Volume 15, Issue 3 p. 492-499
Article

The Origin of the “Snap-In” in the Force Curve between AFM Probe and the Water/Gas Interface of Nanobubbles

Yang Song,

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (PR China), Tel: (+86) 21-39194259, Fax: (+86) 21-59552394

University of Chinese Academy of Sciences, Beijing 100049 (PR China)

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Binyu Zhao,

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (PR China), Tel: (+86) 21-39194259, Fax: (+86) 21-59552394

University of Chinese Academy of Sciences, Beijing 100049 (PR China)

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Dr. Lijuan Zhang,

Corresponding Author

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (PR China), Tel: (+86) 21-39194259, Fax: (+86) 21-59552394

Shanghai Synchrotron Radiation Facility, Shanghai 201204 (PR China)

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (PR China), Tel: (+86) 21-39194259, Fax: (+86) 21-59552394Search for more papers by this author
Dr. Junhong Lü,

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (PR China), Tel: (+86) 21-39194259, Fax: (+86) 21-59552394

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Shuo Wang,

Life and Environment Science College, Shanghai Normal University, Shanghai 200234 (PR China)

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Prof. Yaming Dong,

Life and Environment Science College, Shanghai Normal University, Shanghai 200234 (PR China)

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Prof. Jun Hu,

Corresponding Author

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (PR China), Tel: (+86) 21-39194259, Fax: (+86) 21-59552394

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (PR China), Tel: (+86) 21-39194259, Fax: (+86) 21-59552394Search for more papers by this author
First published: 29 January 2014
Citations: 12

Abstract

Snap-in operation: The origin of the “snap-in” in the force curve between the atomic force microscopy (AFM) probe and the water/gas interface of a nanobubble is investigated by PeakForce quantitative nanomechanics. The phenomenon is attributed to hydrophobic interactions caused by hydrophobic contamination or surfactant absorption on the AFM probe or the nanobubble. Conventional plasma cleaning treatment is shown to remove the effect.

Abstract

The long-range attractive force or “snap-in” is an important phenomenon usually occurring when a solid particle interacts with a water/gas interface. By using PeakForce quantitative nanomechanics the origin of snap-in in the force curve between the atomic force microscopy (AFM) probe and the water/gas interface of nanobubbles has been investigated. The snap-in frequently happened when the probe was preserved for a certain time or after being used for imaging solid surfaces under atmospheric conditions. In contrast, imaging in liquids rarely induced a snap-in. After a series of control experiments, it was found that the snap-in can be attributed to hydrophobic interactions between the water/gas interface and the AFM probe, which was either modified or contaminated with hydrophobic material. The hydrophobic contamination could be efficiently removed by a conventional plasma-cleaning treatment, which prevents the occurring of the snap-in. In addition, the adsorption of sodium dodecyl sulfate onto the nanobubble surface changed the water/gas interface into hydrophilic, which also eliminated the snap-in phenomenon.