Angular dependence of L3-subshell X-ray emission following photoionisation

L-3 -subshell alignment of Th and U ionized by 59.5 keV photons has been investigated by evaluating the angular dependence of L-i (i = l, alpha, eta, beta and gamma) X-ray lines. The angular dependence measurements were performed by measuring the fluorescence cross section, sigma(Li) (i = 1, alpha, eta, beta and gamma) and sigma(Ll) /sigma(L gamma), sigma(L eta)/sigma(L gamma), sigma(L alpha)/sigma(L gamma) and sigma(L beta)/sigma(L gamma) ratios at different angles. It was observed from the measurements that L-i (i = l and alpha) X rays for the L-3 -subshell depended on the emission angle and had an anisotropic spatial distribution. On the other hand, there was no dependence of emission angle and any significant anisotropy for other LX rays. The both Ll and L alpha X-rays originate from the filling of vacancies in states L-3-subshell with J = 3/2. The results of measurements indicate that the L 3 -subshell vacancy states with J = 3/2 are aligned, whereas L-1, and L-2 vacancy states with J = 1/2 are non-aligned. Integral cross-sections for the L-i(i = l, alpha, eta, beta and gamma) X-rays and L subshell fluorescence yields omega(i) (i = 1, 2 and 3) were also determined and results were compared with theoretically calculated values and results of others and fairly good correspondence was observed.