EFFECT OF TEMPERATURE ON THE FORMATION OF A BOUND-STATE OF POSITRONIUM WITH NITROBENZENE AND ON THE RELATED HYPERFINE INTERACTION PARAMETERS

The strong magnetic field effect on the chemical bound-state formation of positronium with nitrobenzene in n-hexane previously studied at 294 K has been further examined as a function of temperature, from 264 to 328 K. The model proposed before to explain the data, implying the definition of triplet and singlet positronium bound-state, appears to be valid at all temperatures studied. The variation with temperature of the parameters descriptive of the bound-state are derived; the hyperfine splitting is constant at 1.06 X 10(-5) eV, while the contact density parameter, eta(c) shows an abrupt change from 0.43 to 1.56 between 286 and 292 K. These experiments give new insight on the structure of the bound-state formed, which may be considered as a charge-transfer complex.