Electronic Transitions of C₅H₃⁺ and C₅H₃: Neon Matrix and CASPT2 Studies

Abstract

Two electronic transitions at 512.3 and 250 nm of linear-C 5 H + are detected following massselective deposition of m/z = 61 cations into a 6 K neon matrix and assigned to the 1 1 Π ← X 1 Σ + and 1 1 Σ + ← X 1 Σ + systems. Five absorption systems of l-C 5 H with origin bands at 528,7, 482.6, 429.0, 368.5, and 326.8 nm are observed after neutralization of the cations in the matrix and identified as transitions from the X 2 Π to 1 2 ∆, 1 2 Σ − , 1 2 Σ + , 2 2 Π, and 3 2 Π electronic states. The assignment to specific structures is based on calculated excitation energies, vibrational frequencies in the electronic states, along with simulated Franck-Condon profiles. Published by AIP Publishing. [http://dx

Electronic spectra of linear HC5H and cumulene carbene H2C5

“…As demonstrated recently, the H 2 C 5 H + cation is efficiently produced from the methyldiacetylene precursor in the same ion source. 39 B + is easily generated by C-H bond cleavage from H 2 C 5 H + . Moreover, B and B + can also be formed from A and A + via hydrogen migration during the trapping of mass-selected ions.…”