Column: Molecular Spectroscopy Workbench

March 01, 2020

Raman imaging provides detailed crystal orientation information for twodimensional MoS2 prepared by chemical vapor deposition on silicon substrates. These two-dimensional crystals consist of individual atomic layers of sulfur, molybdenum, and sulfur atoms.

February 01, 2020

Raman microscopy, combined with X-ray fluorescence, can provide detailed information about extractables and leachables from medically implantable devices.

December 01, 2019

Raman measurements can be used to infer the temperature of a material based on the Stokes and anti-Stokes band signal strengths, and by applying a predefined mathematical relationship. In reality, the temperature, Raman shift, and laser excitation wavelength all interact, and should be considered to better understand these measurements.

November 01, 2019

Raman 2D-COS spectral data provide information on conformational changes of polymers. Here, Raman spectra of ethylene vinyl acetate and vinyl acetate copolymer are measured and interpreted, enabling a description of morphological changes related to the vinyl acetate group.

September 01, 2019

When stress is applied to an object, it can produce strain. Strain can be detected through changes in peak position and bandwidth in Raman spectra. Here, we show examples of how strain in technologically impor tant materials appears in the Raman spectra.

June 01, 2019

The spectral behavior of water is studied using Raman with an NIR spectrograph and dual wavelength lasers for measurements of both the fingerprint and the OH stretching regions. Raman spectra are recorded between 5 ⁰C and 80 ⁰C, and treated with both band-fitting and the 2D-COS algorithm revealing improved insights into the spectral behavior of water.

March 01, 2019

The differentiation of polymorphs is important, particularly in the pharmaceutical industry. We demonstrate the practicality of using Raman spectroscopy to differentiate crystal forms for polymorph characterization and screening, and explain aspects of chemical bonding and solid state structure that affect the Raman spectra of crystal lattice vibrational modes.

February 01, 2019

Two-dimensional correlation spectroscopy (2D-COS) can reveal subtle chemical interactions that are difficult to discern when analyzing individual spectra. A demonstration of the subtleties of this technique can be seen in the analysis of ethanol–water and ethanol–methanol mixtures.

December 01, 2018

Resonance Raman spectroscopy demonstrates up to 106 signal enhancement. In this overview a detailed description of how resonance Raman spectroscopy differs from normal Raman spectroscopy is given with some specific examples explained.

November 01, 2018

Spectral changes revealed by two-dimensional correlation spectroscopy can be used to interpret structural changes in polymers determined by processing conditions, so that materials can be rationally engineered for particular applications with known mechanical requirements.