This work reports the first detailed examination of the noncharacteristic x-ray distribution produced during 1-MeV Ar bombardment of silicon. A crystal spectrometer was used to observe the characteristic and noncharacteristic x rays. It is shown that to within 5 eV the noncharacteristic x-ray band is continuous and tails off in the region of 1.4 keV, as required by the molecular x-ray interpretation. We have obtained the true shape of the noncharacteristic x-ray band in the energy range 675-1550 keV by using a rubidium acid phthalate crystal spectrometer calibrated for its relative efficiency. The observation of a broadened argon L line spectrum and multiple satellite line in the Si K spectrum shows that a high degree of excitation is produced in the L shells of both argon and silicon during the collision. © 1975 The American Physical Society.