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Abstract

Isotoplcally substituted molecules such as HD, unlike ordinary homonuclear diatomic molecules, possess a small electric dipole moment. This effect is a consequence of asymmetric slippage of the electron cloud with nuclear vibration. The matrix element of the dipole moment for the transition v=0 to v=1 in the ground electronic state of HD has been experimentally determined by using Fourier Transform spectroscopic methods. At pressures below 2 atm the width of the lines due to these transitions has been found to be limited by pure Doppler broadening w = 0.026 cm⁻¹, hence no collision narrowing, as occurs in H₂, has been observed. From the resolved lines the absolute intensities were obtained and the matrix element computed. The dipole moment