• Becuase quadrupoles have very large coupling and are > spin 1/2, they represent a different type of NMR system. There is both a first order effect and a second order effect. The second order comes around becuase the couplings are so large (comperable to the magnetic field). The central transistion for quadrupoles is devoid of any anisontropy due to the first order, however, it is still effected by the second order. Below is the basic input file for the below figures. Simply changing the detection and initial density matrices will produce the below spectra. The second order effect is field dependant, and a loop over the Bfield variable will produce the 2D plot below as well.

# a basic quadrupole central transistion observation...you can
# simply change the spinning speed, detect, and ro to get the desired
# spectra shown below

spins{    
    #the global options
    numspin 1
    T 23Na 0
    Q 3e6 0 0
}

parameters{    

    powder{
         aveType zcw
        thetaStep 377
        phiStep 233
    }        

#the intergrator step size    
    maxtstep=1e-6

#number of 1D fid points    
    npts1D=512    

#sweepwidth
    sw=1000000
#the magnetic field
    Bfield=400e6
}


pulses{

# a 2D to loop over field strengths
    2D()
    
    BFpts=20
    BFstart=100e6
    BFend=700e6
    BFsteps=(BFend-BFstart)/BFpts

#set the spinning    
    wr=0
#set the rotor
    rotor=rad2deg*acos(1/sqrt(3))
#set the detection matrix

# the central transistion 'top' (+1)
    detect(Ip*Ip*Ip)

#loop of over the field strengths
    loop(i=0:BFpts-1)
        Bfield=BFstart

    #set the inital matrix
    # the central transistion 'bottom' (-1)
        ro(Im*Im*Im)

#no pulses nessesary    

    #collect the fid
        fid(i)
        BFstart=BFstart+BFsteps
    end
    savefidmatlab(bofields) #save as a matlab file
}

    

Here is the generated spectra, simply changeing the detection, ro, and the spinning speeds from the above input file.