Novel EPR methods

We aim at developing novel techniques and instruments for the characterization of materials using Electron Paramagnetic Resonance. We are working on three separate setups:

 

PulsedLaserESR

Transient ESR setup

Transient electron paramagnetic resonance: where the electronic excited states of the material become accessible by sending sequences of powerful optical and microwave pulses (available microwave frequencies are 9-10 GHz (X-band), 34 (Q-band) and 93 GHz (W-band)). A time resolution of ca. 10 ns is achieved, allowing the assessment of the coherent spin dynamics of molecular magnetic compounds. The system is being cared for and updated by Michael Slota.

As ESR spectrometer we use Bruker ElexSys systems E580 and E680 hosted in CAESR. More information on these systems can be found on the CAESR website. We use a seeded nanosecond Nd:YAG laser (Newport Spectra-Physics Quanta-Ray LAB) to pump an optical parametric oscillator (VersaScan and UVScan, Newport Spectra-Physics GWU).

Laser specifications:

  • Tunable wavelength 210 nm to 2850 nm
  • 4-7 ns pulses
  • 22 Hz repetition rate
  • Pulse energies up to 60 mJ (wavelength dependent)
  • Efficient home-built fiber coupling

 

dil2

Triton 200 dilution refrigerator

Ultrabroadband electron paramagnetic resonance at mK temperatures: With this technique it is possible to tune both the frequency and the magnetic field, so as to create a full diagram that shows the continuous evolution of the spin levels. The technique makes use of striplines micro-fabricated onto Si wafers and allows working at temperatures down to 20 mK, while tuning the frequency from 100 MHz to 67 GHz. The system is equipped with a vector magnetic field (10-10-60 kOe) and allows fast exchange of samples. We plan to upgrade it to a pulsed system so as to achieve multi-frequency ns time resolution.

 

Single-molecule electron paramagnetic resonance: we aim at achieving the ultimate detection limit of electron paramagnetic resonance by performing EPR measurements at electron temperatures of 40 mK. This is a work in progress, and a central part of Nicola Dotti‘s PhD thesis.

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