Rotational-resolved pulsed field ionization-photoelectron study of NO+(A′ 1Σ−,v+=0–17) in the energy range of 17.70–20.10 eV

Abstract

We have obtained partially rotationally resolved pulsed field ionization-photoelectron (PFI-PE) spectra of NO in the energy range of 17.70–20.10 eV, covering ionization transitions of NO+(A′ 1Σ−,v+=0–17,J+)←NO(X 2Π3/2,1/2,v″=0,J″). The PFI-PE bands for NO+(A′ 1Σ−,v+=0–17) obtained here represent the first spectroscopic data that allow the direct determination of rotational constants for these states. As in previous studies, the PFI-PE bands are simulated using the Buckingham–Orr–Sichel model as an empirical scheme to derive reliable spectroscopic constants. The simulation, together with comparison with previous He I photoelectron data, has also provided information on intensity enhancements of PFI-PE bands. Accurate spectroscopic constants for NO+(A′ 1Σ−,v+=0–17) obtained in the present study include ionization energies, vibrational constants (ωe=1272.03±1.45 cm−1, ωeχe=11.924±0.188 cm−1, and ωeye=−0.059±0.007 cm−1), and rotational constants [Be=1.3562±0.0024 cm−1, αe=0.017 80±0.000 61 cm−1, and γe=−(1.574±0.328)×10−4 cm−1]. The simulation indicates that continuum photoelectron states can be formed with orbital angular momenta l up to 5, which corresponds to the maximum total angular momentum transfer of |ΔJ|=13/2. Since the dominant rotational branches observed are ΔJ=±1/2, ±3/2, ±5/2, ±7/2, and +9/2, we conclude that continuum photoelectron states are predominantly produced in l=0–3 in the threshold photoionization of NO(X 2Π3/2,1/2) to form NO+(A′ 1Σ−,v+=0–17).