Pulsed field ionization threshold photelectron spectroscopy of the fluorescing N2O+ (A 2Σ+) state

PFI-ZEKE-photoelectron spectroscopy of N2O using narrow-band VUV laser radiation generated by four-wave mixing in Ar using a KBBF crystal

A new nonlinear optical scheme relying on sum-frequency mixing in a KBe₂BO₃F₂ crystal has been used to generate intense, broadly tunable, narrow-bandwidth, coherent vacuum-ultraviolet (VUV) radiation beyond 16 eV by resonance-enhanced four-wave mixing in Ar. The VUV radiation was used to record high-resolution pulsed-field-ionization zero-kinetic-energy photoelectron spectra of the N₂O⁺ A⁺ ← N₂O X photoionizing transition in the wave-number range from 132 000 cm^-1 to 135 000 cm^-1. The rotational structure of almost all vibrational levels of the A⁺ state with vibrational term values up to 2700 cm^-1 could be resolved, and improved values of the first two adiabatic ionization energies of N₂O, corresponding to the formation of the X^{+ 2}Π_3/2(000) J⁺ = 3/2 and A^{+ 2}Σ⁺(000) N⁺ = 0 levels of N₂O⁺ from the X ¹Σ⁺(000) J″ = 0 ground state [103 969.30(12) cm^-1 and 132 197.70(12) cm^-1, respectively], were derived. The rotational intensity distributions of the bands were found to depend strongly on the value of the vibrational angular momentum of the ionic levels. The vibrational structure is discussed in terms of previously reported effective-Hamiltonian analyses.

A laser-induced fluorescence study of the jet-cooled nitrous oxide cation (N2O+)

Laser-induced fluorescence and wavelength resolved emission spectra of the à (2)Σ(+) - X̃ (2)Π(i) electronic transition of the jet-cooled nitrous oxide cation have been recorded. The ions were produced in a pulsed electric discharge at the exit of a supersonic expansion using a precursor mixture of N(2)O in high pressure argon. Both spin-orbit components of the 0(0) (0) band were studied at high resolution and rotationally analyzed to provide precise molecular constants for the combining states. Emission spectra were obtained by laser excitation of the 0(0) (0), 2(0) (1), 3(0) (1), and 2(0) (2) absorption bands, providing extensive data on the ground state bending, stretching, and combination vibrational levels. These data were fitted to a Renner-Teller model including spin-orbit, anharmonic, and Fermi resonance terms. The observed energy levels and fitted parameters were found to be comparable to those in the literature predicted from an ab initio potential energy surface.