Characteristic x-ray production by argon projectiles moving in graphite targets between 30 and 200 keV

Thick-target yields and x-ray spectra have been measured for argon ions impinging on graphite targets at energies between 30 and 200 keV. The thick-target yields of carbon $K$-shell and argon $L$-shell x rays are analyzed on the basis of a simple model involving multiple collisions and molecular-orbital promotions. The analysis results in average argon $L$-shell fluorescence yields and total decay rates for argon ions traversing the solid. These values are found to be substantially lower than those appropriate to argon ions traversing a gas target. An explanation for the differences is proposed, and found to be corroborated by analysis of the observed x-ray spectra. An approximate determination of the argon $M$-shell vacancy distribution is obtained and compared with beam-foil charge equilibrium measurements.