Spectroscopy-09-01-2015

Raman bands in the low energy region of the spectrum of crystals are attributed to so-called external lattice vibrational modes. The Raman bands from these external vibrational modes (low energy phonons) are very sensitive to crystal structure and orientation with respect to the incident laser polarization and to molecular interactions within the crystal. The low energy vibrational modes of many organic molecular crystals have very high Raman scattering cross-sections. Raman spectra and images of low energy phonons in so-called two dimensional (2D) crystals such as few-layer MoS2 reveal spatial variations in the solid state structure that are not evident in the higher energy bands.

Raman spectroscopy is applied to quality control of agricultural products with greater frequency, and can also be used to refine regulatory criteria for both agricultural and environmental monitoring. It is now integrated into everything from hand held SERS detectors to unmanned aerial vehicles to monitor the gamut from genetic variation to soil and water content. Development opportunities, particularly with bundled technologies, continue to emerge as demand for quality assurance increases.

A proposed update to USP on Analytical Instrument Qualification (AIQ) has been issued for public comment. Here, we identify the changes that are proposed and their impact on the AIQ process of analytical instruments and laboratory computerized systems.

Identity testing is used in the pharmaceutical, food, and dietary supplement industries (amongst others) to ensure raw materials and final products have the correct chemical composition by answering the spectral question: Are these two samples the same? The first part of this installment instructs readers on the correct way to perform identity testing. The interpretation portion of the installment wraps up our discussion of straight chain alkanes by discussing how to determine chain length from infrared spectra. We also go over the answer to the problem from the last installment.

Letter to the editor regarding 30 Years of Spectroscopy, “Analysis of the State of the Art: IR Spectroscopy,” Volume 30, Number 6, June 2015

Click the title above to open the Spectroscopy September 2015 regular issue, Vol 30 No 9, in an interactive PDF format.