Column: Molecular Spectroscopy Workbench

Articles

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.

Effect of Layer Number and Crystal Stacking Orientation on the Raman Spectra of Two-Dimensional MoS2

Fran Adar is the Worldwide Raman Applications manager for Horiba Jobin Yvon.

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

Use of Raman Microscopy to Characterize Extractables and Leachables

David Tuschel is a Raman applications manager at Horiba Scientific in Edison, New Jersey, where he works with Fran Adar. David is sharing authorship of the "Molecular Spectroscopy Workbench" column with Fran.

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.

Raman Thermometry: Understanding the Mathematics to Better Design Raman Measurements

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.

Raman Analysis of Ethylene Vinyl Acetate Copolymers–Using 2D-COS for Identifying Structural Changes

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.

Stress, Strain, and Raman Spectroscopy

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.

Measurement of the Temperature Dependence of Water Using a Near-Infrared Raman Spectrograph

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.

Raman Spectroscopy and Polymorphism

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.

Use of Raman Spectroscopy and 2D-COS for the Detection and Characterization of Chemical Interactions

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.

Exploring Resonance Raman Spectroscopy

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.