TY - JOUR
T1 - Reactions of pulsed-laser evaporated uranium atoms with molecular oxygen
T2 - Infrared spectra of UO, UO2, UO3, UO2 +, UO22+ and UO3-O2 in solid argon
AU - Hunt, Rodney D.
AU - Andrews, Lester
PY - 1993
Y1 - 1993
N2 - Uranium atoms from the Nd:YAG laser ablation of a uranium target were codeposited with molecular oxygen and excess argon at 12 K. Infrared spectra following the U+O2 reaction revealed a wide range of reaction products. The 776.0 cm-1 band due to UO2 was the strongest product absorption, strong UO3 bands were observed at 852.5 and 745.5 cm-1, and a weak UO absorption appeared at 819.8 cm -1. These product absorptions are in agreement with earlier work, which evaporated UO2 from a tungsten Knudsen cell at 2000 °C. The 16O2/18O2 reaction gave only U 16O2 and U 18O2, which verified an insertion mechanism. New product absorptions were observed at 952.3, 892.3, and 842.4 cm-1. The 842.4 cm-1 absorption due to the UO 3-O2 complex and the 892.3 cm-1 band assigned to the charge-transfer complex (UO2+) (O2 -) grew markedly at the expense of the other uranium oxides during annealing the matrix to allow diffusion and reaction of O2. With 25% 16O2, 50% 16O18O, and 25% 18O2 samples, the 952.3 cm-1 band became a sharp triplet at 952.3, 936.5, and 904.5 cm-1 and exhibited an isotopic ratio appropriate for a linear OUO species. Agreement of this band with uranyl ion spectra suggests assignment to a (UO22+) complex. Mechanisms of formation of charged species are discussed.
AB - Uranium atoms from the Nd:YAG laser ablation of a uranium target were codeposited with molecular oxygen and excess argon at 12 K. Infrared spectra following the U+O2 reaction revealed a wide range of reaction products. The 776.0 cm-1 band due to UO2 was the strongest product absorption, strong UO3 bands were observed at 852.5 and 745.5 cm-1, and a weak UO absorption appeared at 819.8 cm -1. These product absorptions are in agreement with earlier work, which evaporated UO2 from a tungsten Knudsen cell at 2000 °C. The 16O2/18O2 reaction gave only U 16O2 and U 18O2, which verified an insertion mechanism. New product absorptions were observed at 952.3, 892.3, and 842.4 cm-1. The 842.4 cm-1 absorption due to the UO 3-O2 complex and the 892.3 cm-1 band assigned to the charge-transfer complex (UO2+) (O2 -) grew markedly at the expense of the other uranium oxides during annealing the matrix to allow diffusion and reaction of O2. With 25% 16O2, 50% 16O18O, and 25% 18O2 samples, the 952.3 cm-1 band became a sharp triplet at 952.3, 936.5, and 904.5 cm-1 and exhibited an isotopic ratio appropriate for a linear OUO species. Agreement of this band with uranyl ion spectra suggests assignment to a (UO22+) complex. Mechanisms of formation of charged species are discussed.
UR - http://www.scopus.com/inward/record.url?scp=0027560180&partnerID=8YFLogxK
U2 - 10.1063/1.464045
DO - 10.1063/1.464045
M3 - Article
AN - SCOPUS:0027560180
SN - 0021-9606
VL - 98
SP - 3690
EP - 3696
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 5
ER -