Development and evaluation of a simple Raman spectral searching algorithm

Raman spectroscopy has grown to a frequently applied technique in the analysis of art and archaeological objects. The growth in applications is further driven by the development of new, small and compact spectrometers that are well suited for in situ analysis. Different spectral databases have been composed, to allow fast identification of the materials at hand. However, the automated identification of the highly similar spectra of contemporary synthetic organic pigments is not straightforward, as spectral libraries that contain several hundreds of spectra are typically recorded on benchtop spectrometers that have different spectral resolutions and sensitivities and often use different excitation laser wavelengths. Therefore, here a simple automated spectral searching algorithm is proposed that is based on the comparison of a series of Raman band positions, to identify the materials. Thus, many of these interferences can be avoided. In this work, the proposed algorithm is tested on spectra that were recorded by using portable Raman instruments on mock-up samples as well as during the in situ analysis of street art. Graphic abstract: [Figure not available: see fulltext.]