DNP RMN des Solides Instrumentation - Bruker · Innovation with Integrity DNP RMN des Solides...

Innovation with Integrity

DNP RMN des Solides Instrumentation

30ème Réunion Utilisateurs RMN, 29 et 30 novembre 2016, Paris

Fabien AUSSENAC, Applications RMN

30ème Réunion Utilisateurs RMN – 29-30 novembre 2016 – Maison de la Chimie, Paris

• Low nuclear polarization (P) at thermal equilibrium

B0

12

12

E DE

9.4 T (400 MHz) T=300 K

Spins difference between the 2 energy levels

is only 32 over 1 million!

Spin 1/2 nucleus in B0 magnetic field

● ● ● ●

● ● ● ● ●

Increasing the Sensitivity of NMR

• Pulses sequences

Transferts CP, INEPT

• High magnetic field

S/N B03/2 23.5 T, 1 GHz

• Reduction of electronic noise

Cryoprobe S/N ≈ factor 4


Increasing the Sensitivity of NMR Hyperpolarization

● Ultra Low Temperature (few mK) ● Optical pumping (3He, 129Xe, MRI applications) ● Para Hydrogen Induced Polarization (PHIP)

● Dynamic Nuclear Polarisation (DNP)

Figure: Münnemann, Nature Physics, 2011, 7, 522

Hyperpolarization


DNP: Dynamic Nuclear Polarization

• Transfer high electron polarization to nuclei:

• Irradiate at EPR frequency (GHz)

• Detect at NMR frequency (MHz)

• High potential gain in sensitivity: 10-100’s+

• Solid State DNP spectrometers: E B0

EPR

NMR

NMR

Magnetic Field

Microwave

Frequency

1H NMR

Frequency

9.4 T 263 GHz 400 MHz

14.1 T 395 GHz 600 MHz

18.8 T 527 GHz 800 MHz


Solid-State DNP Spectrometer

Gyrotron

LT-MAS DNP probe

Transmission line

MAS cooling system

Rosay et al., Phys. Chem. Chem. Phys., 2010, 12, 5850 Rosay et al., J. Magn. Reson., 2016, 264, 88


Solid-State DNP Spectrometer

Microwave source Gyrotron

DNP Probe

NMR Magnet

Low-temperature Magic Angle Spinning (LTMAS) Cabinet


Gyrotrons for DNP-NMR Applications

Gyrotron Schematic

ELECTRON GUN

ANODE

CAVITY

LAUNCHER

MIRRORS

MILLIMETER WAVES

WINDOW

COLLECTOR

ELECTRON BEAM

SUPERCONDUCTING MAGNET

• DNP gyrotrons introduced by Robert Griffin and Richard Temkin at MIT

mc

eB

c

cRF harmonicnn

0

,~


395 GHz DNP signal enhancement as a function of microwave power Sample: 1 M of 13C Urea in glycerol-d8/D2O/H2O

(60/30/10) with 10 mM AMUPol 108 K, 12 kHz, 3.2mm sapphire rotor

Gyrotron Microwaves Power Curve


Gyrotron Magnet

9.7 T magnet

(527 GHz second harmonic)


• Push button user interface: ON/OFF/Standby

• Controls and regulation:

• Temperatures, voltages, water cooling, gyrotron magnet

• Output power stabilization

Gyrotron Control System


263, 395, 527 GHz Solids DNP

1H NMR WB NMR Magnet

Gyrotron Frequency

Harmonic Gyrotron magnet

400 MHz 400/89 Ascend DNP

263 GHz 2nd 4.8 T cryogen-free

600 MHz 600/89 Ascend DNP

395 GHz 2nd 7.2 T cryogen-free

800 MHz 800/89 USP RS 527 GHz 2nd 9.7 T cryogen-free

• Second-harmonic with cryogen-free gyrotron magnets for all frequencies:

– Combined site planning guide 263, 395 and 527 GHz

– Yearly control system/high voltage safety service visit. Gyrotron magnet

service required every 2 years

• Sweep coils on all new DNP NMR magnets

• Plus LTMAS cooling system and DNP probe

• Applications areas: biological solids and material science with enhanced sensitivity


Sweep coils on all New DNP NMR Magnets

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

398.7 398.9 399.1 399.3 399.5 399.7 399.9 400.1 400.3 400.5

1H Frequency (MHz)

Field dependence curve on 13C Proline in glycerol-d8/D2O/H2O with 15 mM TOTAPOL

400 MHz/263 GHz

DN

P g

ain

(a.

u.)

Power supply

• Different radicals • Samples with endogenous radicals

• Direct DNP on X nuclei

400 DNP Ascend ± 750 Gauss


• Available for different rotor sizes: 3.2 mm (28 μL, 15 kHz) 1.9 mm (10 μL, 25 kHz) 1.3 mm (2 μL, 40 kHz)

• H/X/Y and H/X WB probes

• Low sample temperature and R.F. circuit ~100 K

• Cold insert/eject capability

• Individual heaters for VT, bearing

and drive gases for optimal temp. control

• Waveguide for microwave irradiation

• Long term operation (days, weeks)

Low temperature (LT) MAS DNP Probe


Axial cross section of a 3.2mm MAS system

Upper part of a 3.2mm LT-MAS DNP probe

LT-MAS DNP Probe


LT-MAS DNP Probe

Probe Base

Microwave Waveguide from Gyrotron

Cold Gas and Vacuum Lines From LTMAS Cabinet


DNP MAS Rotors

• 3.2 mm: sapphire rotors, zirconium oxide drive caps

• Silicon plugs inserts

• Teflon inserts

• 1.9 & 1.3 mm: zirconia rotors, Vespel drive & bottom caps

1.3 mm

2 mL

40 kHz


LT-MAS Heat Exchanger

he

Heat

Chamber heater

Pt100 detects

LN2 filling level

Warm gas in at

2 bar

Cold gas outlet

Exchanger Coil

Chamber P=2.5 bar Boiling @ T= 90 K

60L LN2 Dewar @ 77K

Pressure sense

condensation

P. Allen, F. Creuzet, H.J.M. deGroot, R.G. Griffin, J. Magn. Reson., 1991, 92, 614

• Pressurized heat exchanger chambers

• Automatic refill of liquid nitrogen supply


● Twelve 263 GHz/ 400 MHz ● Ten 395 GHz/ 600 MHz ● Five 527 GHz/ 800 MHz

527 GHz/ 800 MHz

Solid-State DNP Spectrometers 27 Installed Spectrometers WW (Oct. 2016)

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