Isobar Suppression by Photodetachment in a Gas-Filled RF Quadrupole Ion Guide

A novel technique based on selective non-resonant laser photodetachment in a radio frequency quadrupole ion guide is demonstrated for efficient suppression of isobaric contaminants in negative ion beams. The use of the quadrupole ion guide substantially increases the interaction time of the ions with the laser, significantly increasing the efficiency of the photodetachment process. In a proof–of-principle experiment, we achieved 95% suppression of⁵⁹Co^-ions by photodetachment while under identical conditions only 10% of⁵⁸Ni^-ions were neutralized.