J.J.M. Beenakker

A survey of experimental data related to the non-spherical interaction for simple classical linear molecules and their mixtures with noble gases

The available experimental data related to the non-spherical interaction for simple “classical” linear molecules (with the emphasis on N2 and CO) and their mixtures with noble gases is critically surveyed. The compilation includes data on sound absorption, magnetic field effects on transport properties, flow birefringence, depolarized Rayleigh and Raman light scattering, nuclear magnetic relaxation and pure rotational dipolar absorption. The results are all presented in terms of effective collision cross sections in order to facilitate a comparison with future calculations based on the intermolecular potential.

Temperature dependence of depolarized Rayleigh light scattering in N2-noble gas systems

Abstract Depolarized Rayleigh light scattering spectra have been measured for pure N2 and for mixtures of N2 with He, Ne or Ar as a function of concentration in the temperature range 120–295 K. The pressure-broadening coefficients and the corresponding cross sections for N2-noble gas collisions have been determined. The data have been used to check the applicability of various theoretical N2-noble gas interaction potentials.

A comparison of data on the viscomagnetic effect, flow birefringence and depolarized Rayleigh line broadening

A comparison of data on the viscomagnetic effect, flow birefringence and depolarized Rayleigh line broadening for various gases of linear molecules at temperatures between 90 and 293 K is carried out. From the combined results information is obtained on the scalar structure of the non-equilibrium angular momentum polarization produced in viscous flow.

Flow birefringence in gases at room temperature: New absolute values

Absolute flow birefringence data are required for a final consistency test of the kinetic theory of angular momentum polarizations. In order to obtain reliable values the possible sources of error in the experimental set-up used to measure flow birefringence in gases have been investigated. Special attention has been given to the calibration procedure and to the flow characteristics of the cylindrical Couette flow cell. New absolute data for various simple gases at 293 K are presented. The results will be used in a subsequent paper to get information on the scalar factor of the angular momentum polarization in viscous flow.

The role of the internal energy in the distribution function of a heat conducting gas

Using a state-selective optical technique, we have measured directly the nonequilibrium distribution function f in heat conducting iodine gas as a function of the rotational and vibrational quantum numbers. The results show that, contrary to the case for translational energy, no rapid convergence exists for the expansion of f in polynomials (Wang-Chang-Uhlenbeck polynomials) containing the rotational or vibrational energy. The weight of the polynomials quadratic in the internal energy relative to polynomials of the first degree in the internal energy is found to be about 9% for the rotational energy and about 27% for the vibrational energy.

Flow birefringence in gases: The temperature dependence

A method is described for measurements of the temperature dependence of flow birefringence in gases between 90 and 293 K. Results are presented for CO, N2, HD and oD2.

The temperature dependence of flow birefringence in gases and the scalar factor of angular momentum polarization in viscous flow

Abstract Flow birefringence measurements have been performed for several linear molecules between 90 and 293 K. From a comparison with viscomagnetic effect data, information is obtained about the scalar factor of the angular momentum polarization present in viscous flow, of which only the tensorial factor had been determined. Experiments on hydrogen isotopes, for which only one rotational level is excited, confirm the assumption that the polarization does not depend on the translational energy.

Optical determination of the J-dependence of angular momentum alignment in a heat conducting gas

We have directly observed the flow of angular momentum alignment in a heat conducting gas of rotating molecules (Kagan polarization). This alignment is measured as a function of the angular momentum, J, from the polarization of the laser-induced fluorescence of iodine gas. A difficulty to overcome is that the gas as a whole does not show alignment, so that the detection method must be able to distinguish between molecular fluxes parallel and antiparallel to the temperature gradient. This is achieved by making use of the relatively long lifetime of the excited I2 molecule. The long standing question of the precise form of the angular momentum alignment with respect to the magnitude of J is now unambiguously answered for classical rotors: the Kagan polarization is proportional to J2. Also the sign of the alignment has been determined.

Experiments on the influence of stereospecific interaction on the liquid density of some stereoisomers

The liquid density difference between optically pure stereoisomers and their racemic mixture, resulting from stereospecific interactions, is determined in a differential experiment. Results are reported for 2‐chlorobutane, 2‐butanol, 2‐hexanol, and 2‐octanol at 293 K. The largest effect is observed for 2‐hexanol, the relative density difference being 1.3×10−4.

The role of the internal energy in the distribution function of a heat-conducting gas

Abstract Using a state-selective optical technique, we have measured the non-equilibrium distribution function ƒ in heat-conducting iodine gas as a function of the rotational and vibrational energy. This is the first experimental proof that in the expansion of ƒ, the contribution of polynomials quadratic in the rotational or vibrational energy is substantial.