Band-to-band transitions and critical points in the near-infrared to vacuum ultraviolet dielectric functions of single crystal urania and thoria

Abstract

Hot electron mediated enhancement in the decay rates of persistent photocurrent in gold nanoparticles embedded indium oxide films

Interband Transitions And Critical Points Of Single Crystal Thoria Compared To Urania

“…These improved single crystals make higher quality assessments of the UO2 and ThO2 optical and semiconductor properties possible, as defect contributions to the complex dielectric function are much suppressed [13]. In this study, we validate the observed interband transitions identified in variable angle ellipsometry [12,13] with cathode luminescence and theory.…”

“…Single crystals of UO2 were grown by hydrothermal synthesis [12,13,[16][17][18][19][20][21][22], as described in [12,13,22]. Further hydrothermal growth information is detailed in [16].…”

“…Experimentally, Schoenes studied the incident light reflectivity off UO2 single crystals in the photon energy range of 0.03-13 eV, from which the complex dielectric function e(w) = e1(w) + ie2(w) has been derived [10]. This effort to extract the complex dielectric function has been repeated more recently by Siekhaus and J. Crowhurst [11] as well as Mock, Dugan and coworkers [12,13]. These have transitional charactertistics that are shifted significantly compared to reflectivity measurements by Schoenes [10].…”

“…Absorption of UO2 thin films, by optical transmission has also been measured [14], while the optical properties for both ThO2 and UO2 have been previously calculated [15] using the Heyd-Scuseria-Ernzerhof (HSE) functional. The challenges of growing uranium oxide singlecrystals have been addressed with the fabrication of high-quality, single crystal actinide oxide samples using a hydrothermal synthesis growth technique [12,13,[16][17][18][19][20][21][22]. This growth process has produced bulk single crystals of near-stoichiometric UO2 [12,13,17,[20][21][22] and ThO2 [13,18,19,22].…”

“…The challenges of growing uranium oxide singlecrystals have been addressed with the fabrication of high-quality, single crystal actinide oxide samples using a hydrothermal synthesis growth technique [12,13,[16][17][18][19][20][21][22]. This growth process has produced bulk single crystals of near-stoichiometric UO2 [12,13,17,[20][21][22] and ThO2 [13,18,19,22]. These improved single crystals make higher quality assessments of the UO2 and ThO2 optical and semiconductor properties possible, as defect contributions to the complex dielectric function are much suppressed [13].…”