The quadrupole moment of chlorine

The molecular quadrupole moment of chlorine was determined by measuring the refractive index anisotropy induced in the gas by an electric field gradient. A value of 5·0 ± 0·5 × 10-26 esu was found (for quadrupoles, 1 esu = 3·3 × 10-14 coulomb metre2). The virial coefficient data for the gas were fitted to values calculated for a potential based on a diatomic model that includes the interaction of the molecular quadrupoles; parameters obtained in this way for the interaction well depth and molecular size are reported and compared with those used for Cl2 by other workers.