Vibrational Predissociation of S-Tetrazine-Ar van der Waals-Molecules

The visible fluorescence spectroscopy of s-tetrazine in the vapour phase at room temperature is reasonably well understood. Vibrational relaxation data were obtained in the single collision limit for several collision partners [1]. The mode to mode energy flow turned out to be highly selective but not very efficient. With argon as a collision partner for instance the complete removal of one quantum of the 6a mode (703 cm−1) in the electronically excited state was highly improbable, on the other hand with benzene as collision partner at least 20 hard sphere collisions are needed. S-tetrazine photodecomposes with high yield (≥ 99%) after the absorption of visible light, a not yet understood process. Furthermore, the decay time of s-tetrazine in the electronically excited state ranges from ≤ 100 ps up to approximately 2 ns, depending on the vibrational mode excited [2].Van der Waals complexes between s-tetrazine and atomic gases are easily formed in a supersonic beam, which presents a direct method to study photodissociation of the complex [3]. Vibrational predissociation of the Van der Waals complex can be seen as the half collision analog of the vibrational relaxation process.