Van der Waals Forces between Quartz andnhyphen;Heptane

摘要

The room temperature adsorption isotherm ofnhyphen;heptane on an AThyphen;cut quartz crystal has been measured in the region of very high coverages (six to 15 monolayers). The isotherm in this region may be represented by the equation lnP=C+Dgr;psgr;/kTd3, where Dgr;psgr;/d3, is interpreted as the difference between the potential energy of a heptane molecule at a distancedfrom a quartz surface and that of a heptane molecule at the same distance from a liquid heptane surface. A value of Dgr;psgr;/kTof 725 Aring;3is obtained.