Article Dans Une Revue Physical Chemistry Chemical Physics Année : 2006

Time-resolved photoion and photoelectron imaging of NO2

Résumé

Time-resolved photoion and photoelectron velocity mapped images from NO2 excited close to its first dissociation limit [to NO(X2) + O(3P2)] have been recorded in a two colour pump–probe experiment, using the frequency-doubled and frequency-tripled output of a regeneratively amplified titanium–sapphire laser. At least three processes are responsible for the observed transient signals; a negative pump–probe signal (corresponding to a 266 nm pump), a very short-lived transient close to the cross-correlation of the pump and probe pulses but on the 400 nm pump side, and a longer-lived positive pump–probe signal that exhibits a signature of wavepacket motion (oscillations). These transients have two main origins; multiphoton excitation of the Rydberg states of NO2 by both 266 and 400 nm light, and electronic relaxation in the 12B2 state of NO2, which leads to a quasi-dissociated NO2 high in the 12A1 electronic ground state and just below the dissociation threshold. The wavepacket motion that we observe is ascribed to states exhibiting free rotation of the O atom about the NO moiety. These states, which are common for loosely bound systems such as a van der Waals complex but unusual for a chemically-bound molecule, have previously been observed in the frequency domain by optical double resonance spectroscopy but never before in the time domain.

Dates et versions

hal-00092077 , version 1 (08-09-2006)

Identifiants

Citer

N.T. Form, B.J. Whitaker, L. Poisson, B. Soep. Time-resolved photoion and photoelectron imaging of NO2. Physical Chemistry Chemical Physics, 2006, 8, pp.2925 - 2932. ⟨10.1039/b602825j⟩. ⟨hal-00092077⟩
116 Consultations
0 Téléchargements

Altmetric

Partager

  • More