Dear Easy spin community,
I am having Fe(III) S=1/2 low spin system with S=5/2 high spin impurity. I tried to do two component fitting. Here g 2.21 corresponds to isotropic low spin and 4.97, 2.16, 1.98 corresponds to high spin peaks. I have to add small D and use isotropic g value. Unfortunately if I use the parameters mentioned below, I am not getting splitting at low field. Am I missing any concepts? Any help improving the simulation will be highly appreciated. Thanks in Advance.
clear all;
clc;
% Constants
clight = 299792458; % Speed of light in m/s
convfact = (clight * 100) / 1e6; % Conversion from cm⁻¹ to MHz
% Fe(III) S = 1/2 (Main Component)
Fe_Main.S = 1/2;
Fe_Main.g = [2.15];
Fe_Main.lw = [2.5 6];
Fe_Main.weight = 0.75;
% Hyperfine Coupling (MHz)
Fe_Main.Nucs = 'Fe'; % Nucleus: 56Fe
Fe_Main.A = [70 70];
% Fe(III) S = 5/2 (Impurity Component)
Fe_Impurity.S = 5/2;
Fe_Impurity.g = [2.18 2.10 2.0];
Fe_Impurity.D = [0.7 0.0] * convfact;
Fe_Impurity.lw = [2 5.5];
Fe_Impurity.weight = 0.25;
Fe_Impurity.Nucs = '56Fe';
Fe_Impurity.gStrain = [0.08 0.02 0.03];
% Experimental Parameters
Exp.mwFreq = 9.138; % GHz
Exp.nPoints = 65536; % Number of points
Exp.Range = [0.0099 990];
Exp.Temperature = 77; % K
Exp.Harmonic = 1;
% Load Experimental Data
[B_exp, spec_exp] = textread('Fe-III-OOR.txt', '%f %f', 'headerlines', 0);
% Simulated Spectrum
[B, spec_sim] = pepper({Fe_Main, Fe_Impurity}, Exp);
% Normalize & Scale Intensity
spec_sim = spec_sim / max(abs(spec_sim));
spec_exp = spec_exp / max(abs(spec_exp));
scale_factor = max(abs(spec_exp)) / max(abs(spec_sim));
spec_sim = spec_sim * scale_factor;
% Plot Experimental vs. Simulated
figure;
hold on;
plot(B, spec_sim, 'r', 'LineWidth', 1.5); % Simulated (red)
plot(B_exp, spec_exp, 'k', 'LineWidth', 1); % Experimental (black)
xlabel('Magnetic Field (mT)');
ylabel('Intensity (a.u.)');
legend('Simulated', 'Experimental');
title('Fe(III) EPR Spectrum - Adjusted Parameters');
hold off;