Infrared Spectroscopic Identification of Mass-Selected Benzonitrile Ions in Neon Matrices: Astrochemical Implications.

Abstract

Benzonitrile (C6H5CN) has emerged as a key astrochemical molecule, yet the vibrational spectra of its ionic forms remain incomplete. In this work, we present the first IR absorption spectra of mass-selected C6H5CN+ and C6H5CN- isolated in solid neon at 3 K. Distinct vibrational features of both ions were identified through their differential response to IR and UV photolysis and comparison with theoretical predictions of vibrational frequencies and intensities. These results provide valuable spectroscopic benchmarks for the identification of benzonitrile ions in space and highlight the effectiveness of matrix-isolation techniques for resolving the vibrational structures of transient molecular ions relevant to astrochemistry.