Controversy on the First Ionization Potential of PuO2 (nearly) Settled by New Experimental Evidence

The first ionization potential of the PuO2 molecule was for a long time considered to be 4-5 eV higher than that of UO2. This feature could hardly be explained by the most advanced ?ab-initio? calculations, which, on the other hand, provide satisfactory results for other actinide oxides. From recent experiments, performed with different techniques, a lower ionization potential of approximately 7eV was measured, in better agreement with the theoretical predictions. Our recent experiments, where thermally produced ions were measured, indicate for PuO2 a zero-K ionization energy of 6.24 eV. Considering the still existing uncertainties, one can conclude that these results remove major doubts on the validity of the current theoretical predictions. However, the very small ionization cross section of PuO2 by low-energy electron collisions, which led to the previous spurious assessment of the ion appearance potential, has still an unexplained cause.

CAPONE Franco;  COLLE Jean-Yves;  HIERNAUT Jean-Pol;  RONCHI Claudio; 

2009-07-21

AMER CHEMICAL SOC

JRC30236

1089-5639,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC30236,   

10.1021/jp055452i,