Phase Changes and Spectral Shifts

The absorption spectrum of benzene has been obtained in the diluents carbon dioxide, ethylene, and ethane over a wide range of densities both above and below the critical temperatures. The red spectral shifts are linear functions of the density throughout the density range for ethylene and ethane and are independent of the state of the diluent. A break in the linear wavelength-density curve occurs at high densities of carbon dioxide. These results support the view that gases and liquids are essentially the same thing in those cases where specific interactions are not involved and suggest further that the radial distribution function remains constant from low to high densities of gas and into the liquid state.