The structure of the carbazole-(Ar)2 trimer from high resolution UV spectroscopy

Highly resolved spectra of the 000 (S1 from S0) transition of the carbazole-Ar2 complex were measured by mass-selective resonance-enhanced two-photon ionization with a narrow-band pulsed laser (delta ny < 140 MHz). The parallel c-type rotational band structure displays regular sharp features which are used to find an accurate set of rotational constants of the trimer. From the experimental result a (2 | 0) structure of the investigated complex with the two Ar atoms located on one side of the carbazole plane can be excluded. Two possible (1 | 1) structures and consequences for the solvation mechanism are discussed.