Resonant two-photon two-color photoionization (R2P2CI) spectra of aniline-Arn clusters: Isomer structures and solvent shifts

We present resonant two-photon two-color photoionization (R2P2CI) spectra of a series of aniline-Arn complexes (n=1-6). An apparently anomalous blue shifted spectra for An-Ar3 is explained by a modified spectral shift additivity rule which assigns different shifts to different relative positions of the Ar with respect to aniline. Evidence is presented for the existence of several isomers of clusters with n≥2. It is shown that, by changing the nucleation conditions, it is possible to control the relative populations of the various isomers. (orig.)