Valence shell absolute photoabsorption oscillator strengths, constrained dipole oscillator strength distributions, and dipole properties for CH3NH2, (CH3)2NH, and (CH3)3N

Abstract

Dipole (e,e) spectroscopy has been used to measure the absolute photoabsorption oscillator strengths (cross sections) for the valence shells of CH3NH2, (CH3)2NH, and (CH3)3N from the photoabsorption threshold to 250 eV at low resolution (∼1 eV fwhm) and to 31 eV at high resolution (0.048 eV fwhm). The observed peaks in the photoabsorption spectra of the methylamines have been assigned to transitions to Rydberg orbital upper states. Our measured photoabsorption data, augmented by mixture rule estimates for high photon energies, have been used in conjunction with Thomas–Reiche–Kuhn sum rule and molar refractivity constraints, to construct constrained dipole oscillator strength distributions for each of the methylamines. From these constrained dipole oscillator strength distributions a wide range of related dipole properties have been calculated for each of the methylamines, and in most cases the results so obtained represent the first (reliable) determination of these properties.