Vibronic spectra of the allyl radical at 6-8 eV with resonance-enhanced multiphoton ionization technique

The ally[ radical was produced in molecular beam by pyrolysis of allyl iodide. The vibronic spectra from ground state to six new electronic states of the allyl radical at 6-8 eV, pi-->3d(xz), pi-->3d(xy), and pi-->ns (n=4, 6, 7, 8) were observed firstly with the aid of time-of-flight mass spectroscopy and resonance-enhanced multiphoton ionization technique. Vibrational progression of v(7) (C-3 bend) with gross spacing of about 430 cm(-1) was observed in ns Rydberg states. The adiabatic ionization potential of the allyl radical was obtained to be (65641 +/- 20) cm(-1) ((8.138 +/- 0.002) eV) by fitting the term values of ns (n=4,6,7,8) Rydberg states with Rydberg formula.