EasySpin forum

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% Fitting easyspin functions using lsqcurvefit
clear;

% open file, if you use open file:
% [StrFile,StrDir,FilterIndex] = uigetfile('*.spe','Open file','c:\Users\Dusan\Documents\EPRmerenja\Marija ZoranSap');
% StrFullPath = [StrDir StrFile];
% open file, if you use direct link from HD 
StrFullPath = 'c:\Users\Dusan\Documents\EPRmerenja\Marija ZoranSap\Pani.spe'; % your path here!
[B,I,param]=eprload(StrFullPath);
% File can be found at https://www.dropbox.com/s/7h4rzln5r20egzw/Pani.spe?dl=0

I=(I-I(1))*100/param.Gain;
% Initial values
Ip = 40000; g0p = 2.001; DBp = 0.3; Cp = 0;
initial = [Ip, g0p, DBp, Cp];
LB = [10 2.0000 0.01 -1000]; UB = [400000 2.005 1 1000];

% Fitting Easyspin single Lor line
FitES = lsqcurvefit(@fEasyspinForumLor, initial, B, I,LB,UB);
IinitialES = fEasyspinForumLor(initial,B);
IFittedES = fEasyspinForumLor(FitES,B);

% Fitting with Lorentzian
FitLor = lsqcurvefit(@fLorForum, initial, B, I,LB,UB);
IinitialLor = fLorForum(initial,B);
IFittedLor = fLorForum(FitLor,B);

% Plot experimental, initial and fitted curve
figure;
plot(B,I,'c','linewidth',5,'DisplayName','Exp'); hold on;
plot(B,IinitialES,'b--','linewidth',4,'DisplayName','ES init.'); hold on;
plot(B,IFittedES,'b','linewidth',3,'DisplayName','ES fitted');  hold on;
plot(B,IinitialLor,'r--','linewidth',3,'DisplayName','Lor init.'); hold on;
plot(B,IFittedLor,'r','linewidth',2,'DisplayName','Lor fitted'); % hold on;
legend('show');
grid on;

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% Lorentzian plus constant
function y = fLorForum(cc,x)

frek = 9.361;
B0 = mhz2mt(frek *1000) * gfree / cc(2); % from g to B
y=-(2*(cc(1)/pi)*cc(3)*(x-B0))./(cc(3)^2 + (x-B0).^2).^2 + cc(4); % derivative Lor, version with int ~ I only. 
% Identical to easysin version according to documentation.
end

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%Easyspin Lorentzian 

function y = fEasyspinForumLor(c,x)

Exp.mwFreq = 9.361; % frequency
% gg = (mhz2mt(frek *1000) / c(2)) * gfree; % ovo prebacuje B u g
Exp.Range = [x(1) x(end)];
Exp.nPoints = length(x);
Sys.g = c(2);
Sys.lw = [0 c(3)*2];
[xP,yP1] = pepper(Sys,Exp);
y = c(1) * 1.807713 * yP1 / 1000 +c(4);
y = y.';
end