A measure of the effective electric-dipole polarizability of argon

The electric dipole polarizability has been determined in a unique way. Binary complexes of argon with transition metal cations have been studied by optical spectroscopy. The vibrational structure of electronic transitions near the dissociation limit of the upper state quantifies the forces between the atoms. The polarizability of argon is determined from the charge-induced-dipole force in four different molecular ions as 1.49 ± 0.10 Å3. This is lower than the accepted value by 9%. This discrepancy may imply that the multipole expansion of the charge distortion does not have linearly independent coefficients in the field of an ion at close range. Induced higher-order moments appear to reduce the effective dipole polarizability.