function  integrand_O_O2
% Plot the integrand for the equilibrium rate for O-O2 dissociation
% for three temperatures, 6000K, 6100K and 6300K. Fig, 
clc
ymax=34;
temp=6000; kt=0.8617e-04*temp; yzero=14.5/kt; y=linspace(yzero,ymax,100)
e=kt*y; [sig]=sigma_O_O2(e); f=1e12*y.*exp(-y).*sig
plot(y,f,'-k','linewidth',1.2)
hold on
temp=6100; kt=0.8617e-04*temp; yzero=14.5/kt; y=linspace(yzero,ymax,100)
e=kt*y; [sig]=sigma_O_O2(e); f=1e12*y.*exp(-y).*sig
plot(y,f,'-k','linewidth',1.2)
hold on
temp=6200; kt=0.8617e-04*temp; yzero=14.5/kt; y=linspace(yzero,ymax,100)
e=kt*y; [sig]=sigma_O_O2(e); f=1e12*y.*exp(-y).*sig
plot(y,f,'-k','linewidth',1.2)
% Format the graph
axis([27 34 0 1.2])
set(gca,'FontSize',20)
set(gca,'Ytick',[0:.2:1.2],'linewidth',1.6)
set(gca,'Xtick',[27:1:34],'linewidth',1.6)
xlabel('$y=E/k_BT$','Interpreter','LaTex','FontSize',24)
ylabel('$ye^{-y}\sigma(yk_BT) \times 10^{12}$','Interpreter','LaTex','FontSize',24)
str1 = {'$T =[6200K, 6100K, 6000K]$'};
text(28.7,1.1,str1,'Interpreter','Latex','Fontsize',14)
hold off
% Dissociative reactive cross section for O-O_2
function [sig]=sigma_O_O2(e)
n=length(e);
for i=1:n
sig(i)=4.51*(e(i)-14.5)^1.03/(0.21+e(i)^1.31);
end