Electronic spectrum of the AlC(2) radical

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 111; no. 47; pp. 11986 - 11989
• Main Authors: Chasovskikh, Egor, Jochnowitz, Evan B, Kim, Eunsook, Maier, John P, Navizet, Isabelle
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 29.11.2007
• Subjects: Chemical Sciences; or physical chemistry; Theoretical and
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp075169e

An electronic transition of the AlC2 radical (C2v structure) has been observed using laser-induced fluorescence spectroscopy. The molecule was prepared in a supersonic expansion by ablation of an aluminum rod in the presence of acetylene gas. A spectrum was recorded in the 451-453 nm region and assigned to the C 2B2-X 2A1 system (T0 = 22,102.7 cm(-1)) based on a rotational analysis and agreement with calculated molecular parameters and excitation energies. Ab initio results obtained using couple cluster methods are in accord with previous theoretical work which concludes that ground-state AlC2 possesses a T-shaped C2v 2A1 geometry, with the linear 2Sigma+ AlCC isomer 0.70 eV higher in energy. A fit of the experimental spectrum yields rotational constants in the ground and electronically excited states that are in reasonable agreement with the calculated values: A'' = 1.7093(107), B'' = 0.4052(50), C'' = 0.3228(49) cm(-1) for the X 2A1 state, and A' = 1.5621(137), B' = 0.4028(46), C' = 0.3201(54) cm(-1) for C 2B2. Variation in individual fluorescence lifetimes suggests that the emitting C 2B2 state undergoes rovibronic mixing with lower lying electronic states.