Adhesion Forces between Surface-Modified AFM Tips and a Mica Surface

Eastman, Timothy; Zhu, Da‐Ming

doi:10.1021/la9504220

Cited by 163 publications

(132 citation statements)

References 15 publications

Supporting

Mentioning

128

Contrasting

Order By: Relevance

“…Water condenses into the gap at the contact region between hydrophilic particles. This is with AFM [69,119,[190][191][192][193][194][195][196][197][198]. Many experiments showed a significant dependency of the adhesion force on the relative humidity [40,52,54,56,57,183].…”

Section: Influence Of Humidity On Adhesionmentioning

confidence: 92%

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

et al. 2006

View full text Add to dashboard Cite

To optimize the handling of fine powders in industrial applications, understanding the interaction forces between single powder particles is fundamental. The forces between colloidal particles dominate the behavior of a great variety of materials, including paints, paper, soil, and many industrial processes. With the invention of the atomic force microscope (AFM), the direct measurement of the interaction between single micron-sized particles became possible. The adhesional contact between a particle and a substrate is a parameter for analyzing pull-off force data generated by AFM. The aim of this study was to understand surface interactions between fine particles. I measured the adhesion forces between AFM tips or particles attached to AFM cantilevers and different solid samples. Smooth and homogeneous surfaces such as silicon wafer, mica, or highly oriented pyrolytic graphite (HOPG), and more rough and heterogeneous surfaces such as iron particles or patterns of TiO 2 nanoparticles on silicon wafer were used. First, I addressed to the wellknown issue that AFM adhesion experiment results show wide distributions of adhesion forces rather than a single value. My experimental results show that variations in adhesion forces comprise fast (i.e., from one force curves to the next) random fluctuations and slower fluctuations, which occur over tens or hundreds of consecutive measurements. Slow fluctuations are not likely to be the result of variations in external factors such as lateral position, temperature, humidity, and so forth because those were kept constant. Even if two solid bodies are brought into contact under precisely the same conditions (same place, load, direction, etc.) the result of such a measurement will often not be the same as for the previous contact. The measurement itself will induce structural changes in the contact region which can change the value for the next adhesion force measurement.In the second part I studied the influence of humidity on the adhesion of nanocontacts. Humidity was adjusted relatively fast to minimize tip wear during one experiment. For hydrophobic surfaces, no signification change of adhesion force with humidity was observed. Adhesion force-versus-humidity curves recorded with hydrophilic surfaces either showed a maximum or continuously increased. I demonstrate that the results can be interpreted with simple continuum theory of the meniscus force. The meniscus force is calculated based on a model that includes surface roughness and takes into account different AFM tip (or particle) shapes by a two-sphere-model.Experimental and theoretical results show that the precise contact geometry has a critical influence on the humidity dependence of the adhesion force.Changes of tip geometry on the sub-10-nm length scale can completely change adhesion force-versus-humidity curves. Our model can also explain the differences between earlier AFM studies, where different dependencies of the adhesion force on humidity were observed.Keywords: Atomic force microscopy (AFM), cantile...

show abstract

Section: Influence Of Humidity On Adhesionmentioning

confidence: 92%

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Many experiments are in the limit where the drop dimensions are much smaller than the tip radius, but much larger than the separation h. In this limit (R |r 2 | |r 1 |), F cap is independent of both h and the drop volume V l [30]. As V l increases, the increases in a t and a s are compensated for by the decrease of κ and thus p. This condition frequently applies for granular materials held together by liquid bridges formed via capillary condensation, making their mechanical properties relatively insensitive to the relative humidity of the environment or the addition of extra nonvolatile liquids [10,21]. However, our simulations are generally in a different limit where the drop and tip have comparable dimensions and F cap depends on both h and V l .…”

Section: Macroscopic Theory Of Capillary Forcesmentioning

confidence: 99%

“…They play a major role in nanoscopic sliding friction and lead to a nontrivial velocity dependence of friction [15][16][17][18][19]. Many previous experiments also show that when an atomic force microscope (AFM), or more generally any small probe, is used to examine a hydrophilic surface in a humid environment, a major contribution to the tipsurface interaction is from the capillary forces associated with the water meniscus bridging the tip and surface [15,[20][21][22][23][24][25][26][27][28]. The geometry in these experiments can be reasonably approximated as a liquid bridge connecting a spherical tip of certain size and a flat surface.…”

Section: Introductionmentioning

confidence: 99%

“…Here the presence of the surfaces shifts the phase diagram of the fluid to favor the liquid phase [14]. Capillary condensation is responsible for the formation of water menisci in the AFM experiments mentioned above [15,[20][21][22][23][24][25][26][27][28]. The capillary pressure inside the liquid bridge is fixed by the relative humidity of the vapor phase, and the volume of the liquid bridge depends on the size of the gap.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Capillary adhesion at the nanometer scale

Cheng

Robbins

2014

Phys. Rev. E

View full text Add to dashboard Cite

Molecular dynamics simulations are used to study the capillary adhesion from a nonvolatile liquid meniscus between a spherical tip and a flat substrate. The atomic structure of the tip, the tip radius, the contact angles of the liquid on the two surfaces, and the volume of the liquid bridge are varied. The capillary force between the tip and substrate is calculated as a function of their separation h. The force agrees with continuum predictions based on macroscopic theory for h down to ∼5 to 10 nm. At smaller h, the force tends to be less attractive than predicted and has strong oscillations. This oscillatory component of the capillary force is completely missed in the macroscopic theory, which only includes contributions from the surface tension around the circumference of the meniscus and the pressure difference over the cross section of the meniscus. The oscillation is found to be due to molecular layering of the liquid confined in the narrow gap between the tip and substrate. This effect is most pronounced for large tip radii and/or smooth surfaces. The other two components considered by the macroscopic theory are also identified. The surface tension term, as well as the meniscus shape, is accurately described by the macroscopic theory for h down to ∼1 nm, but the capillary pressure term is always more positive than the corresponding continuum result. This shift in the capillary pressure reduces the average adhesion by a factor as large as 2 from its continuum value and is found to be due to an anisotropy in the pressure tensor. The component in the plane of the substrate is consistent with the capillary pressure predicted by the macroscopic theory (i.e., the Young-Laplace equation), but the normal pressure that determines the capillary force is always more positive than the continuum counterpart.

show abstract

“…Second, ductile tips are preferred because they do not break when being pressed multiple times on the sample. Third, the tip material is important, because the adhe- sion forces strongly depend on the involved materials 25 . To our experience these requirements are best met by metal coated silicon tips, which are commercially available (we used Au and Pt/Ti coated cantilevers from MicroMasch).…”

Section: The Pick-and-place Proceduresmentioning

confidence: 99%

A scanning probe-based pick-and-place procedure for assembly of integrated quantum optical hybrid devices

Schell

Kewes

Schröder

et al. 2011

Review of Scientific Instruments

View full text Add to dashboard Cite

Integrated quantum optical hybrid devices consist of fundamental constituents such as single emitters and tailored photonic nanostructures. A reliable fabrication method requires the controlled deposition of active nanoparticles on arbitrary nanostructures with highest precision. Here, we describe an easily adaptable technique that employs picking and placing of nanoparticles with an atomic force microscope combined with a confocal setup. In this way, both the topography and the optical response can be monitored simultaneously before and after the assembly. The technique can be applied to arbitrary particles. Here, we focus on nanodiamonds containing single nitrogen vacancy centers, which are particularly interesting for quantum optical experiments on the single photon and single emitter level.

show abstract

Adhesion Forces between Surface-Modified AFM Tips and a Mica Surface

Cited by 163 publications

References 15 publications

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

Capillary adhesion at the nanometer scale

A scanning probe-based pick-and-place procedure for assembly of integrated quantum optical hybrid devices

Contact Info

Product

Resources

About