Hi,
my personal preference would be for option (2) because
(a) in many situations one will be interested in looking at a splitting
in only one dimension and so it is nice if the the other dims are still
in ppm
(b) in most cases people are likely to be looking at only one spectrum
at a time or at spectra which were recorded on the same machine, i.e.
with the same sf. So choosing an sf for the conversion should be
straightforward - good rules might be to choose the 'top' spectrum -
i.e. the first in the Spectrum toolbar which is on (or the first one
full stop, if none are on)
(c) I probably fall into the 'love the fixed aspect ratio' category
I wonder whether you have had any thoughts about what this does to mouse
lines, marks and rulers? It would be useful to have the choice of having
them function in Hz or ppm for the axis which is in Hz - the same sf as
above could be used for the conversion. Alternatively, for some double
quantum spectra it might be useful to have the mouse doing something
more fancy...
Vicky
Wayne Boucher wrote:
> Hello,
>
> I am looking now at this Hz issue. Tim and I sort of decided that
> what made most sense was now to worry about the different spectra
> having different sf and just doing the conversion for each of them as
> each individually should be done.
>
> Then we thought that it made sense to allow different choices of
> ppm/Hz for each axis (so x, y, and orthogonal). This brings up the
> second problem though, and that is aspect ratio. Currently Analysis
> has a fixed aspect ratio between x and y. But if x is ppm and y is Hz
> what does the aspect ratio mean? You (in effect) need an sf to do the
> conversion, which (in effect) means you need a spectra. But a window
> might have no spectra in it or a window might have spectra with
> different sf in it (note, the diagonal would look wonky for some of
> the spectra in this case).
>
> There are a couple of options, so I'd be interested in hearing
> people's opinions.
>
> (1) Insist that x and y are both ppm or both Hz. Is there anyone for
> whom this sounds like a serious restriction on what you would like to
> do with Hz? (Well, I myself can imagine that you have splittings only
> in one dimension so want ppm in the other dimension. That is what
> worries me.)
>
> (2) Allow x and y to have ppm/Hz independent of each other. Pick the
> "first" spectrum (if it exists) in the window to determine sf. Or
> pick the maximum sf. Or some other such rule.
>
> (3) Allow x and y to have ppm/Hz independent of each other. Forget
> about forcing the y and x axes to have a fixed aspect ratio. This is
> a pretty dramatic change from the current way of doing things so
> although it solves this immediate problem in perhaps the best way, it
> should only be done with some forethought. So I guess the question
> here is how many people love the fixed aspect ratio and how many
> people hate it and how many people don't mind one way or the other.
>
> Note that if we allow x and y to have ppm/Hz independent of each other
> then when the user (say) has x and y in ppm and switches x to Hz then
> the x axis region ought to change but that definitely requires some sf
> to do so. In (2) we have a preferred sf but in (3) we would
> effectively have to have one for this specific operation. (But it's
> not the end of the world if the new region isn't quite what was
> intended, as long as it's in the correct ballpark.)
>
> Wayne
>
> On Thu, 27 Aug 2009, Marco Roeben wrote:
>
>> Hi Wayne,
>>
>>> Slipped through the cracks! So currently there is no way to do Hz. Is
>>> this for splitting measurements? (Because we are going to add coupling
>>> constant functionality.) Or is it that you just want to see Hz
>>> instead of
>>> ppm (which is more difficult because different spectra might have
>>> different sf)?
>>
>> I need both. I use ccpnmr also for the analysis of small molecules and
>> therefore I have for example an 2D-INADEQUATE experiment. This has in
>> F1 the
>> double quantum frequency of the two coupled nuclei. I'm also working
>> towards
>> the analysis of some cross correlated relaxation experiments and here
>> I also
>> have double or zero quantum coherence's. To see If everything has
>> worked out I
>> need to work with Hz instead of ppm. At the moment I'm always switching
>> between Topspin and ccpnmr.
>>
>> I also would like to analyze coupling constants for RDCs.
>>
>>
>> best regards
>> Marco
>>
>> --
>> Dipl. Chem. Marco Röben
>> Leibniz-Institut für Molekulare Pharmakologie (FMP)
>> dep.: Solution NMR
>> Robert-Rössle-Str. 10
>> D-13125 Berlin
>> +49-30-94793224 (phone)
>> +49-030-94793169 (fax)
>>
--
*********************************************************
Dr. Victoria A. Higman
Leibniz-Institut fuer Molekulare Pharmakologie (FMP)
NMR-Supported Structural Biology
Robert-Roessle-Str. 10
13125 Berlin
Germany
and
School of Chemistry
University of Bristol
Bristol BS8 1TS
United Kingdom
Phone: +44-117-95-46325
E-mail: [log in to unmask] (or [log in to unmask])
http://www.protein-nmr.org.uk
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