Laboratory for Structural Elucidation  - LAE

 

 

Laboratory for Electron Paramagnetic Resonance Spectrometry

 

Contacts Lic Mariana Andrade, email:  lrmn@cemup.up.pt

                   Scientific Supervisor:   Prof. Maria Conceição Rangel, email: mcrangel@fc.up.pt

          

Laboratory access and services rules:  Rules for Access and Services (pdf)  

                                                                     Access, Services and Training

 

Equipment

Electron Paramagnetic Resonance Spectrometer 

BRUKER  ELEXYS III E580 operating in the frequencies of the X-band (9.5 GHz) and Q-band (35 GHz).

The spectrometer is designed for the analysis of samples in the liquid phase and in the solid phase and is equipped with variable temperature units that allow the operation in the range of 77 to 400 K.

 

The spectrometer can operate in the X-band or in the Q-band using two cavities:

a) a cavity for the X-band with high resolution (SHQ)
b) a cavity for the Q-band

Experimental methods

The Electron Paramagnetic Resonance Spectrometry (EPR) allows the analysis of paramagnetic samples, that means species with unpaired electrons.

The Electron Paramagnetic Resonance Spectrometry (EPR) allows the identification and characterisation of species with a variable number of unpaired electrons  and provides information about the electronic structure of the paramagnetic species and the neighbour nucleus, as long as the nuclear spin is different from zero and the nature of the fundamental electronic state makes it possible.

 

Sample requirements and preparation

Samples for analysis must be in the liquid phase or solid phase. The solid phase generally requires magnetic dilution, unless the sample paramagnetic species is naturally diluted.

The solutions must be preferentially prepared with solvents of low dielectric coefficient and previously air degassed to avoid contamination with molecular oxygen. The concentration of sample that is needed  depends on the nature of the species of interest, and typically is from 10-3 to 10-5 M.

Specific information can be obtained in several websites dedicated to EPR experiments or directly with us.

 

Typical sample volume used for X-band is about 5 ml and the samples are analysed in quartz tubes (3mm of diameter and 140 mm length). The nature of the solvent may require the use of tubes of smaller volume. For the Q-band the samples are analysed in capillary tube

 

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