FT-IR spectral analysis

Hey,

I'm quite new to Matlab and would like some help!

I have FT-IR spectra that need to be analyzed. What I want to do it, to do a baseline correction on the spectra. How do I go about doing that? I also want to cut out spectra with intensities lower than a specific threshold for e.g. 0.1 or 0.2.

Is there a possible way to see these spectra individually on MATLAB somehow?

After all the pre-processing steps I would like to apply a cluster analysis such as VCA or a PCA.

Hope this clarifies my problem.

Answer 1

[Wayne King]

When you say baseline correction, you'll have to be more specific about what you mean. The magnitude or magnitude-squared of the Fourier transform has a lower bound of 0. So are you saying that your spectra have linear drifts that need to be corrected.

You can use detrend() to remove the best linear fit.

Or perhaps you mean you want to place all spectra on the same scale by dividing by the maximum value so that everything peaks at 1. That you can easily do by the following assuming that xdft is your spectrum:

xdft = xdft./max(xdft);

Can you attach one data file to clarify what you mean?

Answer 2

[Kokila]

The files are too large to attach here but I've attached an image that might describe what I would like to do. There are peaks that I'm interested in and they sit on some sort of 'background' and to crudely put it I want to pull these more towards the x-axis (wavenumber) so to speak.

No I don't mean normalizing intensities from 0- 1, but thank you for that hint.

Cheers!

[Wayne King]

I don't see the image attached.