New superradiance on the violet line of the mercury ion

Anatoly A. Isaev, Gueorgii G. Petrash

Harold W. Webb, S. C. Wang

Excitation of sodium by excited and by ionized mercury vapor.---The excitation of the sodium spectrum by ionized mercury distilling from an arc was studied in a tube in which conditions were under control. An auxiliary electrode in the stream of mercury vapor was used to increase the number of excited atoms at the point of observation until the excitation due to them predominated over that due to the ions. The spectrum produced by excited mercury atoms was thus compared with that due to mercury ions. The spectrum due to the excited atoms showed the marked "resonance" effect shown earlier by Beutler and Josephy. The spectrum due to mercury ions also showed excitation corresponding to the excitation energy of the metastable mercury atom. This may be accounted for as due to metastable atoms formed as the result of recombination of mercury ions. An alternative explanation is that the excitation of a sodium atom by a mercury ion is by a three body impact involving a mercury ion, a sodium atom and an electron. This was suggested by the fact that when sodium is introduced into the ionized mercury there is a strong enhancement of the mercury lines originating at the two $3S$ levels, which seems to be best explained as due to three body impacts. It seems probable that both this and the above process are of the same nature. It was noted further that the spectrum excited by ionized mercury resembles the chemiluminescence spectrum resulting from mixing sodium and mercuric chloride vapors. The spark line of mercury 3984, not previously found in the luminous mercury stream, was found when sodium was present.

Kyungwon An, James R Harries, Susumu Kuma

John T. Bahns, William C. Stwalley

We report our observations attributable to optical gain through stimulated emission in the violet when sodium vapor is optically pumped with the 350.7-nm line of a krypton ion laser. In addition we present the accompanying fluorescence spectrum which shows previously unreported discrete structure on the short wavelength side of the violet bands.

Chandrasekhara Venkata Raman, Kariamanikkam Srinivasa Krishnan

Abstract In two preliminary papers we have recorded the discovery that when monochromatic light is scattered in a transparent medium (be it gas, vapour, liquid, amorphous solid or crystal), the diffused radiation ceases to be monochromatic, and several new lines or sometimes bands (associated in many cases with a continuous spectrum) appear in the spectrograms of the diffused radiation. Further, the new radiations are, in general, strongly polarised. That the phenomenon is entirely distinct from what is usually known as fluorescence is clear from the fact that the effect is observed when both the exciting radiation and the new radiations generated by it are far removed from the characteristic ultra-violet and infra-red frequencies of the medium. As an illustration we may mention the case of transparent crystalline quartz in which the effect is very well shown with the 4358 A. U. line of mercury as the exciting line, the new lines also appearing in the indigo-blue region of the spectrum. Our preliminary studies have proved conclusively that the effect arises in the following way: The incident quantum of radiation is either scattered as a whole, in which case we have the classical scattering, or else is absorbed in part by the molecules of the medium, the remaining part appearing as a scattered quantum. The part absorbed shifts the molecule to a level of energy different from the initial state. The possibility of a process of this kind, in respect of the electronic state of an atom, was first contemplated by Smekal, and figures prominently in the theory of dispersion due to Kramers and Heisenberg, and in the papers of Schrödinger. Our experiments furnish definite proof of the possibility of such processes, and show that they may occur also in such complicated systems as the molecules of a vapour or a liquid or even in a complete crystal. In the series of papers of which this is the first our further studies of the new radiations will be discussed.