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Why can surface force instruments reveal how water molecules dance between molecules?
The scientific community continues to explore the mysteries of the microscopic world, and the Surface Force Instrument (SFA) is one of the key tools. The main function of SFA is to measure the interaction force between two surfaces, especially water molecules and their intermolecular interactions. Its design was originally inspired by David Tabor and R.H.S. Winterton at the University of Cambridge, and later in the 1970s, J.N. Israelachvili extended the technology to liquid environments, especially the aqueous phase. As this technology advances, scientists are able to better understand the behavior of water molecules in different media.
Surface force instruments can unlock the mysteries of the dance of water molecules, allowing scientists to observe how water molecules interact with each other.
Basic operating principles of surface force instruments
Surface force instruments use optical interference technology to measure the distance between two surfaces using fine positioning elements. This technology is able to resolve distances to a precision of 0.1 nanometers and detect forces as small as 10^-8 Newtons. Unlike atomic force microscopy, SFA is better suited to measuring interactions between surfaces and can accurately measure forces over a longer range.
Jumping method and resonance method
SFA has two main measurement methods, namely the jump method and the resonance method. In the jumping method, the upper cylindrical surface is fixed to a pair of cantilever springs. When the lower cylindrical surface approaches, the two suddenly come into contact and "jump" together. This process allows precise measurement of the distance between surfaces.
By observing how water molecules jump across different distances, scientists can reveal its underlying physical properties.
The resonance method can reduce the interference caused by vibration and measure the force between different surfaces through vibration of a known frequency. Performing this measurement in a vacuum environment allows for more accurate data.
Solvent mode and dynamic mode
With the advancement of technology, SFA's measurement capabilities have gradually expanded to various media and conditions. Most early experiments were performed in air or vacuum, but now water or other solvents can be introduced into the measurement process. The move allows scientists to better understand how water molecules behave in biological membranes or proteins.
This advancement in SFA opens a new chapter in the study of biomolecular interactions, revealing the vibrational and structural forces of water molecules.
In addition, the dynamic mode of SFA can measure the viscosity and viscoelastic properties of fluids and time-dependent interactions between surfaces, further making it favored for surface science applications.
Applications in the laboratory
Laboratories around the world have made surface force instruments an important part of their surface science research equipment. Researchers can use this instrument to explore the properties of new materials, surface protection technologies, and biomedical issues. In this process, the "dance" of water molecules is no longer an abstract concept, but a series of quantifiable data, thus providing a brand new window for the scientific community.
This technique not only provides a deep understanding of the interactive behavior of water molecules, but also has the potential to revolutionize materials science.
Currently, with the further development of technology, the potential of SFA for exploring nanoscale phenomena and behaviors continues to expand. How will these tiny interactions affect our understanding of the physical world? Maybe they will bring us more surprises and inspirations in the future?
