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P Verkerk

Publications and source records attributed to P Verkerk.

At least 19 recordsLinked to original sources
PubMed2001

Neutron Brillouin scattering study of collective dynamics in a dense He-Ne gaseous mixture.

The dynamic structure factor S(k,omega) of a 77% He and 23% Ne gaseous mixture at T = 39.3 K and total number density n = 15.8 nm(-3) has been measured by inelastic neutron scattering at small angles. In the range of wave vectors studied, 0.7<k/nm(-1)<1.8, we find clear side peaks at frequencies following the hydrodynamic sound dispersion c k of the binary mixture (with c the adiabatic sound speed in the mixture). Surprisingly, neither fast modes nor a transition from normal to fast sound are observed in the above low- k region, indicating that hydrodynamic behavior persists up to k values which are larger than those predicted by theories and computer simulations.

Journal Article↗
PubMed2000

Quantum effects on liquid dynamics as evidenced by the presence of well-defined collective excitations in liquid para-hydrogen

The origin of the well-defined collective excitations found in liquid para-H2 by recent experiments is investigated. The persistence of their relatively long lifetimes down to microscopic scales is well accounted for by calculations carried out by means of path-integral-centroid molecular dynamics. In contrast only overdamped excitations are found in calculations carried within the classical limit. The results provide fully quantitative evidence of quantum effects on the dynamics of a simple liquid.

Journal Article↗