Surface-Enhanced Resonance Raman Scattering and Near-Infrared Fourier Transform Raman Scattering as in Situ Probes of Ink Jet Dyes Printed on Paper

Abstract

The characterization of ink jet dyes and inks printed onto paper surfaces is of importance for the development of ink jet ink formulations and for use in forensic science. Raman spectroscopy is an effective and informative probe for this purpose if problems associated with fluorescence are overcome. A comparison is made here between two effective techniques, surface-enhanced resonance Raman scattering (SERRS) and near-infrared Fourier transform Raman scattering (NIR-FTR). SERRS provides a good method for obtaining in situ measurements using a visible laser system. It is fast (1–10 s accumulations) and requires very low laser powers (<1 mW). However, it requires the addition of a small dot of silver colloid to the paper surface in order to produce the enhancement. NIR-FTR is noninvasive and simpler to use. However, much higher laser powers are required (>200 mW), and the spectral accumulation time is significantly longer. Both methods overcome fluorescence effectively in most samples studied; however, each is more effective than the other with selected inks and paper substrates. SERRS involves resonant enhancement of the chromophore of the dye in contact with the silver surface, and consequently it is the dye chromophore which is uniquely identified. With NIR-FTR, signals from the paper and the filler are also observed. Comparable spectral patterns with clear, explicable differences are obtained from each method, indicating in particular that SERRS spectra can be interpreted without recourse to specific surface selection rules. The combination of the two techniques provides some information on the electronic as well as the vibrational properties of the dyes in situ.

Kerr gated resonance Raman spectroscopy in light fastness studies of ink jet prints

“…In analyses of colorants and ink jet inks, the use of near-infrared excitation (NIR-FTR) and surfaceenhanced resonance Raman scattering (SERRS) has been one strategy as a means to avoid or attenuate the sample-related fluorescence. 6,11 Nevertheless according to the results, fluorescence still proved to be a problem in NIR-FTR measurements, whereas in SERRS, the required intrusive sample pre-treatment prevented the prints from being studied naturally. The fluorescence problem has also been alleviated to some extent by using an immersion objective in the NIR-Raman measurements of the prints, or by collecting the spectra using laser wavelengths in the UV region.…”

“…[6][7][8][9] As the method is sensitive particularly to the aromatic structures and double bonds, it enables the detection of even minor amounts of the colorants on the paper surfaces and analysis of ageing, e.g. light-induced changes.…”

Forensic Discrimination Potential of Video Spectral Comparator and Micro Spectrophotometer in Analyzing Question Document and Fraud Cases in India

“…Furthermore, the development of increasingly close links between forensic laboratories has necessitated, on the one hand, establishment of common standards of research, and on the other, the widespread introduction of quality ensuring procedures in order to obtain full repeatability and reliability in conducted research. The present work concerns research into the possibility of differentiating between blue ballpoint pen inks by means of five techniques which do not require the destruction of the document, based on the following: measurement of the level of absorption and luminescence of ballpoint pen inks in visible, Infrared light and Raman absorption spectrometry [2][3][4]; and one technique which destroys the document -thin layer chromatography [5]. The discriminative powers of the particular methods were compared in the course of analyzing blue ballpoint pen inks produced by four popular firms that guarantee good quality and uniformity of their products.…”

Forensic discrimination of inkjet-printed lines by Raman spectroscopy and surface-enhanced Raman spectroscopy

“…times 19 . Surface-enhanced Raman spectroscopy (SERS) has been reported in the literature as a method for quenching fluorescence in printer ink analysis 19,20 .…”

“…Surface-enhanced Raman spectroscopy (SERS) has been reported in the literature as a method for quenching fluorescence in printer ink analysis 19,20 . In SERS, samples are treated with a nanostructured metallic colloid, usually made of silver or gold, and once it has been effectively adsorbed into the sample, the surface becomes SERS active and fluorescence can be quenched almost completely.…”