What's new in 2007
December 2, 2007:
Two approaches, coherence filtering and phase cycling, for simulating the variations of echo and/or antiecho amplitudes versus a pulse duration in three-pulse MQMAS sequences:
whose third pulses are a soft or weak amplitude pulse are tested with SIMPSON1.1.1 Tcl scripts.
An excellent agreement is obtained with these two approaches when more coherence transfer pathways are considered. The coherence filtering approach provides the results in much shorter simulation time than the phase cycling approach.
October 30, 2007:
The winding numbers for cogwheel phase cycling of three-pulse split-t1 3QMAS sequence applied to a spin I = 3/2 system have been determined using two web tools:
- XML (eXtensible Markup Language) for modelling the pulse sequence and the associated phase cycling;
- XSLT (eXtensible Stylesheet Language Transformation) for numerical search of these winding numbers.
These web pages require the installation of mathML plugin.
SIMPSON1.1.1 simulation of the antiecho amplitude using these winding numbers and that using coherence filtering method agree with an accuracy of 10-8.
September 4, 2007:
Procedure for allowing Internet Explorer 6+ to display scalable vector graphics (SVG) in web pages coded with SVG 1.1 markup language is described. However, vector graphics cannot be printed within IE.
Our first web page coded with SVG1.1 is that of the quadrupole interaction.
August 1, 2007:
Procedure for allowing web browsers (Mozilla/Firefox, Internet Explorer 6+, and Opera 9+) to display mathematical content in web pages coded with mathML 2.0 markup language is described.
Our first web page coded with mathML is that of the quadrupole interaction.
July 1, 2007:
Phase cycling procedures for shifted-echo MQMAS sequences are analyzed with SIMPSON1.1.1 Tcl scripts using two approaches: (i) filtering the desired coherences associated with the coherence transfer pathway diagram, and (ii) explicit phase cycling the pulses and the receiver in a simulated experiment.
June 19, 2007:
Phase cycling procedures for two-pulse MQMAS sequences and z-filter MQMAS sequences are analyzed with SIMPSON1.1.1 Tcl scripts using two approaches: (i) filtering the desired coherences associated with the coherence transfer pathway diagram, and (ii) explicit phase cycling the pulses and the receiver in a simulated experiment.
For two-pulse 3Q-MAS experiments, these two approaches provide the same simulation data about echo and/or antiecho amplitudes.
For three-pulse z-filter 3Q-MAS sequences, these two approaches may not generate the same simulation data for echo and/or antiecho amplitude, depending on the experiment. A disagreement means that the phase cycling procedure does not properly describe the coherence transfer pathway diagram.
When a phase cycling approach generates the same echo and/or antiecho amplitudes as the filtering approach, the phase cycling procedure is valid whatever the nature (strong pulse or not) of the third pulse.
March 14, 2007:
A modification of the AU program xfshear is proposed for shearing 2-dimensional MQMAS spectrum acquired with the SPAM echo/antiecho pulse program.
February 8, 2007:
The definition of echo and antiecho in MQMAS experiments are provided.
The AU program xfshear for shearing MQMAS spectra has been commented.
February 6, 2007:
Deuterium-2 and Nitrogen-14, two spin-1 nucleus references are included.
January 4, 2007:
The pulse programs of Fernandez and coworkers about multiplex SPAM MQMAS and multiplex z-filter MQMAS for Bruker spectrometers are described.