A fingerprint of the ion and its surroundings
Many metal ions have unpaired electrons, so they give an EPR spectrum. The position, the splitting and the shape of the spectrum depend on which ion it is, in which oxidation state, and what surrounds it. Each ion therefore has a recognisable pattern.
Where it is used
- Catalysts and catalyst supports, before, during and after use
- Metal complexes and coordination compounds
- Semiconductors and other solids with defects
- Carbon materials
- Minerals, soils and natural samples with trace metals
Typical tasks are checking the oxidation state of a catalyst, studying the environment around an ion, finding paramagnetic defects, and detecting trace metal contamination.
Seeing only the states that have unpaired electrons
A change of oxidation state often changes the number of unpaired electrons. Copper(II) gives a strong signal, while copper(I) has none. A catalyst can therefore be checked before and after a reaction, and the disappearance or appearance of a signal shows directly which state it is in.
What it adds
- Selective for paramagnetic centres, even at low concentration in a complex sample
- Gives information about the oxidation state and the local environment, not only the amount
- Non-destructive, with little sample preparation
- Benchtop instruments make routine checks practical
Points that matter in practice
- Absence of a signal does not mean absence of the metal. Some oxidation states, such as copper(I), give none
- Overlapping signals of several species can be separated with spectral simulation and fitting
- Spectra of powders and frozen solutions are broad and complex, and the analysis takes some experience
- Some ions give very broad lines and are best measured at low temperature, which needs a suitable accessory
- Quantification needs a reference sample and identical measurement conditions
From your question to a routine method
Describe your samples and your question. MSY Consulting runs feasibility measurements, shows what the technique can and cannot tell you in your case, and supports you with the analysis until the method is part of your routine.
Let's talk about your application
Send an email describing your instrument and your application, and you will get a reply.
contact@msyconsulting.euMSY CONSULTING SAS · Wissembourg, France · LinkedIn