Induced Water Condensation and Bridge Formation by Electric Fields in Atomic Force Microscopy

Abstract

ABSTRACT:We present an analytical model that explains how in humid environments the electric field near a sharp tip enhances the formation of water meniscii and bridges between tip and sample. The predictions of the model are compared with experimental measurements of the critical distance where the field strength causes bridge formation

Direct observation of self-assembled chain-like water structures in a nanoscopic water meniscus

“…Since the height of elongated water structures ranged between 2-10 nm on an oxidized silicon surface, 47 the onset distance of 12 nm can be related to the merging distance between the water structures on both tip and sample surfaces. It is not necessary for both surfaces to be applied by any strong electric field 12 or to be fully filled with water layers less than ~6 nm each at RH 30%. Because the merging meniscus formation point decreased and the oscillatory forces gradually smeared out with the humidity, 47 water films appear to form only through coalescence of elongated structures at higher humidities (>60%).…”

“…These phenomena include assembly and function of biomolecules, [1][2][3] wetting and interfacial interactions, [4][5][6] corrosion processes, 7,8 condensation and crystallization of water vapor on surfaces, 3,[8][9][10][11][12][13] and amorphous solid water in an interstellar medium. 14 It has long been postulated that water in confined spaces can have dramatically different physical properties from bulk water in extended spaces.…”

Contrast and Resolution of Nanowires in Electrostatic Force Microscopy

“…For small tip-sample distances, water condensation can play an important role in both contrast and resolution when the AFM is working in a humid environment. The values of the distances [7], [8] that can induce a water bridge between tip and sample must be taking into account when both contrast and resolution are analyzed since the presence of water can drastically modify the electric field in that region.…”

“…Its high resolution and versatility have been used to analyze several properties of solid surfaces at the nanoscale [4], [5], [6], [7], [8], [9], to induce nanometric modifications on the surfaces [10], [11] or to obtain the dielectric response of single nanowires [12], [13]. Single nanowires can be used to connect different parts of a circuit in nanoelectromechanical systems (NEMS) [14] and will play an important role in future electronics [15], [16].…”

Electrocondensation and evaporation of attoliter water droplets: Direct visualization using atomic force microscopy

“…Besides DPN, there are lithography techniques which rely on the electrolytic decomposition of the water meniscus under a biased AFM tip. Sacha et al [6] have presented an analytical model to explain the electric field-induced water condensation and bridge formation between an AFM tip and a metal surface under humid conditions. The application of a moderate tip bias of few volts generates an electric field of 10 8 -10 10 V/m which species (·OH, O -).…”