Photodissociation of Molecular Iodine

Electron spin resonance has been used to monitor iodine atom concentrations as functions of iodine pressure, light intensity, and magnetic field strength during in situ irradiation in the banded region and the continuum of I 2 B ( 3 Πo u + ). Evidence for direct predissociation as a major deexcitation process for I 2 ( B ) exists in the parallelism of [I.] vs. [I 2 ] curves in the two regions of photoexcitation. The steady‐state iodine atom concentration varies with the square root of incident light intensity; its dependence on molecular iodine concentration is complex.