(update February 24th 2023

Person in charge

Olivier CHAUVET - Etienne JANOD

Topic

EPR (Electronic Paramagnetic Resonance) is a spectroscopic technique that allows the detection of species with unpaired electrons, via their magnetic signature.These species present in solid or liquid materials can be free radicals in molecular or biological materials, paramagnetic ions of transition metals such as Cu(II), Mn(II), V(IV), Fe(III),Cr(III), Cr(V), Co(II), Rh(II), Ni(I), Mo(V) or Ti(III), paramagnetic defects, spins of conduction electrons… .This technique allows obtaining chemical information (nature and environment of the paramagnetic species).It can also provide insight into the physical or physico-chemical properties of compounds: electronic properties of conductors or insulators, magnetic properties, redox properties, etc.

Equipments

Electron Spin Resonance (continuous wave, Bruker Elexsys E 500)

Performances

• • • samples :
      -Type: powder, crystal, gel, thick films, mass between a few tens of µg and a few tens of mg,
      - dimensions : the sample should fit into a tube of about 2-3 mm inside diameter
    • available cavities:
      - X-Band: resonance field around 3350 G for g = 2
      - Q-Band: resonance field around 12500 G pour g = 2
    • Sensitivity: under the most favorable conditions, detection threshold close to one part per billion (1 ppb),
    • Temperature range: :from 77 to 400K (liquid nitrogen cryostat)
    • Possibilities (tuning required) to make measurements under light irradiation, in an electrochemical cell, under electrical bias,...
      

Application examples

The applications of EPR cover many fields of scientific research, in chemistry, physics, materials science, biology and medicine.Among the recent examples obtained on the IMN spectrometer, we can note measurements aimed at characterizing defects induced by irradiation in materials used in the field of health.

Learn more:

Links towards Bruker E500 user manual

(update February 28th 2023)

Person in charge
Pierre-Emmanuel PETIT

Thomas FOURNIER
Jonathan HAMON

X-ray diffraction (XRD) is an elastic scattering technique, i.e. without loss of photon energy (unchanged wavelength), which gives rise to interferences. A distinction is made between single crystal and powder diffraction techniques. XRD is also a powerful technique to characterize thin films.

Applications

Single crystals (four-circle goniometer in Kappa geometry):

• crystal structures
• Low and moderate temperature phase transitions (for temperaturesranging from 90K to 500K)

Powders (Bragg-Brentano or Debye-Scherrer geometries):

• identification of crystallized phases
• quantitative determination of crystalline (possibly /
• determination
• crystallite size / microstrain (studies based on diffraction peak
• phase transitions at high temperatures / kinetics of these transitions
• operando studies (electrochemistry)
• characterization of the local of amorphous or poorly crystallizedmaterials (PDF studies)

Thin films (Bragg-Brentano geometry, grazing incidence diffraction or “ω-scan”):

• identification of crystalline phases
• microstructure
• texture (minimalist version: usea “rocking curve” type scan, alsocalled “omega-scan”)

The fleet consists of 8 machines,themost recentones being,on the whole, more versatilethan the older ones, which remain in a more specialized use:

Single crystal diffractometers:

• Rigaku Synergy S
• Nonius KappaCCD

Powder and Thin Film Diffractometers:

• Bruker D8 A25 “Da Vinci”
• PanalyticalX'Pert pro
• 2 Bruker D8 Series II: “Sample Changer” and “Chamber”
• Siemens D5000
• INEL XRG3500

Diffractometers for single crystals:

These two devices, housed at the Lombarderie site of IMN, are also used by CEISAM, and are accessible from outside under certain conditions.

Rigaku Synergy S Diffractometer

This apparatus, installed at IMN in 2020, is equipped with a microsource tube with a Mo anode (with its Montel-type focusing optics), a Hypix6000 hybrid pixel Si detector and a nitrogen cryogenic system (Oxford Cryosystems 800+) that allows the temperature of the crystal to be varied from 90 K to 500 K. It combines the advantages of a microsource (high diffracted intensity with small crystals) with the excellent signal-to-noise ratio provided by a latest- generation hybrid pixel Si detector.

The cost of the diffractometer (300 k€) was financed by:

Nonius KappaCCD Diffractometer

This apparatus, installed at the IMN in 2002, is equipped with a "classic" Mo anode X-ray tube, a "Princeton" CCD detector and a nitrogen cryogenic system (Oxford Cryosystem 700), allowing to reach the temperature range 90 K-373 K. The now outdated characteristics of its detector (notably its high readout noise) make it a second choice device. Nevertheless, it has been maintained for the time being and is fully functional.

Diffractometers for powders and thin films:

Bruker D8 A25 « Da Vinci » Diffractometer

Equipped with a second-generation Cu anode tube Si detector ("LynxEye XE") and numerous accessories (motorized slit, multilayer parabolic mirror, motorized XYZ table...), this θ/θ geometry device is very versatile (manufactured in 2013 and installed at the IMN site Lombarderie in 2020) and allows many applications:

• the energy resolution of the detector allows to avoid the X-ray fluorescence of samples containing Fe or Co, whatever the acquisition geometry used (Bragg-Brentano, parallel beam...);
• sits multi-layer mirror and radial Soller slits make it possible to study with a parallel beam massive samples that are not very regular and that one does not wish to polish or grind (non-destructive analysis). It is possible to envisage a fairly coarse spatial resolution (of the order of a millimeter);
• the multi-layer mirror, radial Soller slits and motorized table allow for grazing incidence studies of thin film samples;
• it is also possible to perform X-ray reflectometry using the motorized table, the multilayer mirror and appropriate slits;
• a stand to install electrochemical cells for operando studies.

Panalytical X’Pert pro Diffractometer

This apparatus, installed in 2009 at the IMN Chantrerie site, is also versatile, and is equipped with a first-generation Si strip detector ("X’Celerator"), whose energy resolution does not allow for the efficient removal of fluorescence radiation from Fe or Co. The speed of acquisition allowed by this detector allows in most cases to acquire excellent quality patterns in Bragg-Brentano (θ/θ) mode:

• a sample changer allowsthe acquisitiondiagrams ofa largenumber of powdered ormassive samples of small volume;
• a suitable sample holder allows the study of larger volume bulk samples and the accommodation of electrochemical cells (operando studies);
• an Anton Paar HTK1200N furnace for high temperature studies (T<1200°C, in air or neutral atmosphere).

Solid specimens of any size should have a flat surface (rough polishing may be sufficient). Otherwise, the use of the D8 "Da Vinci" described above should be considered.

Bruker D8 Série II Diffractometer « sample changer »

This apparatus, installed in 2006 at the IMN Lombarderie site, is equipped with a Cu anode tube and a first generation 1-D Si strip detector ("LynxEye"). It is also equipped with a Ge monochromator (111) placed at the exit of the tube stand, which makes it possible to obtain pure Cu K1 radiation. The Ge monochromator has advantages for powders with large crystallographic unit cells and/or low symmetry, as well as for Bragg-Brentano (θ/2θ) mode studies of thin-film samples deposited on single-crystal substrates.

This apparatus, not very versatile but equipped with a 90-position sample changer, is specialized in the acquisition in Bragg-Brentano mode of powder or massive but small samples, or samples deposited in thin layers on a monocrystalline or amorphous substrate. Its detector offers excellent performance except for samples containing Fe or Co, whose X-ray fluorescence is poorly filtered by the detector. It is also possible to install an airtight cell. This apparatus, the most used of the X-ray equipment, is often close to saturation, and allows the acquisition of about 2300-3000 patterns per year. It is widely open to external users, and several laboratories in Nantes (CEISAM, LPG, Arc’Antique, Université Gustave Eiffel Nantes) use it regularly.

Bruker D8 « chamber » Diffractometer with Anton Paar HTK 1200N furnace

This instrument, installed in 2006 at IMN (Lombarderie site), is equipped with a Cu or Mo anode tube, a motorized divergence slit and a fast 1-D gas detector ("Vantec"). The acquisition geometry is Bragg-Brentano θ/θ.

It works by campaigns and allows to install:

• a Cu anode tube and the Anton Paar HTK1200 N high temperature chamber (T<1200 °C, exclusively under air or neutral gas)
• a Cu anode tube and the Anton Paar XRK 900 high-temperature chamber (T<900 °C, reducing and/or humid atmosphere, vacuum - see the photograph of this instrument and more details on these chambers);
• an adapter support for electrolytic cells (operando studies);a Mo tube for PDF acquisition campaigns in Bragg-Brentano mode. This type of study, also known as total scattering, allows to investigate the local order of amorphous or poorly crystallized compounds.

Siemens D5000 Diffractometer

This apparatus, in Bragg-Brentano θ/θ geometry, is equipped with a Cu anode tube, a point detector (a scintillator) and a graphite secondary monochromator.

Advantages: easy access - no limitation for minimum angle (large unit cells) - filters X-ray fluorescence (samples containing Fe or Co).

Disadvantages: relatively long acquisition time (1 night). Presence of Cu Kα2 radiation - Despite these disadvantages, this device is still used (mainly because of its easy access), and is kept operational.

INEL XRG3500 Diffractometer

This instrument is dedicated to capillary diffraction in Debye-Scherrer geometry. It is equipped with a Cu anode tube, a primary monochromator (quartz) and a position-sensitive gas detector, allowing simultaneous acquisition over a 120° angular range.

Advantages: small quantities - air sensitive samples - relatively small minimum angle - no Kα2 radiation - relatively fast acquisition.

Disadvantages: absorbent and/or fluorescent samples. As it is the only apparatus in the laboratory that allows the use of capillaries, it remains indispensable despite its great age (apparatus installed in 1988).

Anton Paar XRK900 Chamber

Ancillary equipment for powder diffractometers:

• High temperature chambers :

  Two Anton Paar HTK1200 N chambers (T < 1200 °C, neutral atmosphere or under air), installed part-time respectively on the Bruker D8 “Oven” (Lombardy site) and the Panalytical X’pert pro (La Chantrerie site). These chambers do not allow for working under humid air.

  An Anton Paar XRK 900 chamber (T < 900°C), installed (alternately) on the Bruker D8 “oven”. This chamber is complementary to the other chambers, as it allows work to be carried out in a reducing atmosphere (a 5% H2/N2 mixture) and/or in a humid atmosphere.

• Sealed cells for air sensitive samples. Can be used on the Bruker D8 “Autosampler” and Bruker D8 “Da Vinci”.

• Electrochemical cells adaptable on the Panalytical X’pert Pro (at La Chantrerie) and on the Bruker D8 “Oven” and D8 “Da Vinci”. Not accessible outside IMN.

Technical manager

Eric GAUTRON

Nicolas GAUTIER
Amina MERABET

Scientist Director

Philippe MOREAU

The equipment and activities described on this page are part of the GIS "CIMEN" which is currently under construction. It can be found on the website https://www.gis-cimen.fr/

Equipments

1- Nant'Themis (S/TEM Themis Z G3 from Thermo Fisher Scientific)

This new generation microscope was installed in 2018. Its exceptional configuration (monochromator, probe corrector, energy filter with direct detection camera) was the first to be installed in Europe. Having been defined to be open and interdisciplinary, the Nant'Themis is available to :

• IMN researchers,
• Nantes laboratories
• regional and national laboratories,
• industries working in fields such as metallurgy, biology, energy...

The Nant'Themis microscope was funded by the « 2015-2020 Contrat de Plan Etat Région (CPER)

The cost of the microscope (>3.5M€) was supported by

• • • ETAT 18%
    • FEDER (Europe) 50%
    • REGION Pays de la Loire 14%
    • Nantes Métropole 14%
    • CNRS 4%

The CNRS DR17 Regional Delegation financed a large part of the developpement work to fit out the MET room and the external accesses. The inauguration took place on 7 February 2019.

Nant'Themis is equipped with a Schottky X-FEG gun (high brightness and high stability), a monochromator (achievable energy resolution < 100 meV) and a probe corrector (resolution : 60 pm @ 300 kV in STEM). It is aligned at accelerating voltages of 300, 200 and 80 kV chosen according to the sample and the techniques used to characterise it.

In addition to "classical" electron diffraction and imaging, other more recent techniques or those under development can be used. These include:

• Ultrafast image acquisition, in situ mode: up to 300 frames/s in 512*512 pixels with the Gatan OneView IS camera

• Diffraction imaging in STEM mode (Gatan STEMx)
  

Here are some examples of results obtained at IMN :

HAADF image of a hexagonal perovskite Ba2.5Sr0.5NiSb2O9 along [010] and associated EDX maps of the elements Sb (green), Ni (blue) and Ba (yellow) (sample: IMN, C. Deudon, C. Payen, images: IMN, M. Caldes, N. Gautier, E. Gautron, July 18). One of the Sb sites has an occupancy factor of 50%, the other 100%. On the right, theoretical crystal structure and associated simulation (programme: Dr Probe, thickness 5.7 nm)	HAADF, iDPC and dDPC images of GaN along [11-20] (sample: Thermo Fisher Scientific, images: IMN, E. Gautron, Nov 18). The nitrogen atoms separated by 63 pm are clearly visible in dDPC. The contrast in iDPC is related to the projected potential, that in dDPC to the charge density in the sample (i = integrated, d = differentiated, DPC = Differential Phase Contrast)
Evolution de la morphologie de nanoparticules métalliques avec la température (Porte-objet NanoEx-i/v, images : IMN, E. Gautron, déc. 18).	Images MET en champ clair de précipités dans une matrice d’aluminium (échantillon : G. Doumenc, R. Gautier, L. Couturier, images : IMN, E. Gautron, déc. 18).
Cartographie d’orientations d’une couche de TiO2 anatase déposée par PECVD sur substrat SiO2/Si (échantillon : D. Li, M. Richard-Plouet, images : IMN, M. Richard-Plouet, N.Gautier, déc. 18). Nant'Themis was one of the first microscopes in Europe to be equipped with a configuration combining a very high resolution energy filter (Gatan GIF Quantum 966 ERS) with a direct electron detection camera (Gatan K2 Summit) in addition to the conventional CCD camera. This camera technology greatly improves both energy resolution and signal-to-noise ratio of electron energy loss spectra (EELS) compared to a CCD camera. It allows to characterise highly sensitive to the electron beam samples using EELS.   Lien vers http://www.gatan.com/products/tem-imaging-spectroscopy/gif-quantum-k2-system Seven different holders are available depending on the application: EDX analysis : single tilt (ST) (+-35°) and double tilt (DT) (+-35°, +-30°) Room or Cryo temperature tomography: ST (+-75°) et ST cryotransfert (+-80°) Characterization of air-sentitive samples: vaccum transfert or controled atmosphere DT (+-35°, +-30°) Heating (1200 °C max.) MEMS technology with possible polarisation « open cell » for operando studies : electrical probe (STM tip) and potentiostat/galvanostat module 2- H-9000 NAR (Hitachi)) This microscope has a 300 kV accelerating voltage and a small gap pole piece (0.18 nm point resolution) It is equipped with a double-tilt (+-15°) specimen holder to orientate the crystals before acquiring high-resolution micrographs (TEM only) or to obtain electron diffraction patterns in zone axis. A Si(Li) EDX detector allows semi-quantitative elemental analysis. Image MET (à gauche) d’une interface entre une couche de MoSe2 et une couche de Cu(In,Ga)Se2 (cellule PV en couches minces) A droite, modèle atomique associé  (éch.: IMN, image : E. Gautron) 3- Autres équipements de préparation des échantillons The electron microscopy department is equipped with several preparation devices, used according to the nature and morphology of the samples but also to the type of characterisation desired. . Faisceau d'ions focalisés (FIB)   Ultramicrotome, cryo-ultramicrotome : Leica UC7/FC7 Découpe de polymères, de métaux « mous », de matériaux biologiques à l’aide de couteaux en diamant Découpe à froid (LN2) de polymères dont Tg < Tamb Amincisseur ionique : PIPS 691 Gatan Système de polissage par faisceaux d’ions Ar+ Platine froide (LN2) et basse tension permettant de minimiser les artefacts Amincissement mécanique : Disc Grinder, Polisseuses, tripode, T-tool, Dimpler Grinder Fischione Polissage électrolytique : Struers TenuPol-5

(update February 28th  2023)

Person in charge

Florian MASSUYEAU

Principle :

Based on the luminescence of a sample, this technique detects precisely its temporal evolution according to an ultrafast excitation.

It brings information on excited states, its radiative transitions but also its non-radiative transitions. Luminescence decays reveal the dynamic of the photogenerated species: lifetime, excitonic migration, mechanism of charge/energy transfer, bimolecular interaction (e.g. exciton-exciton annihilation).

Different strategies have been proposed to temporally resolve the photoluminescence signature. At IMN, the setup use a streak camera to obtain 3-dimensionnal images (time, wavelength and PL intensity).
Every kind of samples can be observed: solution, powder, thin film, gemstone.

3D-image obtained on a PPV thin film (time window: 1 ns or 1000 ps). The fluorescence intensity is based on a color scale from blue (minimum) to red (maximum). The CCD record the spectrum on a 300 nm range. Excitation : 400 nm.

Equipments :

The home-made setup record 3D images in the UV-Vis range (from 270 to 800 nm) and in a temporal range from 1ns to 1ms. Non-temporally-resolved measurements are recorded thanks to an IRCCD InGaAs from (800-1700 nm). This setup is basically divided in two parts: the pulsed excitation to generate the transient photoluminescence signature and the detection to collect this signal.

Scheme of the home-made time-resolved photoluminescence setup at IMN.

Pictures of the setup at IMN

- Excitation part

• • Femtosecond laser, 1 kHz, Hurricane X Spectra-Physics (pulse duration: 100 fs, 800nm, 1W) ;
  • OPA and SHG/THG Spectra-Physics.
    
     
     

- Detection part

• • SDG II Spectra physics, delay generator for the 0.5 ns-100 ns range;
  • DG535 Stanford Research Systems, delay generator for the 100 ns-1 ms range ;
  • Acton Princeton Instrument SP 2360 spectrometer ;
  • CCD NIR Princeton Instrument OMA V ;
  • Streak camera Hamamatsu C7700 (5 ps resolution) coupled with a CCD camera ORCA II (1344x1024 pixels) cooled down to -60°C.

Left: excitation part , right: detection part.

Examples :

 Temperature-resolved lifetime evolution for two compounds: (TDMP)PbBr₄ and (BAPP)Pb₂Br₈

Time-resolved PL on [C₆H₁₆N₂]₃[Cu₄Br₆][Cu₂Br₆].
(a) Streak camera images obtained for two temporal windows.
(b) and (c) Decays integrated on red and green rectangles, monoexponential behavior.
(Scientific Reports, 2017, 7, 45537).

Temporal behaviour differences for CdSe quantum dots emissions in solution or thin film.
(Applied Physics Letters, 2010, 97, 153111).

(update February 28th 2023)

Person in charge

Stéphane GROLLEAU - Hélène TERRISSE

Equipment

• • • Laser Granulomètry :

Malvern  Mastersizer 3000, with an ultrasonic tank in situ, also equipped with a dry powder disperser.
Size range: 20 nm to 1 mm.
Characterization of the size distribution of particles in liquids (syrups, emulsions, suspensions…) and of dry powders.

• • • Dynamic Light Scattering (DLS):

Malvern Zetasizer NanoZS.

Analysis at two angles (13° et 173°) of the size of particles and molecules.

Technology NIBS enabling to better detect aggregates, and to measure small or dilute samples, as well as highly concentrated samples.

Size range: 1 nm to 10 µm.

Incident wavelength: 633 nm.

Volume of cuvettes (polystyrene or quartz): 1 mL.

Temperature range: 10-90°C.
Algorithms for the autocorrelation function analysis: Cumulants, Contin, NNLS.

Possibility to perform static light scattering analyses with Debye model (molecular weight determination).

Operating principle:

- Laser granulometry:

Granulometry through diffraction and light scattering enables the determination of particles diameter between 20 nm and 1 mm, in suspension in a liquid, or as dry powder (dispersion of particles with compressed air). A laser beam illuminates the particles, which scatter light all around them, with scattering patterns specific to their size. The intensity of scattered light is recorded in a range of angles between 0 and 30°, and after mathematical analysis (MIE equations, which require the knowledge of refractive index of the particles and the dispersion medium), the software gives a histogram indicating the volume fraction of each granulometric class. This method determines the diameter of the sphere with the same volume as the particle.

- Dynamic Light Scattering: (DLS) :

Granulometry through quasi-elastic light scattering enables the measurement of particles with a diameter between 1 nm and a few µm, in suspension in a liquid. This method lies on the determination, by light scattering, of the velocity of colloidal particles when they are subjected to Brownian motion. The instrument records, according to time, the fluctuations of the light scattered by moving particles. This signal is then mathematically analysed to create an autocorrelation function, which enables determination of the translational diffusion coefficient of the particles. The latter is directly proportional to their size through Stokes-Einstein relation. This technique leads to the hydrodynamic diameter of particles, which takes into account the solvation layer around the particles surface. The thickness of this layer depends on various parameters, such as the ionic strength of the dispersion medium.

Examples

• Granulometric distribution of food-grade titanium dioxide particles (E171) in various pH conditions, obtained through laser granulometry.

Oxy-gallates et oxy-germanates de terre rares conducteurs par ions oxygène, A. Chesnaud, Thèse de doctorat, Université de Nantes (2005).

• • Analysis by DLS of a colloidal suspension of TiDMF.4H₂O obtained by polycondensation of TiOCl₂ in DMF in the presence of water. Figure (a) presents the distribution in intensity of scattered light, figure (b) presents the same distribution, converted in volume fraction.

Monodispersed titanium oxide nanoparticles in N,N-dimethylformamide : water solutions,
H. Terrisse et al., Journal of Sol-Gel Science and Technology, volume 67, 288-296 (2013).

Technical Manager

Nicolas STEPHANT

Scientist Officer

Philippe MOREAU

The instruments and the activity described in this page take part in the GIS "CIMEN" in progress. It can be discovered on the website : https://www.gis-cimen.fr/

Equipment

A ZEISS Crossbeam 550L dual-beam (ions and electrons) scanning electron microscope (FIB) installed in late 2019.

• • Site Lombarderie (UFR Sciences)

The instrument is installed on the Science campus in the centre de microcaractérisation (CMC) building dedicated to scanning and transmission electron microscopy and atomic force microscopy (AFM).

The sample can be observed under conventional scanning electron microscopy using the electron beam generating column or milled with an ion beam using the second column of the microscope.

It allows to machine a sample by abrasion to extract a thin section for transmission electron microscopy. An in-situ nanomanipulator is provided to remove the thin section and fix it on a TEM grid. Two organometallic gas injectors allow to weld the sample, to contact it or to etch it by metal deposition (platinum or carbon).

It is also possible to mill a sample layer by layer while acquiring images each time. These images are then processed by software to restore the 3D volume destroyed by the beam and quantify different parameters about the observed phases.

The apparatus is equipped with an Oxford EDS detector for the analysis of chemical elements and an EBSD detector to characterize the crystalline orientations. Both techniques are usable in combination with a 3D acquisition.

A cryofreezing system allows to work at very low temperature on samples which are sensitive under the beam (Quorum). It includes a cold transfer system between the microscope and a glove box under controlled atmosphere.

The microscope is also coupled to a Raman spectrometer (Renishaw).

An uncooled vacuum transfer system is provided between a glove box and the microscope.

The FIB is accessible to external users.

Extraction of a TEM lamella

To work on a solid material in transmission electron microscopy, it must be thin enough so that the electron beam can pass through it and so that the information transmitted is not compromised by the thickness of the observed area. Before the advent of the FIB, this was a tricky job performed by mechanical or chemical methods or by exposure to an ion beam. These methods are very rough to achieve a correct thickness, and especially to target a very precise area in a block that is observed with the naked eye or by optical instruments. The precision of FIB milling now makes it possible to extract a TEM lamella of a hundred nanometers thick in a solid sample. The location from which it is extracted is located on the sample with electronic imaging, which allows the lamella to be removed from the exact location that we intend to analyze with precision.

In a first step, a thick slide is carved out of the material. It is then welded on a nanomanipulator by organometallic deposition under ion beam (platinum) then moved and welded on a copper grid compatible with the TEM sample holder. The final refinement is then performed with the ion beam.

Observation of a sample section

In most abrasion operations, the surface of the sample is perpendicular to the ion beam and tilted at 54° to the electron beam. This disposition allows to observe with the electron column the face of an excavation made by the ion beam, as far as the observation is not obstructed by the opposite face. By choosing the shape of the hole to clear the perspective for the electron column (a cavity that can be compared to that of a ramp to access an underground parking), a cross-section in the depth of the sample can be observed. This is done exactly where it is needed and without any prior preparation of the sample, which should have been cut and polished before being introduced into the instrument if it had not been provided with an ion column.

3D Reconstruction

The abrasion capacity of the ion beam is controlled precisely enough to remove a very thin layer of material (theoretically down to about ten nanometers). If this operation is repeated a lot of times on the same surface, a volume of the sample is explored whose depth is proportional to the number of layers removed. If an electronic image of the surface is taken each time a layer is removed, we obtain a collection of images which, stacked one on top of the other, reflect the internal morphology of the volume that has been milled by successive layers.

It remains to process this collection of images with a software dedicated to 3D reconstruction to obtain an in-volume visualization of the sample. Several image analysis type treatments are available on the software to extract numerical data (for example porosity or volume occupied by a phase) and obtain a graphical representation.

3D acquisition on a filtration cell by Hélène Roberge

in the context of the e-BRIDGE project (NExT junior talent program).

Observation and cold milling

Some materials are either degraded by the beam or degraded by the vacuum in the column of the scanning microscopes. These are mainly samples containing water but also so-called "fragile" materials.

The dual beam microscope is equipped to observe these materials at cold temperature with a QUORUM system that allows to freeze a sample in liquid nitrogen before introducing it into a preparation chamber connected to the microscope by an airlock. A nitrogen gas circulation system cooled in a liquid nitrogen dewar allows to maintain the sample at -140° in this one under the protection of a trap cooled at -170° (to trap the residual contaminants). This chamber is provided with knives to fracture the sample then metalize it after a possible sublimation.

The sample is then introduced into the microscope for observation on a holder cooled in the same way as in the preparation chamber and similarly protected by a cold trap.

The freezing prior to all this can be done under vacuum in slashed nitrogen.

This device opens the way to the observation of samples that are not observable otherwise.

The FIB was funded by the 2015-2020 Plan Etat-Region Contract (CPER).The cost of the microscope (1.5M€) was funded by :

ETAT 18%
FEDER (Europe) 50%
REGION PAYS DE LA LOIRE 14%
NANTES METROPOLE 14%
CNRS 4%

(update March 01 st 2023)

Technical Managers

Nicolas STEPHANT

Thomas FOURNIER

Scientist Officer

Philippe MOREAU

The scanning electron microscope (SEM) replaces optical microscopy to make images when this one is no longer able to make images of sufficient resolution. It is the device used by the largest number of researchers at IMN to obtain images of the materials they manufacture. These images can be made on areas enlarged up to 1,000,000 times with a resolution of about one nanometer. The SEM is also very useful for the peripheral techniques that can be attached to it such as energy dispersive spectroscopy (EDS) which provides information on the chemical elements present in the sample and their respective masses..

The instruments and the activity described in this page take part in the GIS "CIMEN" in progress. It can be discovered on the website : https://www.gis-cimen.fr/

Equipments

The IMN's scanning electron microscopy facility is built around four machines located on two sites, "Lombardie" and "Chantrerie".

• • Site Lombarderie (UFR Sciences)

On the Science campus, the microscopes are located in the "Centre de Microcaractérisation" (CMC) building dedicated to scanning and transmission electron microscopy and atomic force microscopy (AFM).

Two instruments are available:

A JEOL JSM 7600F scanning microscope dedicated to high resolution imaging made available by its Shottky field emission gun and its in-lens electrons detectors. It is also equipped with a BRUKER SDD energy dispersive spectrometer to qualify chemical elements and perform spectral mapping.

 A JEOL JSM 5800LV scanning microscope with integrated energy dispersive spectrometer SDD SAMx. This instrument is mainly dedicated to quantitative chemical analysis but also to any chemical analysis work (X-ray mapping, concentration profiles, semi-quantitative analysis) and to routine imaging. A specific detector acquires images in cathodoluminescence. This microscope is also able to work in " low vacuum " mode.

These two instruments are widely accessible to external users within the context of the "service commun de microscopie électronique à balayage" of the University of Nantes, which owns the instruments.

Three carbon, platinum and gold/palladium metal coaters complete this equipment as well as a critical point dryer. The service also uses the sample preparation possibilities offered by the TEM service ( embedding, polishing, microtomy...) and also has a JEOL Cross Section Polisher to perform ion polishing on samples.

JEOL Cross Section Polisher

• • Site Chantrerie (Polytech'Nantes)

At Chantrerie, the microscopes are located in the ETMPA building, dedicated to research, and in the "ISITEM" building, dedicated to teaching, in the practicum corridor.

Two microscopes are available:

• A Zeiss Leo 1450VP microscope (2003) provided with a tungsten filament gun and mainly used for routine images and analysis. It is built with a SE, BSE retractable detector and an 80 mm2 EDS spectrometer from Oxford Instrument. Its low vacuum pumping mode allows the observation of insulating samples without coating them as well as vacuum sensitive or hydrated samples.

• A Zeiss Merlin microscope (2009) provided with a field emission gun used for precision analysis and high resolution images. It is provided with a SE and BSE detector in the chamber and a SE and BSE detector in the lens. It is equipped with a 50 mm2 Oxford EDS spectrometer, a WDS probe and an EBSD camera. It is also possible to mount a heated tensile stage for "in-situ" experiments.

As well as various sample preparation devices:

Quorum Q150R OR/Palladium ou Carbone sputter coater

(updated 2022, June 28th)

Person in charge

Benoit ANGLERAUD

Typical measurements :

• • • Height measurements by mechanical scanning of a tipped-stylus on the surface of a solid sample
    • Thickness measures of material thin films from several nm to 1 mm (step height measurements)
    • Measurements of surface curvature radius
    • Roughness measurements
    • Residual stress measurements of thin films
    • 3D mapping

Equipment :

Stylus profiling system model: P7 -  KLA
Diamond tipped-stylus : curvature radius of 2 µm

View of the sample holder (at the bottom of image), measure head (top of the image),
view of the tipped-stylus and of the sample (center of image).

 Main Characteristics

•    Vertical resolution (vertical axis) : 1 nm
•    Reproducibility 1.5 nm
•    Total dynamic range : up to 1 mm
•    Scan length (X axis) : from 20 µm to 150 mm
•    Maximum points per scan : 2 millions
•    Sampling rate : 5 to 2000 Hz
•    Stylus force : 0.5 up to 50 mg
•    Lateral resolution 2D (X scan axis) : 25 nm
•    Lateral resolution 3D (Y axis) : 0.5 µm
•    Sample holder chuck diameter : 156 mm
•    Motorized X, Y and Z stages
•    X and Y stages : 2 µm repeatability
•    Motorized théta stage : 360° (résolution 0.1°)
•    Sample height : from several hundreds of micrometers to 50 mm

Example

Measurement of a 86 nm step height standard

(update march 02nd 2023)

Person in charge

Michael PARIS

♮ Solid state nuclear magnetic resonance ('solid state NMR') @P1

♮ Our Solid State NMR facility @P2

♮ Specifications for the 3 spectrometers @P3

♮ Examples of applications in the lab @P4

♮ Collaborations @P5

♮ Access @P6

P1 Solid State Nuclear Magnetic Resonance ('solid state NMR')

NMR is an extremely rich and powerful technique. Its developments have been rewarded by several Nobel prizes in physics, chemistry and medicine. Its principle is based on the study, under an intense magnetic field, of the response of the nuclei (having spin) of atoms subjected to an electromagnetic field. From an experimental point of view, NMR can be applied to both liquid and solid phase samples. There are both pure research and industrial applications, particularly in the pharmaceutical industry. Its higher cost and intrinsic characteristics make solid-state NMR a less widespread technique than liquid-state NMR. However, it remains indispensable for the study of insoluble molecules and solid state materials

The characterisation of materials by NMR provides information on the chemical environment of the elements probed at very local scale (neighbouring atoms or chemical groups). As such, it is a particularly suitable tool for a better understanding of the structure of materials, whether they are crystallised or totally amorphous @E1, in order to establish a link with their physico-chemical properties. Finally, the selective character of NMR (the response of each type of nucleus is acquired separately) can allow the isolation of signatures of environments (interfaces, surfaces, defects) that would not otherwise be observable. @E5

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P2 Our Solid state NMR facility

The solid state NMR facility is composed of 3 spectrometers at 200, 300 and 500 MHz (see specifications @P3). It is part of the Federation RMN Solide Hauts Champs (FR2950 CNRS). The facility is also a privileged entry point for requesting analysis time on higher field spectrometers (IR - Very High Field NMR - FR3050 CNRS). It should be noted that the Pays de la Loire region hosts two other solid state NMR spectrometers - Le Mans University (300 MHz) and INRAE Nantes (400 MHz)..

The 500 MHz spectrometer was the first of the three devices. It was installed in 2003. Its configuration was chosen to be as versatile as possible. Thus, the high field of 500 MHz (11.7 T) allows the acquisition of spectra of quadrupolar nuclei (>70% of the observable nuclei) in good conditions because the width of the lines of these nuclei decreases when the magnetic field increases. In addition, the sensitivity also increases with the field strength. Thus, it is possible to acquire spectra of nuclei having low sensitivity (e.g. low nuclei). The NMR probes were also chosen to allow the versatility of the apparatus. Five probes, including four MAS probes, are available to obtain spectra of low frequency nuclei (low) but also to modulate the size of the rotor (sample holder) and the MAS frequency according to the available volume of the sample to be analysed and the probed nucleus. N.B. The MAS (Magic Angle Spinning) technique consists of rotating a powder sample very rapidly (up to ~100,000 rps) at a precise angle (54.736°) to improve the resolution of the spectra.

Installed in 2010, the 300 MHz spectrometer has strengthened the service by increasing the number of analysis slots. It acquires spectra for which a high-field spectrometer is not necessary or even inappropriate. This latter case is frequently encountered for heavy nuclei such as tin or lead, which show a large chemical shift anisotropy (the higher the field strength, the greater the spread of the spectra). Finally, the presence of two different fields is sometimes essential to unambiguously determine the interaction parameters of the sample analysed. This is the case, for example, for nuclei such as copper or vanadium, which may have chemical shift anisotropy and a quadrupolar interaction of the same order of magnitude. The acquisition of multi-field spectra is of great help in separating these field-dependent interactions. @E4

Also installed in 2010, the 200 MHz spectrometer, due to its weak magnetic field, is a tool particularly suited to the study of battery materials. Since most of these electrode materials are paramagnetic, due to the presence of transition metals (iron, manganese, nickel, etc.), their study is made more difficult, if not impossible, on the two other spectrometers (300 and 500 MHz) at IMN. It is equipped with a high-speed MAS probe.

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P3 Specifications for the 3 spectrometers

• • • • Bruker Avance III 500 MHz Spectometer (11.7 T).  3 chanels  ¹H-¹⁹F/X/Y
        Installed in 2003. Upgrated in 2010
        
        • CP/MAS DVT 2.5 mm probe ¹H-¹⁹F/X   (¹⁵N≤X≤³¹P)
        • CP/MAS DVT 4 mm probe ¹H-¹⁹F/X/Y   (¹⁵N≤X≤³¹P)
        • CP/MAS DVT 4 mm  'low γ' probe ¹H-¹⁹F/X (¹⁰⁹Ag≤X≤³¹P)
        • CP/MAS WVT 7 mm probe ¹H-¹⁹F/X   (¹⁵N≤X≤³¹P)
        • Static  5 mm probe X   (¹⁰⁹Ag≤X≤³¹P)

• • • • Bruker NEO 300 MHz Spectometer (7 T).  2 chanels  ¹H-¹⁹F/X
        Installed in 2010. Upgrated in 2018 (Co-financed by the Région Pays de la Loire and FEDER)
        
        • CP/MAS DVT 2.5 mm probe  ¹H-¹⁹F/X   (¹⁵N≤X≤³¹P)
        • CP/MAS DVT 4 mm probe  ¹H-¹⁹F/X/Y   (¹⁵N≤X≤³¹P)
        • CP/MAS DVT 7 mm probe  ¹H-¹⁹F/X   (¹⁵N≤X≤³¹P)

• • • • Bruker Avance III 200 MHz Spectometer (4.7 T).  2 chanels  ¹H-¹⁹F/X
        Installed in 2010. Upgrated in 2018
        
        • CP/MAS DVT 2.5 mm probe ¹H-¹⁹F/X   (¹⁵N≤X≤³¹P)

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P4 Examples of applications in the lab

Since its creation, the facility has contributed to the characterisation of many types of materials. These include materials for photovoltaics (¹¹⁹ Sn,⁶⁵ Cu,⁷ Li,⁶⁷ Zn,⁷⁷ Se,¹¹³ Cd), polymers (¹³ C), hybrid perovskites (²⁰⁷ Pb,¹¹⁹ Sn,¹³ C,¹⁵ N), materials for batteries (⁷ Li, ⁶Li,¹⁹ F,³¹ P,¹³ C,²⁹ Si), clays (²⁹ Si,²⁷ Al,²³ Na), hydraulic binders or geopolymers (²⁹ Si,²⁷ Al,²³ Na) or even glasses or glass ceramics (¹¹ B,²³ Na,¹⁷ O,²⁹ Si,²⁷ Al,¹⁹ F).

E1 NMR can be used to characterise poorly crystallised or amorphous materials. For example, on the left, ²⁹Si MAS NMR monitoring of the appearance of C-A-S-H cementitious phases over time during lime treatment of a calcium bentonite. On the right, ²⁷Al MAS NMR monitoring of the dehydroxylation of a clay at different calcination temperatures. Middle, determination of the ^IIIB/B^IV ratio by ¹¹B MAS NMR of a borosilicate nuclear glass.

(Update February 24th 2023)

Person in charge

Patricia BERTONCINI

Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM) allow the imaging of a sample surface by scanning a sharp tip localized at less than a few nanometers from the surface. Images recorded are very high resolution maps of different kinds of sample properties. There are several acquisition modes and very different samples can be studied.

Equipments

AFM Nanowizard II JPK Instruments

• • • Scanner
      XY = 100 x 100 µm²
      Z = 15 µm
      Closed-loop

• • • Laser diode
      λ_infra-rouge (850 nm)
    • Modes
      Contact, contact intermittent
      Spetroscopie de force
      Spectroscopie de force longue distance (100 µm)
      Cartographie de force
      Nano-manipulation

 Multimode 8 Nanoscope V de Bruker

• • • 3 Scanners
      XY = 180 x 180 µm2 ; Z = 5 µm
      XY = 10 x 10 µm2 ; Z = 3,3 µm
      XY = 1 x 1 µm2 ; Z = 0,6 µm (résolution atomique sur HOPG ou mica)

• • • Laser diode
      λ_rouge
    • Modes
      Contact, intermittent contact modes
      Force spectroscopy

                                    Modes dedicated to the study of:
                                    - electric and magnetic properties: EFM, MFM, KPFM, C-AFM
                                    - mechanical properties: Peak Force QNM

                                        STM imaging and STS spectroscopy

Examples

Scanning Tunneling Microscopy (STM)

STM allows the imaging of the surface of a conductive material at the atomic scale and in the direct space. The tunneling spectroscopy mode of STM is employed to examine local density of state of the surface.

STM image STM of a surface of 1T-TaS₂, obtained in the constant current mode, at room temperature. The charge density waves superlattice and the atomic lattice can be seen simultaneously. (IMN sample: L. Cario, E. Janod, IMN images: P. Bertoncini).

Magnetic Force Microscopy (MFM)

MFM imaging is obtained using a magnetic tip. The measured forces result from the interactions between the magnetic tip and the sample surface.

Acier Duplex

Height image (left) and MFM phase image (right) of a Duplex steel surface showing magnetic domains (IMN sample: E. Bertrand, P. Paillard, IMN images: P. Bertoncini).

Nano-manipulation

The AFM tip can be used as a manipulation tool… For example, the logo of the Institut des Matériaux Jean Rouxel has been engraved drawn by following the chosen pattern while applying a pressure on the polymer surface.

Height images of a polycarbonate film surface before (left) and after « gravure » (right). (IMN images IMN : P. Bertoncini).

Mapping of the mechanical properties using force spectroscopy

AFM allows the recording of Force-Distance curves by approaching and withdrawing the AFM tip. Approach curves permit to determine the sample surface topography, quantify mechanical deformation and extract elastic modulus. Retract curves allow the measurements of adhesion and interaction forces, stretch molecules…

Example of force-distance curves (approach, in grey and retract, in black) recorded while bringing into contact a living cell (immobilized on a microlever) to a Petri dish surface before being detached (IMN curves: P. Bertoncini).