Сreating a model for an experiment 2pESEEM

[Yliya Ermakova]

An ESEEM experiment was conducted with 2pESEEM. I'm trying to create a model to describe this experiment, but I don't understand which parameter is responsible for the intensity of the modulations. I am attaching a code in which my experiment is shown in black on the first graph, and the model is shown in red. In the second graph, I take the Fourier transform to see if the model fits into the experiment. Tell me a system parameter that will help me increase the intensity of the echo signal modulation.

clear; clf; clc;

% 1. Загрузка и подготовка данных
D = readmatrix('C:\Users\ЮЛИЯ\Desktop\MatLab\eseem\231219a04.dat');
time_exp = D(:,1) / 1000; % Перевод в микросекунды
signal_exp = D(:,2) / max(D(:,2)); % Нормировка

% 2. Параметры системы NV-центра
Sys.S = 1; Sys.g = 2.0047; Sys.Q = 2.53; Sys.D = 1285;
Sys.Nucs = '14N'; Sys.A = [-1.11 -1.12]; Sys.T1T2 = [1300 70];
Sys.AFrame = [0 5 0]*pi/180;

% 3. Параметры эксперимента
Exp.Field = 346.54; Exp.Sequence = '2pESEEM'; Exp.tau = 0.30546;
Exp.dt = 0.64;
% Exp.nPoints = length(time_exp);
Exp.nPoints = 1024;
Exp.ExciteWidth = 32; Exp.mwFreq = 9.700471;

% 4. Симуляция модели
[B, spec] = saffron(Sys, Exp);
spec = spec / max(spec); % Нормировка модели

% 4. Визуализация временных данных
figure(1);
subplot(2,1,1);
plot(time_exp, signal_exp, '-k', 'LineWidth', 1.5, 'DisplayName', 'Эксперимент');
hold on;
plot(B, spec, '-r', 'LineWidth', 1.5, 'DisplayName', 'Модель');
hold off;
xlabel('Время (\mus)'); ylabel('Интенсивность');
title('Сравнение эксперимента и модели');
legend; grid on; xlim([0 120]);

% 5. Фурье-анализ для эксперимента
Fs_exp = 1/(mean(diff(time_exp))); % Частота дискретизации
n_exp = length(signal_exp);
Y_exp = fft(signal_exp - mean(signal_exp));
P1_exp = abs(Y_exp(1:floor(n_exp/2)+1)/n_exp);
P1_exp(2:end-1) = 2P1_exp(2:end-1);
f_exp = (0:floor(n_exp/2))(Fs_exp/n_exp);

% 6. Фурье-анализ для модели
Fs_model = 1/(mean(diff(B)));
n_model = length(spec);
Y_model = fft(spec - mean(spec));
P1_model = abs(Y_model(1:floor(n_model/2)+1)/n_model);
P1_model(2:end-1) = 2P1_model(2:end-1);
f_model = (0:floor(n_model/2))(Fs_model/n_model);

% 7. Визуализация спектров
subplot(2,1,2);
plot(f_exp, P1_exp, '-k', 'LineWidth', 1.5, 'DisplayName', 'Эксперимент');
hold on;
plot(f_model, P1_model, '-r', 'LineWidth', 1.5, 'DisplayName', 'Модель');
hold off;
xlabel('Частота (МГц)'); ylabel('Амплитуда');
title('Спектры Фурье');
legend; grid on;
xlim([0 1]);