Electronic Spectroscopy of Aniline Ions Embedded in Helium Nanodroplets

Excitation spectra of the (A) over tilde (2)A(2)<-(X) over tilde B-2(1) and (B) over tilde B-2(2)<-(X) over tilde B-2(1) 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 (A) over tilde (2)A(2)<-(X) over tilde B-2(1) 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.