Exact results on spin dynamics and multiple quantum NMR dynamics in alternating spin- 1/ 2 chains with XY-Hamiltonian at high temperatures
E. B. Fel'dman, M. G. Rudavets
Institute of Problems of Chemical Physics RAS, 142432 Chernogolovka, Moscow Region, Russia
PACS: 05.30.-d, 76.20.+q
Abstract
We extend the picture of a transfer
of nuclear spin-1/2
polarization along a
homogeneous one-dimensional chain with the
XY-Hamiltonian
to the inhomogeneous chain with alternating nearest neighbour
couplings and alternating Larmor frequencies. To this end, we
calculate exactly the spectrum of the spin-1/2 XY-Hamiltonian
of the alternating chain with an odd number of sites.
The exact spectrum of the XY-Hamiltonian is also applied to study
the multiple quantum (MQ) NMR dynamics of the alternating spin-1/2
chain. MQ NMR spectra are shown to have the MQ coherences of zero and
second orders just as in the case of a homogeneous chain. The intensities of
the MQ coherences are calculated.