Absolute intensities of infrared-active fundamentals and combination bands of gaseous PuF6 and NpF6

Abstract

Results are presented for the absolute integrated molar absorption coefficients of the infrared-active fundamental and binary combination bands of PuF6 and of NpF6 between 1400 and 450 cm−1. The low resolution band contours of the combination bands ν1+ν3, ν2+ν3, ν3+ν5, ν2+ν6, and ν2+ν4 are discussed. From band center positions, the six harmonic wave numbers were obtained and Coriolis constant ζi (i=3, 4, 5, and 6) estimated. For PuF6, the six normal mode vibrations appear to group into one ‘‘local mode’’ stretching at a mean value of 589±50 cm−1 and one local mode bending at 195±5 cm−1. The role of the heavy central atom and the magnitudes of the vibrational force constants are discussed in comparison with UF6. The measured intensity for ν3 is discussed in comparison with previously predicted values.