arc spectrum

arc spectrum

[′ärk ‚spek·trəm]
(spectroscopy)
The spectrum of a neutral atom, as opposed to that of a molecule or an ion; it is usually produced by vaporizing the substance in an electric arc; designated by the roman numeral I following the symbol for the element, for example, HeI.
References in periodicals archive ?
On the Absorption Spectrum of Noble Gases at the Arc Spectrum Limit
It is experimentally known that arc spectrum series of noble gases do not converge toward a single limit, but toward two distinct limits.
Superposition of discrete terms of [I.sup.b] spectra upon continuum terms of ordinary arc spectra gives rise to the same situation that occurs in noble gases' spectra between the two limits of the arc spectrum. Nevertheless, the phenomena look different, since, up to the present, in known cases absorption due to the continuum: a) is much less intense than absorption due to discrete terms of [I.sup.b] spectra, and b) decreases very rapidly in intensity with increasing frequency.