THE ELECTRONIC SPECTROSCOPY AND STRUCTURE OF COMPLEXES OF ARGON WITH 3-AMINO-S-TETRAZINE IN A SUPERSONIC JET

The structure and spectroscopy of van der Waals clusters between argon and 3-amino-s-tetrazine (AT) has been investigated in a supersonic jet. Low resolution vibrationally resolved fluorescence excitation spectra of AT at a variety of argon gas concentrations enable us to assign the origin transitions for the clusters AT-AR(n), where n = 1 through 6. The frequencies of the van der Waals vibrational modes of these clusters are determined, both in the excited states from the excitation spectra, and in the ground state from single vibronic level emission spectra. High resolution spectroscopy is used to resolve rotational structure in the origin transitions of some of the clusters, and this provides structural information about the clusters. The argon atom in AT-Ar is found to be above the tetrazine ring, and the argon atoms in AT-Ar2 are found to be above and below the tetrazine ring, in all cases having a van der Waals bond length of about 3.3 angstrom. This work is useful in interpreting the results of our previous study on the photodissociation dynamics of van der Waals clusters between argon and AT.