Letter | Published:

The Forbidden Lines in the High Frequency Discharge of Mercury, Cadmium, and Zinc

Nature volume 128, page 224 (08 August 1931) | Download Citation



IN addition to the observed results of the intensity modification of spectra in the high frequency discharge in mercury, we have found the forbidden lines 1S 2p1 of mercury and 1S–2p1 and 1S–2p3 of cadmium with moderate intensities. The quartz tube was 15 cm. long and 2 cm. in diameter, and the pressure of vapours was kept at about 0.001 mm. mercury. The spectra were excited with external electrodes by a 10-metre oscillator, and observed in it, end on. Heating the tube caused the discharge to become brighter, and a remarkable intensity modification was observed in mercury, as is seen from the reproduction of the microphotometric records of the spectra at 70° C. and at room temperature (Fig. 1). It can be seen that the effects of a slight rise of temperature are: (1) the vapour emits only the series lines, while spark lines appear at room temperature; (2) the intensities of the series lines decrease quite regularly with the increase of the number of the members; (3) the forbidden line 1S–2p1 enhances more than the neighbouring triplet lines 2p2–12d and 2p2–13d.

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  1. Physical Laboratory, University, Sendai, June 10.

    • J. OKUBO
    •  & E. MATUYAMA


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