wq = 63460.; (* quadrupole frequency *)
rho0 = -H0; (* equilibrium state *)

(* double quantum pulse *)
wRF = (2*wL - wq)/2; TP = 0.5*10^-3; w1 = 15172;
H1 = HRF[spin]; rho1 = Pulse[rho0];

(* single quantum pulse *)
wRF = wL + wq; TP = (0.5*10^-3)/2;
w1 = 7250; H1 = HRF[spin]; rho2 = Pulse[rho1];

(* magnetic field gradient *)
G = (250*10^-4); TG = 1.0*10^-3; rho2 = Grad[rho1];

(* detection pulse *)
wRF = wL; TP = 1.0*10^-6; w1 = (Pi/20)/TP; H1 = HRF[spin]; rho3 = Pulse[rho2];