The L-1-L2,3M Coster-Kronig spectrum of argon has been measured by using ph
oton excitation. The intensity ratio of 0.30 +/- 0.02 between the L-1-L2,3M
1 main lines and the L-1-L2,3M2,3 lines is extracted from experiment. The e
xperimental results for the ratio and partial decay rates are compared with
present and previous theoretical estimates. [S1050-2947(99)03405-8].