The high-frequency spectrum of mercury and the fine structures of 6123 (Hg I) and 4797 (Hg II)

Abstract

It is shown that the previously reported intensity-modifications, found to take place in the high-frequency electrodeless discharge in mercury vapour at low pressures (0.001 mm.), can be completely explained in terms of recently determined electron-impact excitation curves. The modified spectrum arises from the fact that the mean free path is large, enabling the electrons to attain high velocities which result in the strengthening of lines involving upper singlet levels. The high-frequency spectrum at a pressure of 3 mm. is found to be arc-like, supporting the above conclusion. The fine structure of the unclassified line ? 6123 (Hg I) is determined with a Fabry-Perot interferometer and found to have eight components. Four of these form a multiplet and may arise from one isotope only. The line ? 6123 probably involves an upper singlet level. The unclassified spark line ? 4797 (Hg II) shows four fine-structure components, widely separated and of similar intensities.