Measurement and calculation of the absolute infrared intensities of PF 3

Abstract

The integrated infrared intensities of the fundamental vibrations of PF 3 are experimentally determined using nitrogen broadening pressures of 550 psi. Since several sets of values arise for the molecular charge distribution parameters ∂ P/∂ S j as a consequence of the inherent sign ambiguity in the measured ∂ P/∂ Q i , a preferred set of derivatives is indicated through comparisons with semiempirical CNDO 2 molecular orbital calculations. Values for the molecular dipole derivatives ∂ P/∂ S j are as follows: A 1 species. ∂P z ∂S 1 = 3.27 ± 0.69 D/ A ̊ and ∂P z ∂S 2 = −3.16 ± 0.28 D/ A ̊ ; E species, ∂P x ∂S 1 = −7.14 ± 0.30 D/ A ̊ and ∂P x ∂S 4 = −0.94 ± 0.01 D/ A ̊ . With the molecular orbital calculations as a guide, the redistribution of the electronic charge during the fundamental vibrations is discussed as a function of net atomic charge density and atomic polarization terms. Charge reorganizations for PF 3 are compared to those for NF 3.