 7) populations. For intermediate states (n = 7-10), the declining tendency is interfered by population transfers from 1sns S-1 states due to l-changing collisions, and an obvious non-monotonic structure is formed at relatively low electric current. Measurements have also been carried out for He II np P-2 (n = 2-14) series, in which the l-changing collisions are overwhelmed by Stark quenching of the n(2)S states and thus population interference does not occur.

• 出版日期2005-6
• 单位复旦大学; 上海交通大学