The predissociation of highly excited states in acetylene by time-resolved photoelectron spectroscopy

Sébastien Zamith (1) , Valérie Blanchet (1) , Bertrand Girard (1) , J. Andersson (2) , S. L. Sorensen (2) , I. Hjelte (3) , O. Björneholm (3) , D. Gauyacq (4) , J. Norin (5) , J. Mauritsson (5) , A. L'Huillier (5)

1 Femto (LCAR)
2 Department of Synchroton Radiation Research
3 Department of Physics
4 PPM - Laboratoire de Photophysique Moléculaire
5 Department of Physics

We study the dynamics of highly excited states in acetylene initiated by an ultrashort vacuum ultraviolet laser pulse. Electronic states lying in the 4s-3d Rydberg region are excited with one femtosecond pulse, and the dynamic development of the states is monitored by a second short pulse which ionizes the system. We show that even for femtosecond pulses where the bandwidth of the exciting pulse covers several electronic states, it is possible to extract short decay lifetimes through time-resolved photoelectron spectroscopy by using a frequency-modulated (chirped) excitation pulse. We report decay lifetimes for the F 4₀² and E 4-5₀² states in acetylene, and for the E 4₀² and E 5₀² states in d-acetylene. The time evolution measured in the electron spectra is compared to decay spectra measured using ion yield and the differences in these results are discussed.

Domaines: Optique [physics.optics]; Chimie-Physique [physics.chem-ph]

Sébastien Zamith, Valérie Blanchet, Bertrand Girard, J. Andersson, S. L. Sorensen, et al.. The predissociation of highly excited states in acetylene by time-resolved photoelectron spectroscopy. Journal of Chemical Physics, 2003, 119, pp.3763. ⟨10.1063/1.1589479⟩. ⟨hal-00005052⟩