clear;
clc;

load data_lines.mat

wl = data_lines(:,1);% unit nm
S = data_lines(:,2); % unit cm

P = 1; % unit mbar
R = 8.3144598e4; % unit cm3mbarK-1mol-1
T = 293; % unit K
N_a = 6.0221408577474747e23;
k = 1.3806488131313131313e-23; %unit JK-1
m = 26.04e-3/N_a; % unit kg

gas_density = P/R/T*N_a; % unit cm-3
c_const = 299792458; %unit mHz

N = max(size(wl));

wl_scan = linspace(1500,1550,30000); % unut nm

for n = 1:N
    
    wl_scan = wl_scan*1e-9;% unut m
    wl_line = wl(n)*1e-9; % unit m
    S_line = S(n)*1e-2; % unit m
    v_D = 2*360.1290167/wl_line; % unit Hz
    g_v = 2*sqrt(log(2)/pi)./v_D.*exp(-(2*sqrt(log(2))/v_D*c_const.*(1./wl_scan-1/wl_line)).^2); % unit Hz
    T = exp(-gas_density*1e6*S_line*c_const.*g_v);
    
    wl_scan = wl_scan*1e9;
    plot(wl_scan,T,'r','Linewidth',2);
    hold on;
    
end
    
xlabel('Wavelength [nm]');
ylabel('Spectral transmittance per meter');
title('1 mbar Acetylene gas absorption');