The Excitation of Spectra by High Frequency Oscillations

Abstract

IN a recent letter to NATURE (Nov. 19, p. 726), Mr. J. R. Clarke gives a brief account of some experiments he has made on the excitation of various spectra in mercury vapour. The wording of his note suggests that he attributes the phenomenon cited to the relative shortness of the wave-length of his oscillating system (300 metres). The apparatus he uses is no other than the ordinary one of electrodeless discharge of which the spectroscopic interest has been clearly shown by Prof. E. Bloch and M. L. Bloch (Journal de Physique, 4, 333; 1923), whose first experiments were made with mercury in the absence of air, which is useless and even derogatory to obtaining pure spectra. This method has often been used since by these authors and others, most frequently, it is true, with damped oscillations, but M. Balasse recently employed undamped waves of about 155-880 metres (Comptes rendus, 1005; 1927) for the excitation of spectra of alkali metals. It may therefore be said that the method described is not merely full of promise, but also that it has already realised all these expectations.