Hi Matt,
I'm the one who requested the merged reference channel.
If the data is ideal, of course only one reference scan is needed. But
there are two common ways it can be nonideal that are relevant:
1) The monochromator does not hold calibration; i.e. there is an
energy shift between scans
2) The reference channel is very noisy, perhaps because of an
inherently thick sample
If 1) is a significant problem and 2) is not, then it makes sense to
align the scans using the reference, at which point any reference scan
will do for determination of the chemical shift of the merged data
from the sample.
If 2) is a significant problem and 1) is not, then it makes sense to
merge the references along with the sample data, because that will
make it easier to determine the chemical shift.
If both problems are significant, then you've got a headache.
--Scott Calvin
Sarah Lawrence College
On Nov 19, 2009, at 10:26 AM, Carlo Segre wrote:
Hi Matt:
I agree. It is useful to have the reference channel from the first
of the merged data pulled over as reference for the merged data but
this actuallly only makes sense if the user first aligned using the
reference.
carlo
On Thu, 19 Nov 2009, Matt Newville wrote:
Is there ever a case where a merged reference channel is useful?
I thought the only possible use for a reference channel was for
comparing individual scans. That is, prior to merging.
--Matt
On Thu, Nov 19, 2009 at 6:45 AM, Zajac, Dariusz A.
<dariusz.za...@desy.de> wrote:
Dear Bruce, Dear All,
maybe it is a naïve question but I want to ask and to point this
problem...
Windows XP. Athena 0.8.059
Sc.Linux. Athena 0.8.060
I have a set of data with refernces (one sample, many scans). I
have marked sample's groups and do "merge marked data in mu(E)"
then I get merged data together with reference (2 groups: merge -
sample, and Ref merge - reference).
But...
...if I have marked reference sample's groups and do "merge" then
I get 2 groups: merge - which is merged data of reference, and Ref
merge - which is marged data of sample. Oposite to that I did in
first example!
Is any hidden idea, I can not see, why it should be that way? If
you don't know about that, can confuse and surprise...
cheers
darek
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Carlo U. Segre -- Professor of Physics
Associate Dean for Graduate Admissions, Graduate College
Illinois Institute of Technology
Voice: 312.567.3498 Fax: 312.567.3494
se...@iit.edu http://www.iit.edu/~segre
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