The Statistics and Machine Learning Toolbox is essential for research. You might also need the Signal Processing Toolbox, depending on what you’re doing. It is likely worth getting for the findpeaks function, as well as filter design and filtering, depending on the nature of the signals you’re processing.
When I looked up Fourier transform infrared spectroscopy those were the only Toolboxes that appeared applicable. It’s not possible to anticipate the direction your research will go, so others may be appropriate.
