Knowledge Bank

Large He clusters (containing up to $104$ atoms) have been employed as a substrate to produce complexes, making use of the pick-up technique. Laser Induced Fluorescence and Beam Depletion are used to spectroscopically investigate such complexes in the frequency region of Na D lines. A strong exponential decay of the total amount of collected fluorescence is observed as a function of $H2$ pressure in the pink-up region. While Beam Depletion Spectra intensities are virtually unaffected, thus demonstrating the high quenching efficiency of $H2$. Spectra are them compared to those of Na atoms on pure He or $H2$ clusters. Interestingly, spectra of $Na-(H2)$ complexes show spectral features similar to those of Na on pure $H2$ clusters only with smaller shifts with respect to the D lines position. Time resolved measurements are currently being taken and will be presented at the meeting.