0000000000542681
AUTHOR
N. D. Gibson
Depletion of the excited state population in negative ions using laser photodetachment in a gas-filled RF quadrupole ion guide
International audience; 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 collision…
Selective detection of 13C by laser photodetachment mass spectrometry
Abstract In this paper, we demonstrate how laser photodetachment mass spectrometry (LPMS) can be used to selectively detect 13C− ions in the presence of 12C− ions in a low energy ion beam. An isotopically enriched beam of carbon ions consisting of equal amounts of 13C− and 12C− ions was extracted from an ion source. The ions interacted with a laser beam in a collinear geometry over a distance of 70 cm. Residual atoms produced in the photodetachment process were detected in a neutral particle detector placed downstream of the collinear interaction region. By making use of the Doppler effect we were able to selectively photodetach 13C− ions. The number of detected 13C atoms was 13 times large…
Experimental investigation of electron impact onSi2−
A merged beams technique has been used to investigate collisions between electrons and $\text{Si}_{2}{}^{\ensuremath{-}}$ ions over a relative kinetic energy range of 0--210 eV. Absolute cross sections for pure electron detachment, detachment plus dissociation, and dissociation involving atomic and ionic products were measured. The dominant process over the energy range studied is pure electron detachment. A search for a resonance associated with a ${\text{Si}}_{2}$ dianion was made but none was observed.