Valence shell threshold photoelectron spectroscopy of C3Hx (x = 0–3)

Abstract

We present the photoelectron spectra of C₃H_x (x = 0–3) formed in a microwave discharge flow-tube reactor by consecutive H abstractions from C₃H₄ (C₃H_x + F → C₃H_x−1 + HF (x = 1–4)), but also from F + CH₄ schemes by secondary reactions. The spectra were obtained combining tunable VUV synchrotron radiation with double imaging electron/ion coincidence techniques, yielding mass-selected threshold photoelectron spectra. The obtained results complement not only existing ones, but for the first time the photoelectron spectra of C₃, cyclic and linear C₃H (c,l-C₃H) as well as of the excited states of C₃H₃ are reported. In the case of c-C₃H, l,t-C₃H₂ and C₃H₃, Franck–Condon simulations have been performed in order to assign the vibrational structure. The adiabatic ionization energies of these radicals are reported and compared to ab initio calculated values as well as to theoretical values using known enthalpies of formation.