Spectroscopic observation of the four-center reaction CH++O2→CO+(A2Π)+OH

Molecular chemiluminescence was observed when CH+ ions in a beam collided with O2 gas under single collision conditions at 10.7 eVCM. The analysis of the emission properties and an examination of all possible emitters indicate that the source of the chemiluminescence is the CO+(A2Π) ion. This constitutes the first observation of a chemiluminescent four-center reaction (4C-reaction) in an ionic system.