Brewster Angle Microscopes (BAM) enable visualization of monolayers, typically at the air-water interface in a Langmuir Trough. They create an image of the surface by detecting changes in the refractive index of the water surface in the presence of surfactant molecules. This provides information on homogeneity, phase behavior and film morphology.
Features & Benefits
KSV NIMA BAM
KSV NIMA MicroBAM
KSV NIMA offers two different Brewster Angle Microscopes, the advanced KSV NIMA BAM and the compact KSV NIMA MicroBAM.
KSV NIMA BAM
The KSV NIMA BAM represents the latest in BAM instrumentation, allowing high resolution and fully focused real-time imaging of monolayers. The KSV NIMA BAM provides completely undistorted images unlike other BAMs. A precise motorized vertical lift allows fine positioning to focus the water surface. An active isolation system is integrated to the KSV NIMA BAM to eliminate disturbing environmental vibration from air conditioning, traffic etc.
A high performance camera and dedicated calibration algorithms allow quantitative measurements of reflectivity for monitoring adsorption kinetics or thickness variation. The KSV NIMA BAM is equipped with a motorized analyzer to visualize optical anisotropy due to long-range molecular orientation order in monolayers.
The software offers advanced and comprehensive image analysis and processing functionalities. A Langmuir trough can be used together with the KSV NIMA BAM for control over the monolayer packing density and recording of surface pressure. The compatible KSV NIMA Langmuir and Langmuir-Blodgett Deposition Trough Large are the recommended systems. A PC is included with the instrument.
KSV NIMA MicroBAM
The KSV NIMA MicroBAM and KSV NIMA Stand-Alone MicroBAM are easy-to-use, entry level instruments for non-invasive imaging of mono-molecular layers at the air-water interface. The excellent image quality and good lateral resolution make them ideal instruments for the visualization of morphological film parameters (e.g. compressed film homogeneity, domain size, shape and packing). Real-time observation and recording of film structure enables dynamic activity to be captured.
Both the KSV NIMA MicroBAM and KSV NIMA Stand-Alone MicroBAM can be used with most KSV NIMA Langmuir and Langmuir-Blodgett Troughs for automatic image measurements as a function of time or surface pressure. Both instruments are easy to set up with the measurement head height adjustment either motorized, KSV NIMA MicroBAM, or manual, KSV NIMA Stand-Alone MicroBAM. Both instruments have a safety key interlock for the BAM laser.
The KSV NIMA Stand-Alone MicroBAM can also be used with most Langmuir and Langmuir-Blodgett Troughs from other manufacturers as well as freestanding vessels. The KSV NIMA Stand-Alone MicroBAM connects directly to the computer via USB making it remarkably easy to setup and use.
KSV NIMA BAM |
KSV NIMA MicroBAM
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|
Measurement |
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Angle-of-incidence range (°) |
52…57, motorized |
53, fixed |
Angle-of-incidence resolution (°) |
0.001 | – |
Light source power (mW) |
50 | 50 |
Light source wavelength (nm) |
658 | 659 |
Image resolution (µm) |
2 (horizontal image direction)1 |
12 (horizontal image direction, center)1 |
Field of view (µm) |
720×400 | 3600×4000 |
Polarizer |
Glan-Thompson prism, motorized | Fixed2 |
Polarizing resolution (°) |
0.001 | – |
Analyzer |
Motorized | Fixed |
Analyzing resolution (°) |
0.001 | – |
Camera |
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Type |
CCD | USB |
Resolution (px) |
1360×1024 | 640×480 |
Framerate (fps) |
20-35 | 30 |
Adjustable exposure time and gain |
√ | √ |
AVI video recorder |
√ | – |
Image processing |
||
Background compensation |
Automatic | – |
Geometric image deformation for unskewed images |
√ | – |
Image resizing |
– | √ |
Scale bar overlay |
√ | – |
Contrast enhancement |
√ | Profile |
Image filtering |
√ | √ |
Various image formats |
√ | – |
Particle size determination |
Advanced | √ |
Hardware |
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Instrument dimensions (L×W×H, cm) |
85×47×65 | 22×27.7×40.2 |
Measuring head dimensions (L×W×H, cm) |
45×10×25 | 5.7×16.2×7.2 |
Power supply (V, Hz) |
100-240, 50/60 | 100-240, 50/60 |
Weight (kg) |
45 | 10 |
Compatibility with L & LB Troughs |
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Medium |
– | √ |
Large |
√ | √ |
High Compression |
– | √ |
Alternate |
– | √ |
Brewster Angle Microscope
Brewster Angle Microscopes (BAM) enable the visualization of Langmuir monolayers or adsorbate films at the air-water interface. In conjunction with a Langmuir Trough it is possible to study:
Monolayer/film behavior. It is possible to observe phase changes, phase separation, domain size, shape and packing.
Monolayer/film homogeneity. When combined with a KSV NIMA L & LB Trough, observation can be performed during compression/expansion at known surface pressures.
Influence of sub-phase conditions on film structures. Observe and study monolayer/film behavior and formation in different sub-phase conditions including salt concentrations, pH and temperature etc.
Monitoring of surface reactions. For example, photochemical reactions, polymerization reactions as well as enzyme kinetics can be followed in real-time.
Monitoring and detection of surface active materials. For example protein adsorption and nanoparticle flotation. BAMs are primarily designed for the air-water interface. However under some conditions the KSV NIMA BAM can be used for other interfaces such as air-glass.
Application examples
Chemical exfoliation of graphite in the production of graphene
Chemical exfoliation of graphite is recognized as one of the most potential methods for producing graphene in industrial scale. The result of the exfoliation process is graphene oxide, which is known to disperse well in water due to its ionizable –COOH groups. However, the basal plane of graphene is essentially a network of hydrophobic benzene rings. In a study by Kim and coworkers, the properties of graphene oxide were investigated by examining the amphiphilic nature of the molecule in a Langmuir trough.
Langmuir isotherms and Brewster angle microscopy were used to examine the properties and observe the formation of graphene oxide sheets at air-water interfaces. The study showed how monolayer imaging can improve solution processing and to help finding the optimal deposition parameters for graphene oxide materials.
Structure of asphaltene model compounds
Asphaltenes, a class of compounds in crude oil, are known to stabilize emulsions by forming elastic interfacial films. Despite the ongoing research regarding the structure and functional groups of these polyaromatic hydrocarbons, the exact chemical composition remains unknown.
Langmuir isotherm experiments show that the presence of acidic groups in asphaltene molecules is crucial for their film forming properties and interfacial activity. The packing morphology was further examined using a Brewster angle microscope. The study shows how Brewster angle microscopy can be used to correlate the structural properties and different phase transitions of Langmuir monolayers at air-water interfaces.