Dear AMMRLs,
I like to share this summary information of 77Se and 125Te solid state NMR
with you. Thanks to those who sent me helpful messages: Sophia Hayes, Guy
Bernard, Glenn Penner, Bob Taylor, Tanja Pietraß, Jim Frye, and David
Apperley.
References: J. Magn. Reson. V. 68, p. 172 (1986) and J. Phys.: Condens.
Matter, 12(2000), 2579-2595
Spectrometer: Any, but with solid capabilities
Probe: Doty MAS probe or the others
Rotor: 5mm or 7mm ZrO2
Standard: Ammonium selenate, (NH4)2SeO4, 1040 ppm, relatively to SeMe2, 0
ppm.
Telluric acid, H2TeO4.2H2O, two peaks at 692.2 and 695.7 (Taylor) / 685.5
(Apperley) relatively to TeMe2.
Pulse sequence: One pulse, or Cross Polarization. Note that Se77 or Te125
relaxation time is relatively long, e.g. Telluric acid T1 is about 350
seconds. If your sample has proton around, you’d better use CP. The recycle
delay time is about 1 – 10 s for Se77, 120 s for Te125, and contact time is
about 1 – 4 ms.
Regards,
Yuyang
Yuyang Wu, Ph.D.
NMR Specialist
ASL, Chemistry
Northwestern U.
2145 Sheridan Rd.
Evanston, IL 60208
Phone: 847-491-7080
Fax: 847-491-7713
Received on Fri Jun 07 2002 - 17:04:20 MST