Inversion Recovery/T1 Experiment

Armando Herbelin (armando@janice.cc.wwu.edu)
Fri, 4 Feb 1994 10:56:11 -0800 (PST)

I'm working on an inversion recovery experiment for determination of T1
for ferrocene. Since the relaxation delay needs to be ~ 5* T1, the
experiment takes about 50 minutes to collect 10 data points. To reduce
T1, we are currently trying to use Cr(acac)3 which brings T1 down to about
5-10 ms depending on how much you add - or at least I hope so.

Anyway, while working on this experiment, I noticed a problem: When the
FID is being collected (NS=8), on about the third pulse, the data cancels
out a large portion of the FID's intensity and shape. I'm not sure what
causes it but my first impression is that the inversion/recovery pulse
sequence is not timed correctly, resulting in a phase difference and the
cancellation.

Does anyone have an idea what is up? I've tried several samples, with and
with-out ferrocene and get the same result. Also, my T1 plots do not look
to great, with a huge variance in their result.

I should note that while I have become pretty good at collecting simple
spectra and managing file systems, my quantum is pretty rusty, especially
when it comes to pulse sequences.

Thanks in advance,

Armando the <partially> great.
armando@henson.cc.wwu.edu