Slow passage detection - calculates spectrum values at the user specified frequency positions using the Fourier transform of the Liouville - von Neumann equation. The biggest advantage over the fid+fft style detection is easy parallelization and the possibility of getting spectrum values at specific frequencies without recalculating the entire free induction decay.
parameters.sweep vector with two elements giving the spectrum frequency extents in Hz parameters.npoints number of points in the spectrum parameters.rho0 initial state parameters.coil detection state H - Hamiltonian matrix, received from context function R - relaxation superoperator, received from context function K - kinetics superoperator, received from context function
spectrum - the spectrum of the system with the specified starting state detected on the specified coil state within the frequency interval requested
The 14N overtone MAS spectrum of glycine recorded using this method (examples/nmr_overtone/mas_glycine_1.m) appears below. FID+FFT simulation in this system is much slower.
Relaxation must be present in the system dynamics, or the matrix inversion operation would fail to converge. The relaxation matrix R should *not* be thermalized.
Version 2.3, authors: Ilya Kuprov