# X-ray Induced Electrostatic Charging of Helium Films

 Title: X-ray Induced Electrostatic Charging of Helium Films Author: Penanen, K.; Pershan, Peter S.; Regan, M. J.; Silvera, Issac F. Note: Order does not necessarily reflect citation order of authors. Citation: Penanen, K., Peter S. Pershan, M. J. Regan, and Isaac F. Silvera. 1995. X-ray induced electrostatic charging of helium films. Journal of Low Temperature Physics 101(3-4): 489-494. Access Status: Full text of the requested work is not available in DASH at this time (“dark deposit”). For more information on dark deposits, see our FAQ. Full Text & Related Files: Penanen_X-ray.pdf (288.7Kb; PDF) Abstract: It is well known that free electrons can be held onto the free surface of liquid helium through either their own image charges or through the effect of an externally applied electric field. The resultant electrostatic pressure causes films to thin. We have recently measured x-ray reflectivity from static films of isotopic mixtures of helium with an intense x-ray beam in the temperature range between 0.37 K and 1.3 K. Normally, no significant thickness variation with x-ray intensity is expected over a wide range of temperatures when the film is superfluid. We have found that even modest x-ray intensities affect the thickness of films containing only trace amounts of $$^3$$He. We believe that the effect is due to x-ray produced photoelectrons, which thermalize in the vapor and then reside on the surface, attracted by both the film and a charged substrate. The temperature and concentration dependence is then due to the transport properties of the electrons at the surface. It may be possible to study the 2-D electron gas produced in this way by diffraction techniques. Published Version: doi:10.1007/BF00753342 Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:10357482 Downloads of this work: