Electronic Spectroscopy of Aniline Ions Embedded in Helium Nanodroplets

Excitation spectra of the Ã2A2←X̃2B1 and B̃2B1←X̃2B1 transitions of aniline cations embedded in helium nanodroplets are reported. The spectra are characterized by broad asymmetric resonances that consist of an intrinsically broadened zero-phonon line, which partially overlaps with the accompanying phonon wing. The band origin of the Ã2A2←X̃2B1 transition reveals a blue-shift of 116 ± 84 cm–1 with respect to the corresponding gas phase transition. This blue-shift is suggested to be related to the presence of a relatively strongly bound high-density helium solvation layer around the ion.