I don't know if I have a problem or not running
a ROESY expt on a Bruker machine. I am looking at
a small peptide in water, using a simple cw pulse
for the 200 ms spin-lock [90 deg ~ 120us for the SL]. When
I look at the 1st FID there is a large offset dependence
in the peak intensity. This dependence diminishes on
subsequent FID's, and the resulting spectrum appears OK.
My question is: is this normal? and what would be causing
this resonance dependence. I assume a simple Hartmann-Hahn
match would result in a poor qualilty final spectrum, but this
is not the case. Thanks in advance.
Cheers,
Michael Jablonsky
NMR Core Facility
U of AL @ Birmingham