Rotationally resolved photoelectron spectroscopy of hot N_2 formed in the photofragmentation of N_2O

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