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Found a following statement in the pulse program called What does this do - specifically last bit of the second part - The first one - I understand shaped pulse at power Looks like Is I've also seen other notation which seems to be more understandable to me: The parentheses contain all the parameters used by the shaped pulse. The first variant does not use parentheses - so I wonder - what is the meaning of that? Thanks! |
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p12:sp2:f1 ph2:r statement tells you that you have to adjust the PHCOR2 parameter. This is basically the phase difference between pulse p12 and the pulse that was applied prior to this shape pulse in the channel f1. -Ilango. Thanks. What I am confused about is why ph2:r part is after the pulse statement. Will this be legal/equivalent -> (p12:sp2 ph2:r):f1 ? - Evgeny Fadeev (Jul 16 '10 at 08:04) That is correct. I would take it as the default f1 channel if nothing is specifically mentioned. I checked the pulse programs supplied by Bruker. Only few programs (selcogp, seldigp, selgpse etc) uses that syntax. May be outdated now, I guess. -Ilango. -Ilango. - Ilango (Jul 16 '10 at 09:23) p12:sp2:f1 ph2:r can only be used if it stands alone on a line. The command (p12:sp2 ph2:r):f1 is equivalent but must be used if there are other commands on the same line. - Clemens Anklin (Aug 08 '10 at 06:18) |
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The :r statement seens to be a random phase of the pulse based in ph2 = 0 0 1 1 2 2 3 3. I´m not sure because this statement is used to be in pulse, not in phase (e.g. p1:r - pulse duration with random variation). |
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An additional comment about the use of the :r syntax: the phase of pulses will depend on the attenuation level, to a greater or lesser extent. For selective 1D experiments, the difference in attenuation between the hard pulse and shaped pulse is very large, so sometimes it could be beneficial to adjust the phase of the shaped pulse to correct for this. The most critical case would be something like a 1D shaped-pulse WATERGATE experiment, where any phase error will cause imperfect solvent suppression. On modern Bruker instruments, the amplifier output may be linearised by the software - the CORTAB procedure. In this the output pulse amplitude and phase are measured as a function of input power, to determine the deviation from perfect linearity, and this result is stored on disk. When you run an experiment on a nucleus which has a CORTAB available, a correction factor is then applied to the amplitude and phase, as pulses are generated. In general this is not done for all nuclei, but for proton (and carbon, nitrogen) on recent instruments is likely to be present. You can see if you have a CORTAB by looking at the routing with |
