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 Fitting of multi-component optical spectra		  New Topic  Reply to Topic
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hergen

USA
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Posted - 08/02/2022 :  5:18:49 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
I want to fit an optical absorption spectrum (intensity vs. wavelength). Multiple chemicals (each with its own characteristic absorption spectrum) but unknown concentrations, are contributing to the measured spectrum. I’m trying to determine the concentrations of the individual chemicals.

In the simplest case, I have the reference spectra of two chemicals and the measured spectrum:

Col(A): Wavelength
Col(B): Reference spectrum for chemical 1.
Col(C): Reference spectrum for chemical 2.
Col(D): Measured spectrum.

Each column could contain 1000s of data point.

Col(D) = concentration 1 * Col(B) + concentration 2 * Col(C)

How can I do that in OriginPro?

Thank you.

aplotnikov

Germany
169 Posts
Posted - 08/03/2022 :  03:23:22 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Use reference spectra as X-columns (X1, X2) and the measured spectra as Y (in particular - Y2).
Create an NL fit function:
y=c1*x1+c2*x2 (I would suggest to add background as well: y=c1*x1+c2*x2+y0), where x1 and x2 - independent variables and c1,c2(,y0) - parameters to fit.
Now if you select all three columns and start non-linear fitting session for the selected data with the created function the dataset names should be determined automatically. Set boundaries for parameters, etc. if necessary. Start fitting.
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Echo_Chu

China
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Posted - 08/03/2022 :  03:32:42 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
The app should work as you want

https://www.originlab.com/fileExchange/details.aspx?fid=406

Echo
OriginLab Technical Support
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hergen

USA
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Posted - 08/03/2022 :  1:29:25 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Thank you.
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