Impact-parameter dependence of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math>-vacancy production in chlorine-argon collisions

Abstract

We have measured the probability per collision for the production of Cl and Ar $K$ vacancies in the bombardment of argon gas targets by 15- and 30-MeV chlorine projectiles. By detecting the Cl and Ar $K$ x rays in coincidence with Cl ions scattered to a known angle we have deduced the dependence of the probability on impact parameter $b$. The sum of Ar and Cl $K$-vacancy production probabilities, presumably a measure of $2p\ensuremath{\sigma}$ vacancy production, is found to depend in magnitude on the charge state of the Cl projectile, but the shape of the summed probability curve, when plotted versus $b$, is not charge-state dependent. The measured shape is close to that expected for $K$-vacancy production via $2p\ensuremath{\sigma}$-$2p\ensuremath{\pi}$ rotational coupling. The data suggest that, for these collisions, the production of $2p\ensuremath{\pi}$ vacancies at large internuclear distances is important and that a two-step mechanism for the production of the $K$ vacancies is operating.