Soft X-Rays from a Single Nickel Crystal

Abstract

AT the suggestion of Prof. O. W. Richardson, an investigation was made on the excitation of soft X-rays from a single crystal of nickel, kindly lent by Dr. H. H. Potter, of the University of Bristol. The face chosen was the [100] face and the range of potential was from 0 to 300 volts. The experiment was conducted with an all-quartz tube similar to the one used by Richardson and Chalklin (Proc. Roy. Soc., A, 110, p. 247; 1926). Curves were drawn between the applied potential and the energy of the soft X-ray excited as measured by the usual photoelectric method. When the bombarding current was maintained at about 1.5 milliamperes, definite and strong inflections appeared at 63.8, 72.2, 106.2, and 116.0 volts. A very weak inflection was also noted at 94.4 volts. No other inflections were obtained. If, however, the thermionic current was increased to about 3 milliamperes, there appeared also, besides the four strong ones noted above, weak inflections at 129.0, 144.8, 155.9, 179.9, 186.0, and 217.7 volts (all of which appear in the results of Thomas for nickel), while the inflection at 94.4 volts became stronger.