The photoionization of neutral aluminium

The R-matrix method is used to calculate the photoionization cross section of ground state aluminium atoms Al( 2 P 0 ), leaving the residual ions in their ground Al + ( 1 S e ) or first two excited states Al + ( 3 P 0 , 1 P 0 ). The initial bound state Al( 2 P 0 ) as well as the three possible final continuum states (Al + +e - )( 2 S e , 2 P e , 2 D e ) are represented consistently by R-matrix expansions in terms of three lowest states of the ion Al + ( 1 S e , 3 P 0 , 1 P 0 ). These ionic states are in turn described by accurate configuration-interaction wavefunctions. Good agreement is obtained with recent experiments by Kohl and Parkinson (1975) and by Esteva (1974) and results probably accurate to better than 15% are given from 2070 AA to 570 AA.