Facilities and equipment.

The EPSRC NRF for EPR at Manchester currently has seven spectrometer platforms, allowing for continuous wave (c.w.) EPR at L-, S-, X-, K-, Q-band along with pulsed EPR at S, X and Q-band. In-situ sample temperatures can range from < 2 K to 1200 K, alongside many additional experimental options. (please see below for specifics)

The seven base platforms consist of:

An EMXPlus with 1.8 T electromagnet; for c.w. L-,S- X-, K- and Q-band.
An Elexsys E580 with 1.8 T electromagnet; for c.w. and pulsed S- and Q-band.
An Elexsys E580 with 1.8 T electromagnet; for c.w. and pulsed X-band.
An Elexsys E580 with 1.8 T electromagnet, for c.w and pulsed X band.
An Elexsys E500 with 1.8 T electromagnet for c.w. S-, X-, K- and Q-band and X band RapidScan.
An EMX Micro with 1.2 T electromagnet, for c.w. X-band EPR and temperatures between 100- 1200 K
An ESR5000 benchtop with 0.65 T electromagnet for c.w. X-band at temperatures between 100 K and 500 K and equipped with a robotic autosampler option.

Due to the modular nature of the EPR platforms, the frequencies/techniques available on each platform can be varied according to capacity, capability or geometry requirements.

The EPR NRF possesses over 30 EPR resonators to be able to optimise sample size, optical access or for specific techniques, (e.g. parallel mode, ENDOR).

Pulsed EPR:

All of our pulsed capable platforms have integrated Arbitrary Waveform Generators (Bruker AWG-I) allowing for the shaping, correction or frequency sweeping of microwave pulses.

All pulsed capable platforms are fitted with diode circuitry allowing the ability to use MPFU/AWG and ELDOR pulses simultaneously removing coherency artefacts.

All pulsed capable platforms have the latest SpecJet III digitiser alongside 1 GHz video amplifiers. These can be reverted to 200 MHz where cut-off-filtering is required.

New for 2024, is a Q band loop-gap resonator promising better bandwidth, and shorter pulse lengths.

Additional experimental options:

Sample cooling via both 'wet' and closed-cycle helium cryostats:
- All full-sized platforms are Closed-Cycle cryocooled, routinely achieving temperatures <2 K at L-, S-, K-, Q-band. (using Flexline resonators)
- Due to their geometry, SHQ 'square' cavities at X-band are limited to 4.2 K
- The facility maintains wet cryostats, and where required, Liquid Helium usage allows for 1.8 K at all frequencies.
In-situ sample heating is available on two platforms enabling temperatures of up to 1200 K at X-band (using the high-temperature resonator)
- Temperatures of 100 - 600 K are routinely achievable without change of resonator.
Single crystal mounts and goniometers for in-situ sample rotation.
Flow cells for probing short-lived or regenerated samples.
Flat cells and multi-bore quartz tubing for handling highly dielectric samples
Parallel and perpendicular mode modulation at X-band.
In situ electrochemical generation at all frequencies.
In-situ sample irradiation is available at all frequencies and temperatures via multiple (and simultaneous) methodologies.
- Fibre optic delivery
- Direct LED/broadband/laser delivery through
- Using the EPR tube itself as a light guide.
The EPR NRF has 3 OPO lasers of varying power and repetition rate (tuneable from 190-2400 nm, up-to 60 Hz), to best match the desired wavelength/power requirements of the experiment.
For continuous illumination, the EPR NRF has a variety of LEDs, broadband Xenon lamps which can be modulated and filtered as required.

Sample handling and delivery:

The Facility has a sample preparation room available in the Photon Science Institute, equipped with fume hood and Schlenk line, alongside full access to the chemical laboratories of our collaborators in the adjacent Department of Chemistry where required.

Therefore we can handle a wide range of sample types, including samples that are sensitive to temperature, atmosphere, light, solvent loss, and a wide range of sample hazards, including toxic, biological and low-level radioactive materials.

For samples which must be kept cold during transport, the EPR NRF has the ability to send/receive a dry shipper which will keep samples at liquid nitrogen temperatures (without liquid) enabling delivery around the UK.

For air sensitive samples, decanting and sealing into EPR tubes can be arranged via the University's glassblowing team or via our collaborators in the Chemistry department.

Future upgrades:

Newly arrived for 2024 is RapidScan capability at X-band, alongside an X- band portable benchtop-sized system with autosampler.
2025 will see the arrival of L-band (1.1 GHz) pulse, a second benchtop system equipped with an automated goniometer and the Bruker HD100 Multiharmonic detection accessory.
Late 2025 should see the arrival of a second Q band pulse bridge.

Collaborative arrangements for other EPR experiments:

We work closely with our equipment partners and the EPR community to stay up-to-date with the latest developments and can guide users to appropriate contacts.

Pulsed W-band spectroscopy, in collaboration with Professor Christiane Timmel at the University of Oxford CAESR group.
Pulsed methods, including at high frequency, with Dr G. Smith at the St Andrews HIPER project.
Very high frequency (53 GHz to >1 THz; 0 – 16 T; 1.5 to 280 K) c.w. EPR, with Dr A-L. Barra of the LNCMI (high magnetic field laboratory) CNRS in Grenoble.
Frequency domain EPR (100 – 850 GHz; 1.8 – 300 K) spectrometer, with Prof J. van Slageren, University of Stuttgart.
EPR imaging guidance can be arranged with Bruker.

Non-EPR equipment

The EPR NRF also houses a Quantum Design MPMS3 SQUID magnetometer to conduct complementary bulk magnetic measurements alongside EPR characterisation.
- This system is also optioned with the AC, oven, crystal rotator, ULF and in-situ light irradiation options.
The EPR NRF also possess a Cary60 UV-Vis spectrometer to assist in optimising light irradiation measurements.
- This can be combined with our optical cryostat to achieve low temperature measurements.