Special Issues-08-01-2015

Multiple angle incidence resolution spectroscopy (MAIRS) has proven useful for characterization of the in-plane (IP) and out of plane (OP) vibrations of thin films on solid substrates. The MAIRS technique computes the IP and OP spectra by performing a regression analysis on a series of oblique-incidence transmission spectra collected over a range of angles of a single thin film sample mounted on a transparent substrate. MAIRS replaces the more traditional technique of the collection of a transmission spectrum of a thin film on a transparent substrate, followed by collection of a reflection absorption spectrum of the same film on a metallic substrate. Often times, preparation of the same thin film on different substrates with different chemical and physical properties can be problematic. This paper will discuss details of the electromagnetic theory of MAIRS, and demonstrate its use in producing the IP and OP spectra of several thin film samples.

In recent years there has been increased use of silicones in medicine, especially for medicinal implants. Quality control of intracorporeal-used silicones is an important task for ensuring patients’ health, but it is also a challenging one. The traditional mechanical methods used for the quality control of these silicone products, like rheometric measurements, tend to waste a lot of raw material. In this study, near-infrared spectroscopy (NIRS) has been used to replace the traditional method (rheometric measurements of control samples) using rheometry only as reference method to generate different calibration models. The applicability of NIRS as non-invasive analysis method is proven and the developed calibration models for curing processes of a silicone-adhesive at different temperatures are shown.

A huge amount of information is contained in the FTIR spectra of soils in the mid infrared (MIR) region (4000 to 400 cm-1). The spectra provide an overall chemical profile of the soil, encompassing fundamental vibrations of both the organic and mineral components. Interpretation of the spectrum of individual soils can provide a powerful means of differentiating between samples and therefore has considerable potential for use in forensic applications, and indeed we have successfully used laboratory-based FTIR analysis of soil to provide evidence in forensic casework. In recent years handheld FTIR spectrometers have become available and this makes it possible for in situ or field-based FTIR analysis of soils at a crime scene. However, reliable and tested protocols are not yet available for field-based FTIR analysis of soil. This paper discusses the sampling options for field-based FTIR of soil and describes tests of the methodology we are developing, for a handheld FTIR, on soil samples tested in the context of a mock crime scene.

Combining a high precision FT-IR spectrometer with a long pathlength gas cell provides a powerful tool for analyzing trace levels of contaminants in air and other gas mixtures (Figure 1). Two important applications of this are ensuring air quality and the purity of breathing oxygen and compressed air.

Click the title above to open the Spectroscopy August 2015 FT-IR Technology Supplement, Vol 30 No s8, in an interactive PDF format.