EasySpin forum

Forgive my inexperience with matlab and Easyspin and thank you for this free resource. The EasySpin forums are making it into my thesis acknowledgements for sure.

We collected an experimental spectrum of a suspected homogeneous Mn(0) radical with N donor ligands at room temp in 2MeTHF. We should expect a lot of coupling from Mn (5/2) and 4 nitrogens however, the collected spectrum is very broad and lacks any real coupling, maybe as expected. To confirm our suspicions we simulated the EPR using ORCA and when inputting it into EasySpin, it looks entirely different. That is, until we increase the lw to very high, 50 mT or above, when it actually starts to resemble the experimental. My question is this: how much lw is too much lw? Is it appropriate to keep increasing the lw until it matches the experimental?

Here is my script and a picture of the experimental is attached.

Sys = orca2easyspin('EPR-mono2.prop',0.5)
Sys = nucspinkeep(Sys, [1 2 4 7])
Exp.mwFreq = 9.85
Sys.lw = [50]
%tcorr = 5e-10
Exp.Range = [200 500]
garlic(Sys,Exp)

The large linewidth points to static or dynamic heterogeneity in your sample. The ORCA calculation does not capture this - in fact, it does capture any heterogeneity, since it calculates parameter for a single molecule with fixed and static geometry.

It's crucial to understand the physical reason behind the large line width. That's a question that neither ORCA or EasySpin can answer directly.

Stefan Stoll wrote: ↑Fri Jan 14, 2022 12:10 pm

The large linewidth points to static or dynamic heterogeneity in your sample. The ORCA calculation does not capture this - in fact, it does capture any heterogeneity, since it calculates parameter for a single molecule with fixed and static geometry.

It's crucial to understand the physical reason behind the large line width. That's a question that neither ORCA or EasySpin can answer directly.

Thanks for the reply, you are a river to your people!

When you say heterogeneity, do you mean with the phase of the material? ie a solid could be forming? The large linewidth persists even when cooled to 77K in a glassy solvent (2MeTHF) but crashing out of solution is an issue with this compound and reduced concentrations aren't easily attainable. Could you please point me in a direction for understanding the issues with the large linewdith? And where it could be stemming from?