Interfacial Characterization

Compression/expansion isotherms of monolayers provide a wealth of information about macroscopic physical behaviour as related to chemical structure. However, many questions remain about the detailed structure and behaviour of the interface. For example, the structure of a floating monolayer is often not uniform. Instead, ordered domains form over relatively large areas. The Brewster Angle Microscope (BAM 300) exploits differences in refractive index between the domains to provide microscopic maps of surface structure.


	BAM image of the lipid dimyristoylphosphatidylethanolamine (DMPE) on pure water (horizontal scale circa 600 micron)

Monolayers are often studied as models for more complex systems, such as bilayers (e.g. cell membranes), foams or emulsions. One of the critical properties of monolayers in real systems is the dynamic response to applied mechanical stress. This is referred to as "interfacial rheology" and can now be studied with unparallelled sensitivity using the new Interfacial Shear Rheometer, ISR 400. This instrument uses magnetism in the form of two Helmholtz coils to control the shearing motion of a magnetic needle floating at the interface. The position of the needle is determined via a digital camera, providing actual position versus applied force and therefore shear stress versus shear strain.

Accessing the chemical nature of the monolayer can be achieved using the reflective IR technique referred to as PM-IRRAS. The user-friendly PMI 550 allows for example, determination of chain tilt in lipid layers and progress of surface specific reactions.

Whatever monolayer system you are studying, these three tools can provide you with the crucial insights you are looking for!

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Brewster Angle Microscope
	KSV Optrel BAM 300 Observe 2-dimensional structure in monolayer films, either at the air-water interface, or on a dielectric solid. State-of-the-art laser and CCD-camera technology coupled with intuitive software ensure trouble-free and quick operation.
	KSV MicroBAM An affordable solution for non-invasive imaging of monolayers at the air-water interface.
Interfacial Shear Rheometer
	ISR 400 A unique instrument that measures the shear properties of fluid interfaces with unparallelled sensitivity.
PM-IRRAS
	PMI 550 A user friendly spectrometer for rapid surface specific characterization of floating and deposited monolayers.
KSV SPOT
	KSV SPOT brochure (pdf) Surface Potential measuring head for Langmuir film characterization.

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