Rotational-resolved pulsed field ionization photoelectron study of NO+(a 3Σ+,v+=0–16) in the energy range of 15.6–18.2 eV

We have obtained rotationally resolved pulsed field ionization photoelectron (PFI-PE) spectra of NO in the energy range of 15.6–18.2 eV, covering ionization transitions of NO+(a 3Σ+,v+=0–16,J+)←NO(X 2Π3/2,1/2,v″=0,J″). The PFI-PE bands for NO+(a 3Σ+,v+=1–5,7–10,12–14,16) obtained in this experiment represent the first rotationally resolved spectroscopic data for these states. The simulation of these PFI-PE bands provides accurate molecular constants for NO+(a 3Σ+,v+=0–5,7–10,12–14,16), including ionization energies, vibrational constants (ωe+=1295.2±0.1 cm−1, ωe+χe+=15.198±0.002 cm−1), and rotational constants (Be+=1.3501±0.0070 cm−1, αe+=0.0206±0.0001 cm−1). As observed in the PFI-PE study of NO+(X 1Σ+), this experiment reveals a generally increasing trend for the maximum ΔJ value and intensities of higher ΔJ branches as v+ (or bond distance) for NO+(a 3Σ+) is increased. This observation can be taken as strong support of the electron-molecular-ion-core scattering model for angular momentum and energy exchanges in the threshold photoionization of NO.