Jun-Ying Feng

1. Introduction Click to copy section linkSection link copied! Hydrogenated polycyclic aromatic hydrocarbons (HPAHs) are polycyclic aromatic hydrocarbons (PAHs) that incorporate additional hydrogen atoms into their carbon skeletons, partially saturating the aromatic rings and introducing aliphatic C–H bonds. (1) In astrochemistry, these species serve as a bridge between the chemical and spectral properties of aromatic and aliphatic carbonaceous materials in space.

4.1. Assignments of Features in Group B to 4-HC14H10 and Group C to 3-HC14H10 Spectral features in groups B and C in the region 700–865 cm –1 are displayed in Figure 5 and compared with predicted spectra of five low-lying isomers of HC 14 H 10 . These stick spectra are derived from scaled harmonic vibrational wavenumbers and IR intensities predicted by the B3LYP/6-311++G(d,p) method. The spectrum measured after maintaining the matrix in darkness is shown in Figure 5 c.

The IR spectra of benzoic acid (BA), (BA)(H2O)n and (BA)2(H2O)n (n = 1, 2) clusters, and their ring-deuterated isotopologues in the 2800–3750 cm–1 region were measured with IR-vacuum ultraviolet spectroscopy under the jet-cooled condition. For (BA)(H2O) and (BA)(H2O)2, only a single isomer was observed for each species, whereas for (BA)2(H2O) and (BA)2(H2O)2, more than one isomers were present.