Experimental Evidence forXe2Molecules

Abstract

Using the standard absorption-measurement technique, we have measured the attenuation cross sections at Lyman-$\alpha$ (1215.7 Å) for xenon. The attenuation does not follow Beer's law. The observed linear increase in attenuation cross section with rise in gas pressure, and the related decrease in attenuation cross section with increase in temperature, are ascribed to the formation of ${\mathrm{Xe}}_2$ molecules. From consideration of diatomic molecules, methods are presented for deriving the photon scattering cross section for atomic species, the equilibrium constant for the reaction Xe+Xe⇌${\mathrm{Xe}}_2$, the absorption cross section, and the heat of dissociation for ${\mathrm{Xe}}_2$. Their respective values were found to be 5×${10}^{-22\mathrm{}}$ ${\mathrm{cm}}^2$, 2.16×${10}^{-22\mathrm{}}$ ${\mathrm{cm}}^3$/molecule, 1.85×${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$, and 0.03±0.001 eV.