Abstract
The efficiency of selective suppression of negative ions by photodetachment in a gas-filled radio
frequency quadrupole ion cooler was investigated with a new detection method. A neodymium
doped yttrium aluminum garnet laser beam at 1064 nm was used to remove Co− ions in the radio
frequency quadrupole cooler and the remaining ions were then probed by photodetachment and
neutral particle detection. More than 99.99% suppression of the Co− ions was observed. Under
identical conditions, only 20% of a Ni− beam was suppressed. The results demonstrate that this
isobar suppression technique can lead to nearly complete elimination of certain isobaric
contaminants in negative ion beams, opening up new experimental possibilities in nuclear and
atomic research and accelerator mass spectrometry.
