Abstract
A soft x-ray appearance potential spectrum of SiC has been measured in a region of accelerating potential from 55 to 325 volts. Powder of α-SiC was spread over a copper target and bombarded by electrons emitted from a tungsten filament. Accelerating potential of the electrons was modulated by A. C. voltage of 3 volts at the frequency of 1 kHz. Differential soft x-ray yield was measured as a function of the accelerating potential by means of a BeCu photomultiplier followed by a lock-in amplifier. Resolution of the spectrum is estimated at 8 volts from the applied voltage of the filament as well as the modulation voltage. The observed spectrum shows a low but sharp maximum at 100 volts and a large and broad maximum at 132 volts, and gross structures of the spectrum correspond with those of the silicon L2·3 photoelectric yield spectrum. Therefore, the spectrum is interpreted to be proportional to the differential self convolution of the excitation probability. The maximum at 132 volts is assigned as a structure due to delayed onset of 2p-3d transition.
