## Quadrupolar Sideband Manifold

**quad1_full**

*********************************************** ******* Full sideband manifold ********* ****** The System ***************************** spectrometer(MHz) 500 spinning_freq(kHz) 10 channels X(200 3/2) nuclei X atomic_coords * cs_isotropic * csa_parameters * j_coupling * quadrupole 1 1000 0.25 0 0 0 dip_switchboard * csa_switchboard * exchange_nuclei * bond_len_nuclei * bond_ang_nuclei * tors_ang_nuclei * groups_nuclei * ******* Pulse Sequence ************************ CHN 1 timing(usec) (0)128 power(kHz) 0 phase(deg) 0 freq_offs(kHz) 0 ****** Variables ******************************* pulse_1_1_1=1000/spinning_freq/128 pdata_re(64)=eval(0,pdata_re) ******* Options ******************************** rho0 I1x observables I1p EulerAngles lebind65o n_gamma 128 line_broaden(Hz) * zerofill * FFT_dimensions 1 options -re -sz7 -fft1 -ws ************************************************ COMMENTS: -- This computes the intensities of the spinning sidebands. The centerband (which is very intense) is "erased" in the Variables section. This, of course, is not necessary, but illustrates possible uses of the pre- and post-processing variables). -- -sz7 option sets the number of frequency bins for collecting the spectral intensities during the g-COMPUTE algorithm to 128. The spacing between the centers of the bins is made to coincide with the spinning frequency by choosing the dwell time equal to the 1/128-th of the rotor period, which makes the spectral width equal to 128 spinning frequencies. With this choice, each sideband, although broadened by the the 2nd-order quadruplar interaction, is collected in just one bin. The total intensity collected in that bin (i.e. the intensity of the point in the spectrum on the output) then reflects the total sideband intensity over all orientations in the powder. -- Since the 2nd-order quadruplar interactions, although present in the Hamiltonian, do not affect the total intensities of the sidebands, exactly the same spectrum can be obtained with the -quad1 option. -- The -ws option is specified to disable the interpolation of the spectal frequencies (as functions of the orientation), which is useless in this case since the frequencies are made orientation-independent by the way they are binned. Enabling interpolation would produce the same result, but it would take a bit longer to compute. -- The spectum on the output is obtained by first computing the FID from the binned spectrum produced by the g-COMPUTE algorithm (by computing the inverse FT of that spectrum), which is then Fourier transformed back again. The -fft1 option ensures that the first point of the FID is not modified, so that the spectum on the output coincides with the original binned spectrum. -- This kind of input file is easily remade into a sideband fitting task (see csa-sb-fitting example).