Stimulated emission from the 1Bu-(0) level and the 1Bu+(0)Â +Â 1Bu- (1 and 2) diabatic levels upon excitation to the 1Bu+(0) level in neurosporene and spheroidene

In neurosporene, coherent excitation to the closely-located 1Bu+(0) and 1Bu-(1) levels ('diabatic levels') generated short-lived stimulated emission from the 1Bu-(0) level and long-lived stimulated emission from the diabatic level.