ELECTRON PARAMAGNETIC RESONANCE SPECTROSCOPY
Technical Supervisor: Alberto Vilchez
The electron paramagnetic resonance spectroscopy (EPR) or electron spin resonance (ESR) allows detecting and studying stable or transient paramagnetic species such as free radicals, some transition metal ions and defects in materials in a wide range of temperatures. Thus EPR crosses
several disciplines including: chemistry, physics, biology, materials science and medical science.
The free radicals are often short-lived, but still play crucial roles in many processes such as photosynthesis, oxidation, catalysis, and polymerization reactions.
The electron paramagnetic resonance studies the interaction of a paramagnetic species with the electromagnetic radiation (microwave radiation) in the presence of an external magnetic field. It detects and measures the transition between energy levels of the two orientations of the spin-electron. The spectrometer records the net absorption energy of this transition.
An EPR spectrum can provide the following information: Unequivocal detection of paramagnetic species, species identification, distinction between free radicals and paramagnetic transition metals, detection of free radicals of short half-life (spin trapping), quantified information on the ‘geometric and electronic structure, etc…
Spectra can be acquired from solid powder, tissues or solutions at temperatures between 4 K and above room temperature.
Alberto Vílchez
Technical Supervisor
alberto.vilchez@iqac.csic.es
SERVICES
- Characterization of stable and persistent free radicals, poliradicals, radical cations and radical anions
- Study of dopped conducting polymers and organic magnetic materials with novel optical, electronic and magnetic properties.
- Macromolecular polyradicals as potencial applications as hosts molecules in suprastructures and porous materials
- Stable radical adducts with bipolar transport properties in glassy morphological states
- Study of new organic materials with non-linear optical properties
- Spin trapping detecction of transient radical species (cyclopropenyl radicals)
- Radical mechanism reaction by spin trapping
- Detection of stable free radicals in merina wool fabrics
- Skin and hair detecction of UV generated radicals, and application of antioxidants and UV filters
- Reaction kinetics determination
- Study of new functionalized and strongly oxidant persistent radicals, as chemosensors of the antioxidant power of polyphenoles
- Use of spin trap method and EPR spectroscopy as the analytical tool to measure the radical scavenging activity of natural products with antioxidant properties
EQUIPMENT
Unit EPR
EPR/ESR spectrometer EMX of Bruker, with a microwave bridge of X-band (~9 GHz) EMX premium X, magnet of 10” ER073 with a power supply of 12 KW ER083.
The following accessories are available:
- Standard cavity
- Double cavity
- Several container samples (quartz tubes, quartz capillaries, cells, flat cells for tissue)
- Liquid nitrogen dewar
- Continuous flow cryostat system of liquid helium (4.2 K – 300 K)
- High vacuum unit HP40B2 from Vacuubrand
- Liquid nitrogen variable temperature accesory: cryostat, liquid nitrogen transfer line… (120 K – 520 K)
– Intelligent temperature controler ITC 503S from Oxford Instruments - Gas flow controller from Oxford Instruments
- “In situ” radiation source of UV-vis. 500 W Oriel pressure mercury lamp. Power supply Newport 69910
- Bruker software acquisition, processing and simulation spectra WINEPR and SimFonia.
IQAC
Institut de Química Avançada de Catalunya
c/ Jordi Girona 18-26
08034 Barcelona - Spain
Ph: +34 93 400 61 00
Fax: +34 93 204 59 04