EasySpin forum

Hi!

I am trying to simulate EDNMR spectra of 55Mn that interact with S=3 and D~-0.3 cm^-1. There are shifts between the simulated and the experimental spectra about 4-7 MHz. I have tried to decrease the Excitation window, add quadrapole, rotate the AFrame.. Nothing worked.. What else could I try?

Have you adjusted the hyperfine values? Post a minimal but working script that shows what you are asking about.

The problem is these shifts from the experimental that are marked with red.



Sys.S = 3;
Sys.g = 1.99;
Sys.D = -3e4*[0.281 0.0461];
Sys.aF = [20 -40];

Sys.Nucs='55Mn';
Opt.nKnots=[20 3];
Opt.Method = 'matrix';
Opt.Threshold=1e-4;


Par=struct('ExciteWidth',100,'nPoints',1024,'Harmonic',0,'Temperature',4.8);
Par.mwFreq=94.017;
Par.Range=[0 300];

A=[-95 -97 -91;-102 -103 -97];
lw=[5;5]; scal=[ 0.5 0.5];


for n=1:2;
Par.Field = 1980;
Sys.A=A(n,:)
Sys.lwEndor=lw(n,:);
[x198,MnSim198] = salt(Sys,Par,Opt); MnSim198=MnSim198/max(MnSim198);
LOR= gaussian(x198,0,300);LOR=LOR/max(LOR);
MnSimA198(:,n)=scal(n)*LOR.*MnSim198;
plot(x198,MnSimA198(:,n)-0.1); hold on
end


I cannot add the experimental file.. Thank you!

You are simulating an ENDOR spectrum and comparing it to an EDNMR spectrum. The simulation is likely off in the orientation selection and the line intensities.

This is with ExciteWidth=1 and nKnots=[180 6], but it is still the same..

There is a small term missing from the hamiltonian i am using.
For example, for the smaller hyperfine. The experimental peaks are 162MHz and 256 MHz.
It should be: 2A-ω=162 and 3A-ω=256 and 256-162=A
ω~21MHz

The A calculated from each equation is slightly different: 91.5 92.5 94

You might be seeing crossterms between zero-field splitting and hyperfine coupling.

what does this mean? I don't understand..

The presence of significant zero-field splitting (S>=1) will affect the quantization axis of the electron spin, which in turn affects the nuclear resonance frequencies via the hyperfine coupling. As a result, the nuclear peaks are slightly shifted compared to the case S=1/2.

But, this isn't calculated by easyspin already?

I corrected a bit the intensities.. for the peak positions I can't do anything..