title: Origin of adhesion in humid air.
abstract: The origin of adhesion in humid air is investigated by pull-off force measurements between nanoscale contacts using atomic force microscopes in controlled environments from ultrahigh vacuum through various humidity conditions to water. An equivalent work of adhesion (WOA) model with a simplified interface stress distribution is developed, combining the effects of screened van der Waals and meniscus forces, which describes adhesion in humid air and which self-consistently treats the contact stress and deformation. Although the pull-off force is found to vary significantly with humidity, the equivalent WOA is found to be invariant. Increasing humidity alters the nature of the surface adhesion from a compliant contact with a localized, intense meniscus force to a stiff contact with an extended, weak meniscus force.
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. dooin.kim@nist.gov
authors.forename: Doo-In
authors.initials: DI
authors.lastname: Kim
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Grobelny
authors.forename: Namboodiri
authors.initials: N
authors.lastname: Pradeep
authors.forename: Robert F
authors.initials: RF
authors.lastname: Cook
mesh_terms: D000327:Adsorption; D000388:Air; D006813:Humidity; D008956:Models, Chemical; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water