Alireza Rezaee Tazangi Fourier Transform is not used in UV-Visible spectroscopy because the data is already in the frequency domain, with absorbance measured directly at specific wavelengths. UV-Vis spectroscopy typically covers the UV region (200–400 nm) and the visible region (400–700 nm), where light absorption is measured as a function of wavelength. Unlike techniques like FTIR or NMR, which use time-domain data (e.g., interferograms) that require Fourier Transform to convert to frequency domain, UV-Vis provides direct intensity vs. wavelength data, making Fourier Transform unnecessary. The Heisenberg Uncertainty Principle applies more to time-energy relationships in certain contexts, but it does not affect UV-Vis spectroscopy.