A Development of Spectroscopic Technique in the Soft X-Ray Region, with a Typical Spectrum of Barium and its Quantum Mechanical Interpretation

A concave grazing incidence spectrograph £or the long wave x-ray region 40-400 A° if described, together with the technique of operation and some preliminary results of its use. This includes trials of three types of targets, bulk, evaporated and electroplated, as well as a study of the emission characteristics of four types of oxide-coated dull emitter. A solid nickel box, coated by spraying and indirectly heated by a tungsten helix, was found to operate most satisfactorily. A discussion of the difficulties of obtaining vacua better than 10-6 mm. Hg. in a demountable metal x-ray tube is given, together with some devices for obtaining such vacua. Use of an ionization gauge of special design revealed that the emission in the tube was exceedingly sensitive to pressure of residual gases. Schumann plates of lines from carbon, beryllium, strontium and barium were obtained, together with microphotometer curves of their contours, which in the case of barium revealed the characteristic symmetry of a transition between non-conducting atom shells. The theoretical significance of these contours is briefly discussed, together with an outline of the quantum mechanical method involving the use of Brillouin zones and the method of self-consistent fields for calculating energy level distributions for both loosely and tightly bound electrons.