Abstract
Above-treshold ionization (ATI) by femtosecond laser pulses centered at 515,nm is studied for a gas mixture containing the Van-der-Waals complex Ar-H$_2$O. By detecting photoions and -electrons in coincidence, the ATI spectra for Ar, Ar$_2$, H$_2$O, and Ar-H$_2$O are discerned and measured simultaneously. Using an intensity-scanning technique, we observe the red-shift of the ATI spectra as a function of the laser intensity. The intensity-dependent shift of the ATI peak positions observed for Ar-H$_2$O and H$_2$O match but significantly differ from the ones measured for Ar and Ar$_2$. This indicates that the photoelectron is emitted from the H$_2$O site of the complex and the vertical ionization potential of Ar-H$_2$O is determined as $(12.4 \pm 0.1)$,eV. For resacttered electrons, however, an enhancement of high-order ATI is observed for Ar-H$_2$O, as compared to H$_2$O, suggesting that the relatively large Ar atom acts as a scattering center, which influences the ionization dynamics.
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Sebastian Hell
PhD student
I’m curious about atoms and molecules and their dynamics when exposed to ultrashort laser and XUV light pulses as well as ultrafast laser technology.
Matthias Kübel
Junior Research Group Leader
My research interests include attosecond science, atomic and molecular physics and ultrafast laser technology.