Change of Frequency of X-Rays Scattered By Bound Electrons

This is a report of the detailed investigation which followed the discovery of "fine structure in scattered x-rays" reported in April, 1928. Molybdenum $K{\alpha }_1$ x-rays were scattered at about 90° by graphite, aluminum and beryllium. Lines from graphite were shifted 0.0013, 0.0023 and 0.0113A to the long wave-length side of Mo $K{\alpha }_1$. From aluminum the shifts were 0.0023, 0.0055 and 0.069A to the long wave side of Mo $K{\alpha }_1$. From beryllium the shifts were 0.0048A to the long wave-length side and 0.00065A to the short wave-length side of Mo $K{\alpha }_1$. Graphite shifts for scattering angles of 42° and 147° were the same as for 90°. This and all curve widths establish the fact that the scattering electrons were ejected with zero kinetic energy. Hence the energy relation is $h{\nu }^1=h\nu \pm \mathrm{Ve}$. From this the critical potentials; 32, 57 and 279 volts are obtained for carbon; 57, 136 and 1550 volts for aluminum; 16 and 119 volts for beryllium.