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

• 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 D-2 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 P-2 and D-2 excited states was only partly depleted through collisions in the cooler. The loosely bound P-2 state was likely to be completely depopulated, and the more tightly bound D-2 state was partly depopulated through collisions. 98(2)% of the remaining D-2 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 of enhancing selectivity, as well as accuracy, in high-precision experiments on atomic as well as molecular negative ions.

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NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

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