Anomalous nuclear effects on ion charge state distribution in helium gas

The influence of isotope differences on ion charge state yield ratios has never been studied in detail, having been considered negligible. However, we have observed anomalous ion charge state distributions in the thermalization of energetic atomic ions in helium gas; the charge state distributions varied between not only isotopes but also between nuclear states within the same nuclide. The magnitude of the observed results suggests that this anomaly is a universal phenomenon that cannot be explained by the framework of the known isotope effects. Nuclear spin and deformation could be key to unraveling this, but the mechanisms remain an open question.