The radiative and photodissociative properties of the dicarbon molecule, C 2 , in high-lying electronic states are of utmost importance for modeling the photochemical processes that occur in various astronomical environments. Despite extensive spectroscopic studies in the last two centuries, the photodissociation properties of C 2 are still largely unknown, particularly for quantum states in the vacuum ultraviolet (VUV) region. Here, the lifetimes of C 2 for each individual rovibrational level in the recently identified 2 3 Σ g - state are measured for the first time using a VUV-pump-UV-probe photoionization scheme. The lifetimes are found to be strongly dependent on the rotational and vibrational quantum levels in the 2 3 Σ g - state. The strongly rotationally dependent lifetimes observed here indicate that the 2 3 Σ g - state may mainly undergo a predissociation process through couplings with nearby repulsive electronic states. The current observation could have important applications in modeling the interstellar medium and cometary comae.
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