Scale Factor Dependencies in Quantum Dipole Coupled Lee-Goldburg Cross-Polarization Experiments

Abstract

Lee-Goldburg cross polarization is used in many NMR experiments to determine internuclear distances. Distances calculated from frequency peaks in the dipolar coupled dimension are subject to scale factors. Experimentally determined scale factors can differ significantly from the theoreticalyy useful value described in the literature. In this work, simulations using SPINEVOLUTION explore effects of varying experimental parameters of frequency offset and cross polarization powers on $^{15}$N-H systems. Experimental data is used to corroborate the simulation. The scale factor is shown not only to depend on the offset frequency but also the cross polarization powers of the observed nucleus. Scale factors greater than one are shown to be possible in simulated data, though such factors obscure the determination of internuclear distances.