EPR/ESR method and techniques

Importance !

      The ESR continues playing an essential role in top scientific fields such as: the physical phenomena taking place in nanometric particles, characterization of semiconductor and dielectric nanomaterials and nanostructures with applications in nanoelectronics and nanophotonics, including quantum computing, of materials for radiation detection and conversion, the production of new catalysts, biomolecules and biomaterials investigation, the creation of new medicines, in the understanding of living organisms functioning.

What is EPR/ESR ?

     The Electron Spin Resonance Spectroscopy (ESR), also known as Electron Paramagnetic Resonance (EPR) is an assembly of experimental methods and spectroscopic techniques based on the observation of the microwave absorption (f > 1 GHz) associated to transitions between energy levels in magnetic field of the electron systems with spin different from zero from atoms/ions and molecules, free or embedded in condensed matter, as well as from point (atomic) defects in the crystalline lattices of solid materials.
     Since the ESR phenomenon observation in 1944, a discovery associated to the radar invention, the ESR spectrometers performances have been improved in a spectacular way, due to the progress in the high frequency electronics, in the large scale employment of the integrated circuits and microprocessors, in the use of hybrid electronic and (quasi) optical circuits at frequencies over 100 GHz, simultaneously with the employment of superconducting magnets for obtaining magnetic fields of more than 2┬áT. The emergence of powerful PC computers at reasonable costs lead to the digital control of the ESR spectrometers and the on-line recording and analysis of the spectral data with sophisticated software. In parallel, new double and triple resonance experimental techniques were developed, as well as pulsed techniques, that allowed the spectral resolution increase, the possibility of observation of extremely small variations (< 10-8 of the quanta energies associated with the investigated ESR transitions) in the interactions and energy transfer. This development increased the applications range in the characterization of nanoparticles and nanomaterials, photocatalysis, biochemistry and biology.

What are we doing ?

     Various multifrequency and multiresonance ESR experiments in the temperature range of 3.8 K < T < 500 K, using recently installed Bruker spectrometers:

  • Continuous wave (CW) ESR experiments in the X (9 GHz) and Q (34 GHz) microwave frequency bands.

  • CW multiresonance ENDOR (Electron Nuclear Double Resonance) , triple resonance and EIE (ENDOR induced ESR) in the Q (34 GHz) microwave frequency band.

  • Fourier Transform (FT) pulsed ESR, such as: ESE (Electron Spin Echo), FID (Free Induced Decay), ESEEM (Electron Spin Echo Envelope Modulation), or 2D_HYSCORE experiments in the X (9 GHz) microwave frequency band.

  • Pulsed ENDOR, ELDOR (Electron-Electron Double Resonance), DEER (Double Electron-Electron Resonance) and related (Time Domain pulsed ENDOR, Nuclear Spin Echo, Transient Nutation, Nuclear Spin FID) experiments in the X (9 GHz) microwave frequency band.