I am writing an application that should allow to view and manipulate spectra (Ra

Question

I am writing an application that should allow to view and manipulate spectra (Raman).

I am only given one normal spectrum consisting of 1024 coordinate points. Plus I have a background spectrum that is supposed to be subtracted from the first spectrum.

f.e.:

The first point in spectrum_1 is: -55.988 , 9373 The according point in background spectrum: -55.988 , 9382. After subtracting the two in a third-party software, the first point of the resulting spectrum is: -55.988 , -641.968

So I asked myself how this is calculated. According to the Documentation of this software, it is using the following formula:

result spectrum(n) = multiple component spectrum(n)

Explanation / Answer

Background subtraction of Raman spectra is as simple as regular subtraction (assuming that both spectra are measured in the same way, same wavelength step size etc.)

Your third-party software does something else. The formula from the Documentation looks like subtraction of different spectral contributions. Suppose that you have, say, water and ethanol - two components. Observed multi component Raman spectrum will be a linear combination of water and ethanol Raman spectra. If you subtract spectra of these compounds (measured separately) from your total spectrum, you should get a straight line or a Raman spectrum of some other substances that you might have in the mixture.

Factor1,2 are just proportionality coefficients that you would need to adjust to match a sum of individual spectra to the total spectrum. I suppose that (n) here means that you perform this operation for every data point in a loop.

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