On 9/29/2009 2:51:57 PM, lpoulo wrote:
>Is this something ad hoc, need only for
>this particular analysis, or, as I
>suspect, are you looking for a more
>general technique that you can use of
>other data sets?
It would be applied to several thousand spectra, yes.
>Do you need to get the ILS params from
>the data itself, or do you have a
>separate, independent model or test data
>that can be used for the corrections?
What I posted is the separate test data 🙂
The natural peak width in what I posted is, to all intents and purposes, zero. So the data represents the ILS at different wavelengths.
The actual data that the deconvolution will be applied to has broader peaks than this. My first step would be to deconvolve this data though, so that the skew is removed and the peaks all look like the ones around 950.
>Are the isolated peaks usable to extract
>params?
Yes, that was my intent when I acquired this data.
I expect the symmetric part of the ILS to be very close to Gaussian (so a Gaussian should fit the single peaks around 950, but I haven't tried it yet). The asymmetry is going to be a guessing game, but I would try to model it with some sort of asymmetric Gaussian (even though that is a contradiction in terms!)
>I would guess that this is a fairly
>common problem, so I'm surprised that
>there are no standard tools to deal with
>it.
That was exactly my thinking. I didn't know of such a tool, and the fact that I had never heard of one surprised a little bit. But I figured that if I searched the web I would find something. When I couldn't find something I was more surprised, but figured that I must just be searching for the wrong terms, because I didn't know what it was called. So then I posted the question here.
>Unfortunately, this will likely gnaw
>at me and I'll work on it(slowly) in
>spite of your admonition.
If it makes you feel any better, it's bugging me too. And now my client has found an alternative solution (using a more expensive instrument that doesn't have the problem in the first place), so I actually also have no better reason to work on it than curiosity! I'll spend some time on it over the next few days I expect, and will post anything useful.
Richard