Internal conversions and relaxation dynamics in the CN radical in solid neon

In the present work we study the relaxation dynamics of the CN radical in solid Ne following selective excitation of individual vibronic levels of the A²π and B²Σ states. We demonstrate experimentally that when the molecule can relax by either vibrational relaxation or by internal conversions into lower lying levels of a nearby electronic state, the latter process is dominant. Neither near resonance nor perfect Franck-Condon overlaps are required for efficient internal conversions to occur. The rates of these conversions show qualitatively the exponential dependence on the size of the energy gap predicted by theory. The CN radical is stabilized in the solid Ne in several distinct trapping sites; its vibrational constants show negligible perturbation by the solid medium.