Application of Raman spectroscopy to forensic fibre cases

Resonance Raman and UV–visible spectroscopy of black dyes on textiles

“…Viscose shows a similar Raman spectrum to that of cotton, consistent with its cellulose composition. The polycotton sample shows some relatively weak cellulose bands and its Raman spectrum is dominated by much stronger bands from polyester, as confirmed by the Raman spectrum of polyester alone; the spectra from cotton and polyester reported here are comparable to those given in the literature [20]. The acrylic sample showed very strong emission that obscured any Raman bands.…”

“…The rich Raman spectrum of this dye gives multiple bands of various relative intensities that together provide an excellent identification signature. The Raman spectra reported here are also comparable to those reported in the literature for Reactive Black 5 in forensic casework fibres analysed under a microscope with the same 514.5 nm excitation wavelength as that used here [20].…”

“…The use of Raman spectroscopy in forensic science has also received increasing attention, and examples include reports of its application to analyse body fluids [3], drugs and explosives [4][5][6][7], paints [8][9][10], pen inks [11][12][13][14][15], and lipsticks [16]. Studies exploring the use of resonance, non-resonance, and surface-enhanced Raman spectroscopy for forensic fibre examination have also been reported, including those of both dyed and non-dyed textile fibres [17][18][19][20][21][22][23][24][25].…”

“…The alternative vibrational technique of infrared spectroscopy is less sensitive than resonance Raman spectroscopy and it is generally not suitable for the analysis of dyes in fibres because the dyes are typically present at relatively low concentration; however, infrared spectroscopy can be used for analysing the fibre substrates themselves, in the presence or absence of dyes [30]. In general, Raman spectroscopy can use a wide range of laser wavelengths, sampling conditions, instrumentation, and data-processing methods, such that its practical application can require careful consideration, as reported and discussed in the context of forensic fibre analysis [17][18][19][20][21][22][23][24][25]. The optimum conditions for recording resonance Raman spectra can vary significantly between samples, but it may be impracticable to optimise the conditions for each sample in routine analytical work, where a fixed set of conditions that generate good data from many samples may be advantageous.…”

Forensic Analysis of Fibres by Vibrational Spectroscopy

“…The usefulness of Raman spectroscopy in actual forensic fibres cases has been discussed in a recent report [39]. Five different cases were discussed.…”