Spectroscopic Study of Hydrogen Bonded7‐Azaindole Clusters

Abstract

The geometric structures of 7‐azaindole (7‐AzI) and its dimer were investigated by laser‐induced fluorescence (LIF). The rotationally resolved LIF spectrum (resolution: ∼0.00003 cm -1 of 7‐AzI monomer shows that (i) rotational constants are A′′ 0.13082(5), B′′ = 0.05677(2), C′′ = 0.03970(1), A′ = 0.12468(5), B′ = 0.056752(2), and C′ = 0.03911(1), and (ii) the transition dipole moment direction is tilted at an angle of ± 21(5) degrees with respect to a axis. The LIF spectrum (resolution: ∼0.06 cm -1 ) of the nonreactive 7‐AzI dimer suggests there are three possibilities for the geometric structure, having “single bonded”, “T‐shaped”, and “non‐planar” structures. The ionization energy of 7‐AzI was determined to be 8.1171(5) eV by using pulsed‐field ionization photoelectron spectroscopy (PFI‐PES). Several vibronic bands of 7‐AzI cation were observed and compared with those of neutral 7‐AzI in the S 0 and S 1 states. The electron binding energies of 7‐AzI cluster anions (2 ≤ n ≤ 5) were determined by photoelectron spectroscopy.