Fitting semi-quinone anion type

[Zackou]

Dear all,

I'm trying to simulate the EPR spectrum (Q-band) for a semi-quinone anion radical type using "pepper". Unfortunatly, the results differs from the experimental one around g = 2.0046...

I have tried to put some HStrain, gStrain... but anyway, the results still differ from my experimental data.

How do you think I can improve the simulation ? Any help would be greatly appreciated.

The code is as below and the experimental data (.DSC and .DTA) is attached.

Thank you in advance for your attention to this matter,

Best regards,

Zackou

Code: Select all

clear all
close all
clc

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                      Experimental
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[B,spec,parwt] = eprload('SQ');
spec = real(spec);
spec = basecorr(spec);

freqexp=parwt.MWFQ/1e9; 

deltaB= 14 ;%G 
B=(B+deltaB)/10; %mT


normspec=rescale(spec,'minmax'); % min=0, max=1


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                        Simulation 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%% Semi quinone %%%%%%%%
Sys1.S=5/2; 
Sys1.g=[2.0059 2.0046 2.0023];
Sys1.lwpp = [0 0.2];

Exp=struct('Range',[B(1) B(end)],'mwFreq',freqexp);
Exp.Harmonic = 1;


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                   Plot Sim VS Exp
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


[x,y]=pepper(Sys1,Exp);
normy=rescale(y,'minmax'); %min=0 et max=1

figure(1)
spectrum = plot(B,normspec,'k',x,normy,'m','linewidth',2);
legend('exp','simul');
title('Semi quinone 20 dB');
xlabel('Magnetic field [mT]');
set(gca,'YTick',NaN,'ylim',[-0.1 1.1]);
moveit2(spectrum);

[Stefan Stoll]

It could be that your experimental spectrum shows passage/saturation effects. Check whether the baseline is clean when you look at
plot(cumsum(real(spec))).

[Zackou]

Thank you Stefan for your attention,

The baseline is not clean as you can see in the .jpg attached.

Moreover, I think it's possible that there is another component that overlaps with this semi-quinone anion type.

Best regards,

Zackou