Ethylenedione: An intrinsically short-lived molecule

Ethylenedione C2O2 is one of the elusive small molecules which have remaine d undetected even after numerous attempts with different experimental techn iques, This is surprising, since theoretical studies predicted the triplet state of C2O2 to be stable towards spin-allowed dissociation and hence long -lived. Here we report a comprehensive study of charged and neutral ethylen edione by means of charge reversal and neutralization -reionization mass sp ectrometry. These experimental results, in conjunction with theoretical cal culations, suggest that neutral ethylenedione is intrinsically short-lived rather than being elusive, Both the singlet and triplet states of C2O2 are predicted to dissociate rapidly into two ground-state CO molecules, and for the triplet species, this dissociation involves facile curve-crossing to t he singlet surface within a few nanoseconds.