NuFuel & MMSNF 2015

First Workshop on Research into Nuclear Fuel in Europe
and Materials Modeling and Simulation for Nuclear Fuels Workshop
Karlsruhe, Germany, November 16th to 18th, 2015

Updated: Tue 08 Dec 2015, 14:27

Talk 3.2: On the Raman Spectrum of Plutonium dioxide: vibrational and crystal electric field modes

Mohamed Naji1, N. Magnani1, S. Mastromarino1,2, J.-Y. Colle1, Dario Manara1,a
  • 1: European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), Hermann-von-Helmholtz Platz 1, PO Box 2340, DE–76125 Karlsruhe, Germany
  • 2: Università di Roma “La Sapienza”, P.le Aldo Moro 5, 00185 Rome, Italy
  • a: Corresponding Author: dario.manara@ec.europa.eu

Abstract

In the present work, the Raman spectrum of plutonium dioxide is studied both experimentally and theoretically. Particular attention has been devoted to the identification of high-energy modes at 2120 cm-1 and 2625 cm-1, the attribution of which has so far been controversial. Crystal Electric Field calculations reported in this work show that these two modes can be respectively assigned to the Γ1 → Γ5 and Γ1 → Γ3 CEF transitions within the 5I4 manifold. These two modes, together with the only vibrational line foreseen by the group theory for the Fm-3m PuO2 symmetry, the T2g Pu-O stretching vibrational peak observed at 478 cm-1, can thus be retained as the Raman fingerprint of fcc plutonium dioxide. In addition to the Stokes spectrum, a parallel study of the T2g anti-Stokes lines, carried out in this research for the very first time, allowed us to reasonably estimate the temperature dependence of the observed Raman modes. The definition of a consistent Raman fingerprint for plutonium dioxide can have important applications in nuclear waste management, nuclear forensic and safeguard activities.