Infrared (IR) Spectroscopy

An interview with Allison Stelling, a recent PhD from Prof. Peter Tonge's group at Stony Brook University in New York, exploring the use of IR spectroscopy for use in intraoperative diagnostics during brain surgery.

In these types of IR imaging, various factors contribute to the observed resolution. These factors are illustrated with images of materials with known structures.

Highlights of recent advances in three major areas of molecular spectroscopy: infrared (IR), Raman, and fluorescence.

Everyone loves a list, and the editors of Spectroscopy are no exception! In 2013, Spectroscopy covered a wide array of topics throughout the year to bring you the most relevant information for your work, on topics ranging from selecting the right ICP-MS system to deciding which Raman technique is right for you, from our annual salary survey to calibration transfer. Here is a list of 13 popular articles and columns from 2013

In a recent interview, Rohit Bhargava, winner of the 2013 Craver Award from the Coblentz Society, discusses current trends in IR spectroscopic imaging, including application-specific instrumentation, improvements in data interpretation, and identifying relationships between structure and spectra.

Click here to view the complete Wavelength newsletter from October 15, 2013.

Fourier transform infrared (FT-IR) spectroscopy has been used to identify unknown materials, determine the quality or consistency of a sample, and determine the amount of components in a mixture. Gary Small, of the Department of Chemistry and Optical Science and Technology Center at the University of Iowa, spoke to Spectroscopy about his work using passive FT-IR remote sensing measurements.

A novel infrared-based method that permits fast and impartial analysis of detergent removal from biological samples is presented.

The Mid-Infrared Technologies for Health and the Environment (MIRTHE) center hosted a workshop titled “Air Quality Monitoring Related to Energy Extraction†on Friday, August 9, 2013 at Princeton University (Princeton, New Jersey). The workshop was well attended and highlighted some of the key issues surrounding energy extraction.

Combined experimental and computational investigation methods are used to estimate the defect density on a rutile surface, indicating its catalytic activity.

In these types of IR imaging, various factors contribute to the observed resolution. These factors are illustrated with images of materials with known structures.

The use of imaging to study the reaction process involved in the curing of a cyanoacrylate adhesive is investigated.

A method is presented that demonstrates the ability to measure 11-Ã… layers, with potential for sub-1-Ã… determinations.

Polystyrene film is useful for routine checking of FT-IR spectrometer performance, but variations in film thickness and scattering can cause large variations in the results.

Click here to view the complete Wavelength newsletter from October 16, 2012.

Fourier transform infrared (FT-IR) spectroscopic imaging is a highly versatile technique that can be applied to a wide range of systems. This article summarizes some of the recent efforts developing applications of FT-IR imaging for microfluidics. The main advantage of FT-IR imaging compared to traditional imaging methods is that it is a label-free imaging technique.

Fourier transform infrared (FT-IR) spectroscopic imaging is a highly versatile technique that can be applied to a wide range of systems. This article summarizes some of the recent efforts developing applications of FT-IR imaging for microfluidics. The main advantage of FT-IR imaging compared to traditional imaging methods is that it is a label-free imaging technique.

The well-established technique of Fourier transform infrared (FT-IR) spectroscopy offers analytical capabilities for diverse applications, and chemometrics and spectral interpretation software are important elements of the technique.

The beginning of the age of Fourier transform infrared (FT-IR) spectroscopy meant the availability of digital spectra and opened the possibility of using computers to compare a single spectrum against a reference database containing thousands of spectra, thereby allowing enormous efficiency gains in the comparison of unknown spectra to reference materials. Various algorithms can be used to create a hit quality index (HQI), which is a measure of how well the query spectrum compares against each reference spectrum.

Infrared reflection spectroscopy is a tool that can be used to study coated plastics, but the spectra can show unexpected features. In this report, we calculate the specular reflectance for a flat surface of two different polymers as well as how their spectra change when the other polymer is added as a film with a thickness of up to 2.5 ?m. One of the unusual phenomena we observe is that "derivative"-shaped substrate bands invert in sign as the other polymer is added as a coating. We also show how the reflection of the surface changes and becomes polarized as the angle of incidence increases.

Self-assembled monolayers (SAMs) can be applied in a variety of technical areas. Infrared characterization of these materials is a challenge because of the low concentrations on the surfaces. This article reviews the sampling methods for characterization and presents data comparing the different approaches.

The micro attenuated total reflectance (ATR) chemical imaging of polymers, in particular polymer laminates, typically requires significant pressure to ensure good sample-to-ATR crystal contact. For thin cross-sectioned materials, ensuring structural rigidity against this pressure requires significant sample preparation, such as resin embedding, cutting, and polishing.

A review of the application of IR spectroscopy for the analysis of color components in winemaking, and the contribution of spectral preprocessing to improve the multivariate calibration.

By combining atomic force microscopy (AFM) and infrared (IR) spectroscopy, one can attain spatial resolution improvements of two orders of magnitude over traditional IR spectroscopy.

The series on classical least squares continues with a comparison of experimental results and theoretical expectations.

Case studies involving fouling and product quality illustrate the effective use of this method.

Continued discussion of the classical least squares approach to calibration, with a focus on the reconstruction of mixtures

How can you navigate the maze of choices for detecting molecular vibrations with mid-infrared (IR), near IR (NIR), and visible (Raman)? Understanding what is being measured, how it is measured, and the advantages and disadvantages of each technique, will help.

When combined with the rapid scan speeds of modern instruments, Fourier-transform infrared (FT-IR) spectroscopy provides a powerful real-time method for monitoring chemical changes (for example, the optical adhesive caused by illumination of a UV lamp). This article describes the characterization of several adhesives used in an optical assembly. Several different approaches to measuring the rate of change during the curing experiment are described. As the number of uses for UV curing and photopolymerization increases, real-time FT-IR should play a major role in characterizing these new materials and products.

Process analytical technology (PAT) and hot-melt extrusion (HME), commonplace in the food and polymer industries, are becoming increasingly deployed in the pharmaceutical industry. Herein the application of in-line, transmission mode, Fourier-transform near-infrared (FT-NIR) spectroscopy to the HME manufacturing platform for a drug product in development is detailed. NIR spectroscopy and partial least squares (PLS) models were developed for real-time active pharmaceutical ingredient (API) loading (%wt/wt) and surfactant loading predictions. These predictions were used for fault detection, isolation of suspect material, and real-time troubleshooting during HME. Additionally, the NIR/PLS output was used for real-time release of the intermediate drug product.