The Raman effect is observed when monochromatic light couples with molecular rotovibrational or crystal vibrational excitations in the sample under investigation. Some of the photons transfer a tiny amount of energy to the oscillating atoms, and the color of the scattered light is slightly redshifted. Although this effect was first observed by naked eye by sir C.V. Raman in 1928, is indeed very elusive. However, today, with the advent of highly monochromatic and high power laser sources and high resolution spectrometers, it gained a widespread diffusion for a large range of applications. Since the roto-vibrational information is specific to the chemical bonds and the symmetry of the molecules or of the crystal, the Raman spectrum provides a fingerprint by which the sample can be characterized with an incredible precision.
The outstanding properties of Raman spectroscopy came to a price: usually Raman signal is disarmingly low. To circumvent this issue, strategies based on the plasmonic enhancement of the local electromagnetic field were proposed: with SERS (Surface Enhanced Raman Spectroscopy) amplification of the Raman signal up to 1014 times were shown; with TERS (Tip Enhanced Raman Scattering) spatial resolution down to 7nm was obtained. Choosing an excitation wavelength corresponding to an electric transition in the sample, Resonant Raman (SERRS) can be performed with a further enhancement in signal.
Operando Raman spectroscopy allows combining the powerful non-destructive chemical characterization capabilities of Raman spectroscopy with electrochemical evaluation. In this way, the evolution of the samples can be measured while applying electrochemical stimulus. A range of operando chambers is accessible to IREC, including electrochemical chambers (tight liquid chamber with reference electrodes) and high temperature stages.
Chemical composition determination, crystalline structure characterisation, strain calculation, non-destructive fast measurements on liquids or solids
Multiple laser sources with optical power at the sample between 0.1 and 10 mW are focused on the sample using a confocal microscope
Available laser lines: 363, 488, 514 and 647 nm
Visible CCD detector: 220-800 nm
Spatial resolution between 0.5 and 2 µm depending on the chosen microscope objective
Best spectral resolution 0.1cm-1
XY mapping stage range: 100 mm x 100 mm
XY mapping stage resolution: 0.1 µm
From few mm2 to 12” diameter flat samples
CNR-IOM (PG)
Italy
micro-Raman Spectrometer
Laser 532 nm
CCD camera
500x500 um
Degree of freedom (x, y, z) range and resolution (1 um)
30-4000 cm-1
10 cm-1
JRC - ISPRA
Italy
Confocal Raman Microscope
The CRM is a confocal optical microscope equipped with an automatic XYZ stage, that is able to collect the Raman spectrum at each position of the stage. It returns a hyperspectral image, namely a Raman spectrum for each XYZ point in the space. The Raman spectrum is a fingerprint of the molecular structures. The CRM enable to generate chemical tomography of the sample
EURONANOLAB
France
RS at EURONANOLAB - CEITEC
EURONANOLAB
France
RS at EURONANOLAB - MMI
na
na
no
no
na
0
EURONANOLAB
France
RS at EURONANOLAB - IMT
CSIC-ICMAB
Spain
RS at CSIC-ICMAB
Vibrational spectroscopy. Chemical composition determination, crystalline structure characterization, strain determination, non-destructive fast measurements on solids.
Horiba LabRam HR800 grating spectrometer with 800 mm focal length with two gratings (1800 lines/mm and 600 lines/mm) and coupled to confocal microscope.
Multiple laser sources with optical power at the sample between 0.1 and 10 mW are focused on the sample using a confocal microscope (available long working-distance objectives with x20, x50 and x100 magnification).
Available laser lines: 473, 488, 514, 633 and 785 nm for Raman and 355 and 405 nm also for photoluminescence (PL).
Spatial resolution between 1 and 2 µm depending on the chosen microscope objective. Best spectral resolution of 1 or 0.1 cm-1, depending on the grating in use.
XY motorized stage range: 100 mm x 100 mm XY mapping stage resolution: 0.1 µm. Mappings NOT possible though.
From few mm2 to 4” diameter samples. Working distances of the microscope objectives between 3 – 25 mm.
Low-temperature measurements (80 – 350 K) with gas-flow cryostat are possible but only after well-justified request.
In SEM a beam is scanned over a sample surface while a signal from secondary or back-scattered electrons is recorded. SEM is used to image an area of the sample with nanometric resolution, and also to measure its composition, crystallographic phase distribution and local texture.
XRD provides non-destructive information on the structural order of a material. At large scattering angles XRD permits to identify different crystal phases and to quantify lattice distances and crystalline volume fractions. At low angles of incidence the surface roughness of a single crystal and the thickness of a deposition layer can be obtained.
XPS is a surface spectroscopic technique for quantitative measurements of the elemental composition or stoichiometry and the chemical state of the present elements, like their oxidation state and chemical bonds. XPS is highly surface sensitive, giving chemical and binding energy information from the a narrow region close to the surface.
In TEM/Scanning TEM (STEM) high energy electrons incident on ultra-thin samples, allow imaging, diffraction, electron energy loss spectroscopy and chemical analysis of solid materials with a spatial resolution on the order of 1-2 Å. Samples must have a thickness of a few tens of nanometres and are prepared in sample preparation laboratory.
AFM is a surface sensitive technique permitting to obtain a microscopic image of the topography of a material surface and certain properties (like friction force, magnetization properties…). Typical lateral image sizes are within a range of only a few Nanometers to several Micrometers, and height changes of less than a Nanometer.
