Predissociation of the b³Π_g (v = 9) state of He₂ excimer

The predissociation of the v = 9 level in the b³Π_g state by the c³Σ_g⁺ state of helium eximer (He₂) was studied based on the newly observed (9, 3) band in the b³Π_g^-a³Σ _u⁺ system in the region of 12065-12445 cm^-1 employing optical heterodyne-concentration modulation absorption spectroscopy. With the help of the previous potential energy curves and molecular constants of He₂, the corresponding predissociation mechanism for the b ³Π_g (v = 9) state was analyzed. An RKR potential energy curve of b³Π_g and an ab initio potential curve of c³Σ_g⁺ were used to calculate the predissociation linewidths that show basic agreement with observations, which can quantitatively explain the experiments.