Abstract
LONDON. Royal Society, May 19.—Lord Rayleigh: Studies of the mercury band spectrum of long duration. The stream of vapour is excited by a current of less than a milliampere, using a hot cathode. It is then observed spectroscopically after leaving the region of discharge. As in previous investigations, the resonance line λ2537 is associatedwith the band spectrum, but the resonance line λ1850 is absent. The important divisions of the band spectrum are: (a) The band at λ2345, with attendant bands of shorter wave-length; (b) the resonance line X2537, with bands within a few Angstroms of it; (c) the fainter maximum at λ2650, and a series of flutings which are made out with difficulty but seem to be associated with it; (d) the broad maximum at λ3300; (e) the broad visual maximum. When the vapour is examined after excitation all these features decay pari passu. The actual time taken to decay to half intensity under the conditions is 1-82 x 10-3 second. If the excited stream of vapour is passed through a tube locally heated to redness, the band (e) is extinguished, (a) and (c) are slightly weakened, but (b) and (d) are almost unaffected. As the vapour passes on to the cold part of the tube the visual light (e) reappears to some extent, and (a) and (c) tend to regain their intensities relative to (b) and (d).
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Societies and Academies. Nature 119, 801–803 (1927). https://doi.org/10.1038/119801a0
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DOI: https://doi.org/10.1038/119801a0