Studies on Spectral, Absorbance and Transmittance Properties of Indian Automobile Paint Samples using UV-Vis Microspectrometer and its Forensic Significance

Paint samples are considered as most crucial types of trace evidence come across hit-and-run and vehicular accident cases. Particularly in establishing links between suspected vehicles and crime scenes, the forensic analysis and comparison of such paint samples play a vital role. The present work focuses on the spectral (S), absorbance (A), and transmittance (T) characteristic analysis of paint samples using a UV-vis microspectrometer instrument. The spectral characteristics of the paint samples were carried out in the wavelength range of 380–800nm to assess their optical properties. The absorbance spectra of the paint sample described distinct peaks responsible for the presence of particular pigments and binder materials. APF-4 displays the highest initial absorbance at approximately 0.56% at 400 nm, which gradually decreases toward the higher wavelengths, suggesting a high concentration of pigments absorbing in the blue region of the spectrum. Simultaneously, the transmittance characteristic of the samples illustrated variation across different paint types, which can aid in distinguishing similar-looking paints of different origins. . APF-3 exhibits the highest transmittance overall, reaching values exceeding 120% at wavelengths above 600 nm. The findings highlight the usefulness of UV-vis microspectroscopy as a non-destructive, rapid, and reliable technique for characterizing automobile paint samples.