PROBING OSCILLATORY HYDRATION POTENTIALS USING THERMAL-MECHANICAL NOISE IN AN ATOMIC-FORCE MICROSCOPE

Citation
Jp. Cleveland et al., PROBING OSCILLATORY HYDRATION POTENTIALS USING THERMAL-MECHANICAL NOISE IN AN ATOMIC-FORCE MICROSCOPE, Physical review. B, Condensed matter, 52(12), 1995, pp. 8692-8695
Citations number
31
Categorie Soggetti
Physics, Condensed Matter
ISSN journal
01631829
Volume
52
Issue
12
Year of publication
1995
Pages
8692 - 8695
Database
ISI
SICI code
0163-1829(1995)52:12<8692:POHPUT>2.0.ZU;2-M
Abstract
Intermolecular forces between surfaces and molecules in aqueous soluti ons at distances below a few nanometers are critically important to th e functioning of many systems, from colloidal to tribological and from geological to biological. These forces are not, however, well underst ood at present. We have made measurements of multiple, metastable stat es near the hydrophilic cleavage planes of the ionic crystals calcite (CaCO3) and barite (BaSO4) using a low-noise atomic-force microscope. The interaction potential of the cantilever tip is determined using th e Boltzmann relation on histograms of the tip position as it hops betw een the metastable states, and is found to be oscillatory, indicating layering of the solvent at the tip or sample. These oscillations are s paced from 0.15 to 0.30 nm apart and are of order 5 X 10(-21) J in amp litude, which is comparable to the thermal energy k(B)T=4 X 10(-21) J at room temperature.