Solid state nuclear magnetic resonance (english version)

(update march 02nd 2023)

Person in charge

Michael PARIS

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♮ 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

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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.