Vibrational and UV-Visible spectroscopies

Raman spectroscopy is a vibrational spectroscopy (based on the physical phenomenon of diffusion) that provides complementary information to infrared spectroscopy (absorption spectroscopy).

This equipment is dedicated to the identification of species present in many organic or inorganic materials (on the 'surface' of a catalyst, on plates, powders, bulk compounds, liquids, etc.). One of the advantages of using Raman to study certain materials is that the presence of water does not interfere with the Raman signal (water scattering is very low). This technique is therefore very effective for characterizing aqueous solutions, supported catalysts, etc.

This spectrometer is equipped with 2 laser sources (532 nm: green and 785 nm: red), 4 gratings (600 to 2400 lines / mm), which allows the spectra recording conditions to be optimized according to the user's needs in a range of wave numbers from 100 to 4000 cm^-1.

This spectrometer is mainly used in micro-Raman mode. It is equipped with an optical microscope that can be used to select (and characterize) if necessary several zones on the sample (for example to check its homogeneity…). This microscope can also be used to zoom in on a particular area, so that the laser beam can be focused more or less on the sample (and the laser power received by the sample can be adjusted to optimize signal intensity). By focusing the laser beam strongly and increasing the laser power, it is even possible to locally simulate the temperature behavior (calcination) of certain samples, which can rise sharply on a micrometric scale. For samples that are unstable at high temperatures, it is possible to significantly reduce the laser power (either by adding filters to the incident laser path, or by defocusing the beam).

A motorized xy-z stage can be used to map samples.

The spectrometer is also coupled to an optical fiber and a probe for in-situ immersion (or contact) measurements in liquid media (corrosive or not).

Finally, the instrument can be connected to a Mantis Harrick Prying Cell for in-situ studies (catalytic, etc.).

Raman Spectrometer Horiba Labram HR800 – Université d’Artois, Lens

This spectrometer is a high-resolution Raman, thanks to its 80 cm focal length and 1,800-line grating (resolution of the order of 0.3 cm-1). However, it can be used in low-resolution mode if required (equipped with a 2nd dispersion grating). It operates in micro-Raman mode (with an optical microscope) and is fitted with a motorized stage (removable), enabling mapping.

This spectrometer is Horiba's "research" model. The optical part is accessible and customizable, so it can be easily adapted if required (addition of lasers, filters, polarizers, half-wave plate, etc.). It can also be configured to work in the UV and/or near-IR range.

The downside of this modularity is that this spectrometer is a little less user-friendly than the XPlora for the occasional user. Another price to pay for this adaptability and resolution is brightness. In general, the HR is less sensitive than the XPlora.

Sample preparation is carried out on site. On request, results can be interpreted in collaboration with the applicant.

UV-Visible spectroscopy is an absorption spectroscopy involving electronic transitions. It can be used to identify species present in many organic or inorganic materials (catalysts, plates, powders, bulk compounds, liquids, etc.) and also to quantify these species (mainly for liquids). This spectroscopy is particularly suitable for identifying metal complexes.

The platform is equipped with 2 UV-Visible spectrometers:

UV-Visible Spectrometer Perkin Elmer Lambda 650 (cité scientifique, Villeneuve d’Ascq)

UV-Visible Spectrometer Shimadzu UV-2600 (Université d’Artois, Lens)

Both spectrometers are equipped with a permanent (Lambda 650) or removable (UV-2600) integrating sphere, enabling easy characterization of liquids (by transmission) and solids (by diffuse reflection) in the wavelength range 200 - 900 nm (Lambda 650) or 220-1400 nm (UV-2600).