Lurio, L. B.Rabedeau, T. A.Pershan, PeterSilvera, IsaacDeutsch, M.Kosowsky, S. D.Ocko, B. M.2013-03-011992Lurio, L. B., T. A. Rabedeau, Peter S. Pershan, Isaac F. Silvera, M. Deutsch, S. D. Kosowsky, and B. M. Ocko. 1992. Liquid-vapor density profile of helium: An x-ray study. Physical Review Letters 68(17): 2628-2631.0031-9007http://nrs.harvard.edu/urn-3:HUL.InstRepos:10357544The average liquid-vapor density profiles 〈ρ(z)〉 of thick \(^4\)He films adsorbed onto a silicon substrate were measured using x-ray reflectivity. The results are well represented by a 90%-10% interfacial width of 9.2\(\pm\)1 Å at 1.13 K which extrapolates to a T=0 K, 90%-10% interfacial width of 7.6\(\pm^{1}_{2}\) Å. The sensitivity of the measurement to the width, shape, and asymmetry of the density profile is discussed.en-USJournal Article2013-03-0110.1103/PhysRevLett.68.2628