Dear All,
If it's a CPMAS probe (i.e., double-resonance), use KBr.
If the probe tunes only to 1H or thereabouts, an excellent
sample is barium chlorate hydrate. Spin about 4 or 5 kHz.
Measure with a single pulse, once per 5 seconds. Adjust to get
the longest echo train. Alternatively, look at the spectrum and
adjust to get the narrowest peaks.
Warnings:
Barium chlorate hydrate is toxic, to some extent. It is a
strong oxidizer, so do not mix it with other sample materials
(or else you may create a risk of fire or explosion).
Other hydrated salts might work, but few are as sensitive to
the magic angle setting. I've heard that fluoroapatite
(observing 19F) might be a good one, but I haven't tried it.
--
Tony Bielecki
Senior Applications Scientist (Solid State NMR)
Bruker Instruments, 44 Manning Road, Billerica, MA 01821
Telephone 978-667-9580, ext 145 Facsimile 978-667-2955
E-mail: tony.bielecki_at_nmr.bruker.com
Received on Fri May 19 2000 - 18:40:26 MST