Key spectroscopic features of pyrazine lowest-lying 1B1u and 1B2u states
Year: 2025
Type: article
Abstract: We report new spectral assignments from a high-resolution vacuum ultraviolet (VUV) photoabsorption spectrum of pyrazine (C 4 H 4 N 2 ) lowest-lying valence excitations 1 B 1 u 1 ← X ∼ A g 1 and 1 B 2 u 1 ← X ∼ A g 1 in the photon energy range 3.7–6.2 eV (330–200 nm). The electronic state spectroscopy of C 4 H 4 N 2 has been investigated together with quantum chemical calculations at the time-dependant density functional theory (TD-DFT) providing vertical excitation energies and oscillator strengths . The vibronic excitation in the 1 B 1u and 1 B 2u states is accompanied by fine structure assigned to C–H stretching, v 1 ′ a g , C–C stretching, v 2 ′ a g , C–H bending, v 3 ′ a g , ring breathing, v 4 ′ a g , and ring deformation v 5 ′ a g modes. Harmonic frequencies for pyrazine neutral electronic ground- and first excited-states have been obtained at the B3LYP/aug-cc-pVTZ level of theory. Absolute photoabsorption cross-section values are also reported from 3.7 up to 10.8 eV (310–113 nm) and compared with previous data in the literature.
Source: Chemical Physics Letters
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,270
OpenAlex ID: W4409199459