Our NMR apparatus is an hybridization of
Oxford
instruments TeslatronH magnet,
Oxford
instruments continuous flow cryostat, a
TECMAG
spectrometer, and a home built head. All systems are controled by a MAC
and experimental parameter such as magnetic field, temperature, frequency
etc. can be modified automatically.
The construction of this NMR laboratory was funded by:
Instrument Scientist:
Magnet
The leads of the magnets are permanently connected and the field can
be swept from zero to 9T in 1G steps. The homogeneity is 2ppm in 1cm3
and no shimming coils are installed.
A. Keren is acting as if he is doing something.
Cryostat
The Oxford instruments
continuous flow cryostat (CF1200 daynamic) allows a working temperature
ranging from 1.6 to 450K, and a 62mm sample space diameter.
G. Bazalitsky transferring N2, Z. Salman is analyzing
data and A. Keren is looking for a signal.
Spectrometer
The spectrometer is single channel. It is constructed from TECMAG
NMRKit-II as a transmitter and receiver, and LIBRA as a pulse programmer
and ADC. It uses a PTS-310 frequency synthesizer, and AMT 1KW power supply.
Currently we are capable of working between 6-220 MHz due to the AMT frequency
range.
Z. Salman and G. Bazalitsky working and working and working and
working.
Head
The head is made of series-parallel tank circuit using Cylindrical
Teflon capacitors. The capacitance can be varied from the top of the cryostat.
In order to load a sample the head must be removed from the cryostat.
Z. Salman is changing sample.
Origin
Origin 7.0
The experiment's data are imported into Origin worksheets and brought home
for analysis. We have developed specialized macros under Origin for NMR data
analysis.
Programer:
NMR Publications:
-
A. Keren, Spin echo decay in a stochastic field environment,
Phys.
Rev. B 60, 9279 (1999).
Abstract:
We derive a general formalism with
which it is possible to obtain the time t dependence
of the echo size for a spin in a tochastic field environment. Our model
is based on ''strong collisions''. We examine in detail two examples. In
the first one the field distribution has a finite second moment, and in
the second one (a Lorentzian) it does not. We find that the echo decay
in the first case is exponential in t3
as t->0, and in the second case can be approximated
by the phenomenological expression exp (-[2t/T2]b)
with 1<b <2; in the t->0
limit b =2. In addition, only the first case
shows a T2 minimum effect.
The paper in PDF
format (73 kB).
