Effective Separation of Raman Signals from Fluorescence Interference in Undyed and Dyed Textiles Using Shifted Excitation Raman Difference Spectroscopy (SERDS)

Abstract

Textiles are an integral part of our everyday lives, e.g., in the form of clothing and furniture. Consequently, their analysis is of great interest in a wide range of application areas including quality control, textile recycling, forensics, and cultural heritage studies. Optical methods offer a large potential for rapid and nondestructive textile inspection. Raman spectroscopy is a particularly promising candidate for this task as it delivers a fingerprint of the sample on the molecular level, thus giving insights into the textile material composition. Currently, a major challenge preventing the widespread use of Raman spectroscopy for textile analysis is the strong fluorescence background originating from additives, e.g., dyes or the fiber material itself. To address this main limitation, this study applies shifted excitation Raman difference spectroscopy (SERDS) for the effective separation of Raman signals from interfering backgrounds. Using a customized Raman setup based on a dual-wavelength diode laser emitting at 785.2 and 784.6 nm, we present investigations for textile analysis and identification on a set of 22 dyed and undyed pure textiles and binary textile mixtures made of cotton, viscose, wool, polyester, and elastane. SERDS in combination with multivariate analysis is demonstrated as a powerful tool for a distinction between different fiber types and fibers of one material colored with various dyes. These results highlight the large potential of SERDS for textile material identification in selected application areas.