L3-subshell vacancy state alignment in photon-atom collisions.

Abstract

The differential cross sections for the emission of Ll, L${\mathrm{\ensuremath{\alpha}}}_{2}$, L\ensuremath{\alpha}, L\ensuremath{\beta}, and L\ensuremath{\gamma} groups of L x-ray lines induced in Au by 59.57-keV photons have been measured at different angles varying from 40\ifmmode^\circ\else\textdegree\fi{} to 120\ifmmode^\circ\else\textdegree\fi{} at intervals of 10\ifmmode^\circ\else\textdegree\fi{}. The L${\mathrm{\ensuremath{\alpha}}}_{2}$ line has been isolated by using preferential absorption of the L\ensuremath{\alpha} line in a Zn absorber of suitable thickness. The L x rays represented by the Ll, L${\mathrm{\ensuremath{\alpha}}}_{2}$, and L\ensuremath{\alpha} peaks are found to be anisotropic in the spatial distribution while those in the L\ensuremath{\beta} and L\ensuremath{\gamma} peaks are isotropic. The Ll peak has greater anisotropy than the L\ensuremath{\alpha} peak. The anisotropy of L${\mathrm{\ensuremath{\alpha}}}_{2}$ line is opposite to that of L${\mathrm{\ensuremath{\alpha}}}_{1}$ line. The present results contradict the predictions of Cooper and Zare [Atomic Collision Processes (Gordon and Breach, New York, 1969)], that the vacancy state produced after photoionization is not aligned irrespective of its J value, but confirm those of Flugge, Mehlhorn, and Schmidt [Phys. Rev. Lett. 29, 7 (1972)] that the vacancy state with J>1/2 is aligned.