Electronic spectrum of the AlC(2) radical.

E. Chasovskikh (1) , E. B. Jochnowitz (1) , E. Kim (1) , J.P. Maier (1) , Isabelle Navizet (2)

1 Department of Chemistry [Basel]
2 LCT - Laboratoire de Chimie Théorique

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.

Domaines: Chimie théorique et/ou physique

E. Chasovskikh, E. B. Jochnowitz, E. Kim, J.P. Maier, Isabelle Navizet. Electronic spectrum of the AlC(2) radical.. Journal of Physical Chemistry A, 2007, 111 (47), pp.11986-9. ⟨10.1021/jp075169e⟩. ⟨hal-00749393⟩