Deep Inelastic Neutron Scattering Studies of Atomic Momentum Distributions in Condensed Argon

Using deep inelastic neutron scattering, direct measurements have been made, i) of the dynamic structure factor of a series of condensed argon samples over the temperature range 18 to 85 K, near melting (for wave-vector transfers 12 to 26 Ä 1 ) and ii) of liquid neon, near 27 K (for wave-vector transfers 10.4 to 27.6 Ä 1 ) . Neutron time-of-flight chopper spectrometers were employed. Singleparticle kinetic energies, <£k>, can be obtained from the analysis of the Doppler-broadened recoil spectrum of the target particles. For argon the temperature dependence of <£k> can be compared to expectations from theory, from thermodynamic data, and from previous neutron scattering measurements on collective vibrational modes. For liquid neon the wave-vector-transfer dependence of J{y), the longitudinal momentum distribution function, is being analyzed for final-state effects.