Depletion of the excited state population in negative ions using laser photodetachment in a gas-filled RF quadrupole ion guide

a O Lindahl (1) , D Hanstorp (1) , O Forstner (2) , N D Gibson (3) , T Gottwald (4) , K Wendt (4) , C C Havener (5) , Y Liu (5)

1 Department of Physics [Gothenburg]
2 Faculty of Physics [Vienna]
3 Department of Physics and Astronomy [Granville, OH]
4 Institut für Physik [Mainz]
5 Physics Division [Oak Ridge]

The depopulation of excited states in beams of negatively charged carbon and silicon ions was demonstrated using collisional detachment and laser photodetachment in a radio frequency quadrupole ion guide filled with helium. The high lying, loosely bound 2 D excited state in C − was completely depleted through collisional detachment alone, which was quantitatively determined within 6%. For Si − the combined signal from the population in the 2 P and 2 D excited states was only partly depleted through collisions in the cooler. The loosely bound 2 P state was likely to be completely depopulated and the more tightly bound 2 D state was partly depopulated through collisions. 98(2)% of the remaining 2 D population was removed by photodetachment in the cooler using less than 2 W laser power. The total reduction of the excited population in Si −, including collisional detachment and photodetachment, was estimated to be 99(1)%. Employing this novel technique to produce a pure ground state negative ion beam offers possibilities to enhance selectivity, as well as accuracy, in high precision experiments on atomic as well as molecular negative ions.

Mots clés: Physical Sciences

a O Lindahl, D Hanstorp, O Forstner, N D Gibson, T Gottwald, et al.. Depletion of the excited state population in negative ions using laser photodetachment in a gas-filled RF quadrupole ion guide. Journal of Physics B: Atomic, Molecular and Optical Physics, 2010, 43 (11), pp.115008. ⟨10.1088/0953-4075/43/11/115008⟩. ⟨hal-00569796⟩