Johannes,
You have two possibilities: first, you need to determine the 180 degree
pulse using a double resonance experiments and an appropriate sample on
the 3rd channel.
The you bypass the preamplifier module, setup the redor experiment and
measure on an easy sample a redor without dephasing ( no pulses on f3)
the number of rotor periods should be chosen such, that with dephasing
pulses you would expect a strongly attenuated signal. Then you switch
on the 3rd channel use the power level -0.5 - -1dB ( about 0.5 to 1 dB
less power - to account for HPPR losses), use the measured pulse widths
for the 180 degree pulse and paropt pl3 or whatever you have on channel
3 in 0.1 - 0.2 db steps and look for the signal minimum - maximum
attenuation. Then you have the correct PI pulse.
Method 2 is: Use the Bloch-Siegert shift for measuring B1 field of a
channel by measuring the dephasing of a spin echo signal. In detail, you
make a spin echo experiment, e.g. on glycine CP-tau - Pi_pulse - tau
-acquisition, you ft and phase the spectrum. Then you apply a pulse
with a certain power level for a time T prior to the echo on channel 3
during the spin echo experiment:
Reference experiment:
F2 e.g. 1H p90- CP - Decouple
F1 e.g. 13C CP ---- tau ---- PI ---- tau ---- acqu
F3 e.g. 2H -----------------------------------------------------
(no pulses)
Shift experiment :
F2 e.g. 1H p90- CP - Decouple
F1 e.g. 13C CP ---- tau ---- PI ---- tau ---- acqu
F3 e.g. 2H ------------PulseT------------------------------
one pulse with duration T before the echo pi pulse
you measure the additional phase correction you need for a correctly
phased spectrum. From this phase difference you can calculate the B1
field in channel 3. Terry Gullion suggested this method some time ago.
Please contact me if you need further instructions.
Jochem
_____________________________
Jochem Struppe PhD
Bruker BioSpin Corp.
NMR Applications
15 Fortune Dr
Billerica, MA 01821
Telephone (978) 667 9580 ext. 5113
Mobile (978) 973 3547
Fax (978) 667 2955
Jochem.Struppe_at_bruker-biospin.com
-----Original Message-----
> From: Donna Baldisseri [mailto:donna.baldisseri_at_bruker-biospin.com]
> Sent: Monday, February 23, 2004 11:25 AM
> To: jos_at_bruker-biospin.com
> Subject: [Fwd: REDOR on Bruker]
-------- Original Message --------
> Subject: REDOR on Bruker
> Date: Fri, 20 Feb 2004 17:17:02 -0500
> From: "Johannes Leisen" <mailto:johannes.leisen_at_ptfe.gatech.edu> <johannes.leisen_at_ptfe.gatech.edu>
> To: <mailto:ammrl_at_ammrl.org> <ammrl_at_ammrl.org>
Dear All,
We are in the process of setting up REDOR-type experiments on our Bruker
DSX400 solid state NMR spectrometer.
We have a somewhat minimal configuration, which Bruker assured us would
allow triple resonance experiments:
- Triple Resonance Probe
- 3 FCU units
- 2 BLAX300 and 1 BLAH300 transmitters
- the old high power cabinet with two 1 kW tube amplifiers for 1H and X.
We have only two preamplifier channels, which makes all setup procedures
of the third channel quite
complicated. Does anyone have a similar configuration than we do? What
is the setup procedure to determine the
pi-pulse length for this channel?
Thank you,
Hanno
********************************************************
Dr. Johannes Leisen
Research Scientist II
Georgia Institute of Technology
School of Polymer, Textile & Fiber Engineering
Atlanta/GA 30332-0295
phone: (404) 894-9241; FAX (404) 894-9766
e-mail: <mailto:johannes.leisen_at_ptfe.gatech.edu>
johannes.leisen_at_ptfe.gatech.edu
--
Donna Baldisseri, Ph.D.
Senior Applications Scientist
donna.baldisseri_at_bruker-biospin.com
Application Support Hotline
Phone: (978) 667-9580, Ext. 5444
FAX: (978) 667-2955
email: applab_at_nmr.bruker.com
Bruker BioSpin Corp.
NMR Division
15 Fortune Dr., Manning Park
Billerica, MA 01821 USA
www.bruker-biospin.com
Received on Mon Feb 23 2004 - 12:04:29 MST