Brewster Angle Microscope

Brewster Angle Microscopes (BAMs) enable visualization of monolayers, typically at the air-water interface in a Langmuir Trough. By detecting changes in the refractive index of the water surface in the presence of surfactant molecules, BAMs provide information on homogeneity, phase behavior and film morphology without the need for any external agents such as fluorescent dyes which could interfere with the Langmuir layer.

Application overview

Brewster Angle Microscopes (BAMs) enable the visualization of Langmuir monolayers or adsorbate films at the air-water interface for example as a function of packing density.

Pre-deposition Langmuir-Blodgett layer quality check

  • Monolayer/film homogeneity. When combined with a KSV NIMA L & LB Trough, observation can be performed during compression/expansion at known surface pressures. Verifying the homogeneity of the monolayer already prior to deposition will speed up the research considerably.
  • Optimizing the deposition parameters. For a high quality LB coating, the measurement parameters such as compression speed, waiting times, temperature and subphase content need to be optimized. With BAM it is easy to study the effects of these parameters and choose the optimal conditions.

Langmuir layer structure and behavior studies

  • Monolayer/film behavior. It is possible to observe phase changes, phase separation, domain size, shape and packing.
  • 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.

 

Features & Benefits

KSV NIMA BAM

  • The best resolution (2 µm) and image quality in the field of Brewster Angle Microscopy and provides real-time and fully focused sample visualization at 20-35 fps.
  • Domain size and film thickness analysis integrated into the same software.
  • Adjustable incident angle (52-57°) enabling measurements with dielectric solid substrates like glass or quartz.
  • Imaging of anisotropic layers with the motorized analyzer.
  • On-line automatic background subtraction for an optimal image.
  • Easy integration with KSV NIMA L & LB Trough Large.
  • Video and image recording options.
  • Includes an active antivibration system for reducing the vibrations coming from the measurement environment.

KSV NIMA MicroBAM

  • Good resolution (12 µm) and large field of view for film homogeneity and domain size studies.
  • Capture and save still images of monolayers.
  • Can be set to take pictures automatically as a function of time or surface pressure.
  • Compact design, small footprint.
  • Simple, intuitive operation.
  • Compatible with most Langmuir troughs and Langmuir-Blodgett troughs.
  • Optimal for routine LB film homogeneity check prior to deposition.

Product details

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 BAM
 

KSV NIMA MicroBAM

The KSV NIMA MicroBAM is easy-to-use, entry level instruments for non-invasive imaging of mono-molecular layers at the air-water interface. The good image quality and lateral resolution make it an ideal instrument 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.

The KSV NIMA MicroBAM can be used with most KSV NIMA Langmuir and Langmuir-Blodgett Troughs, to provide real-time image measurements as a function of time or surface pressure. The KSV NIMA MicroBAM connects directly to the computer via USB making it remarkably easy to setup and use.

 
KSV NIMA MicroBAM
 

Technical specifications

 
KSV NIMA BAM
KSV NIMA MicroBAM

Measurement

  
Angle-of-incidence range (°)

52…57, motorized

53, fixed
Angle-of-incidence resolution (°)
0.001
Light source power (mW)
5050
Light source wavelength (nm)
658659
Image resolution (µm)

2 (horizontal image direction)1

12 (horizontal image direction, center)1
Field of view (µm)
720×4003600×4000
Polarizer
Glan-Thompson prism, motorizedFixed2
Polarizing resolution (°)
0.001
Analyzer
MotorizedFixed
Analyzing resolution (°)
0.001

Camera

  
Type
CCDUSB
Resolution (px)
1360×1024640×480
Framerate (fps)
20-3530
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

  
Instrument dimensions (L×W×H, cm)
85×47×6522×27.7×40.2
Measuring head dimensions (L×W×H, cm)
45×10×25 5.7×16.2×7.2
Power supply (V, Hz)
100-240, 50/60100-240, 50/60
Weight (kg)
4510

Compatibility with L & LB Troughs

 
Medium
Large
High Compression
Alternate

1According to Rayleigh’s criterion

2P-polarization of the incident beam

Application examples

Deposition parameter optimization for graphene oxide

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. In a study by Kim and coworkers (Kim et al., ‘J of American Chemical Society’ (2010), 132, pp. 8180-8186), 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. ‘Langmuir’(2008), 24 (16), pp 8742-8751.

For more information, see Application Note 9 — Imaging the Structure of Thin Films: Brewster Angle Microscopy.