Rotationally resolved photoelectron spectroscopy of hot N2 formed in the photofragmentation of N2O

The photoionizationdynamics of rotationally hot molecular nitrogen are studied employing resonance enhanced multiphoton ionization in combination with photoelectron spectroscopy.Photodissociation of N_2O at ∼203 nm results in highly rotationally excited N2 fragments in X ^1∑^+_g (N″,v″=0,1) states and O atoms in the excited ^1D_2 state. Photoelectron detection of the rotationally hot N_2 states is performed by a two-photon excitation to the lowest a″ ^1∑^+_g Rydberg state followed by one-photon ionization. The large number of observed rotational levels, from N′=49 up to N′=94, results in improved rotational parameters for a″ ^1∑^+_g (v′=0). In addition, experimental and theoretical rotationally resolved photoelectron spectra of the a″ ^1∑^+_g (v′=0,1;N′) state are presented. In these spectra only ΔN = N^+ − N′ = even transitions are observed, with a dominant ΔN=0 peak and rather weak ΔN = ±2 peaks. The one-photon ionization is dominated by ejection of electrons in p and f partial waves. The agreement between experimental and calculated spectra is excellent.