A remark on the time-dependent pair distribution

Abstract

After recalling the classical work of Zernike and Prins on the pair distribution function of a liquid or gas and its role in X-ray scattering theory, one briefly discusses the time-dependent generalization of this distribution function, which is of special interest for neutron scattering. In line with an earlier result of Fano, one shows that the imaginary part of the time-dependent pair distribution directly describes the local density change produced in a liquid or gas by the presence of a neutron.