Exoscan FTIR Transforms From Versatile Benchtop Lab Spectrometer to Powerful, Handheld, At-Site Analyzer

Introduction

Infrared spectroscopy has long been recognized as a selective and sensitive technique, however, with current benchtop infrared spectrometers, it is often necessary to remove a sample from a large object and bring the small piece to the spectrometer located in the laboratory. Thus, a potentially non-destructive methodology for large objects becomes a destructive one due to the necessity of small sample size coupled with the location of the FTIR system.

The availability of A2 Technologies’ Exoscan™ changes how true non-destructive analysis is carried out, since Exoscan can be brought to the sample, rather than the reverse. Though size and portability is important for these applications, equally important is overall spectroscopic performance, since measurements such as surface analysis, for example, can be very demanding. Exoscan has a performance envelope equivalent to or better than analytical benchtop systems and, with the availability of interchangeable sample interfaces and docking station, is a versatile system which can easily be used for routine analysis and methods development in the lab, as well as taken to the field for on-site analysis.

Sample Interfaces

The Exoscan can measure surface samples with four different techniques: internal reflectance (ATR), specular reflectance, grazing angle reflectance and diffuse reflectance. The four interchangeable sample interfaces are shown in Figure 1 and provide a wide variety of options for many different sample types.

• The ATR interface is ideal for the analysis of solids, liquids, pastes and gels. The interface uses a diamond ATR element which makes it impervious to corrosion and scratching.
   
• The Specular reflectance enables the analysis of films and coatings on reflective metal surfaces such as aluminum or steel. The angle of incidence is 45 degrees. The infrared energy either passes completely through the sample before being reflected by the substrate, or the energy is reflected off the front surface of a smooth sample.
   
• The grazing angle reflectance interface is similar in concept to the specular reflectance interface, but differs in the angle of incidence. The Exoscan grazing angle has a nominal angle of 82 degrees, which is ideal for the analysis of very thin (submicron) films, such as trace contamination on reflective metal surfaces.
   
• The diffuse reflectance interface is used for samples that tend to scatter light such as rough surfaces or granular materials. Samples can be measured without sample preparation and thus samples of geological interest or carbon fiber rich composite material are best measured by diffuse reflectance.

Exoscan Docking Station

The docking station converts the handheld Exoscan into a versatile benchtop instrument (Figure 2), and allows development of methods by collecting data on representative samples before taking the instrument out to the field. Thus, Exoscan is effective for analyzing routine lab samples and method development as well as at-site analysis or troubleshooting.

Conclusion

A high performance, handheld, portable FTIR spectrometer provides true non-destructive analysis of a wide range of samples, from routine powders and solids to large, immovable objects. The versatility of the Exoscan arises from its performance, interchangeable sampling interfaces and innovative docking station and enables the system to provide significant value in laboratory and field environments.