XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
96
T3: O–15
Synthesis of the new type of silver SHINERS nanoresonators
with decahedral shape and their application in Raman spectroscopy
Karol Kołątaj
1
, Jan Krajczewski
1
, and Andrzej Kudelski
1
1 Department of Chemistry, University of Warsaw, Ludwika Pasteura 1, Warsaw, Poland,
e-mail: kkolataj@chem.uw.edu.pl
In this work, we report the synthesis of decahedral silver nanoparticles with silica layer
which are very new type of SHINERS nanoresonators with many sharp apexes and edges. We
also show their application for Raman studies of some molecules and yeast cells.
The synthesis of decahedral silver nanoparticles was carried out using method developed by
Kitarv et al. [1]. Synthesized nanoparticles had mainly decahedral shape with average size of 43
nm. Synthesis of thin silica layer on their surface was carried out using method developed by
Mirkin et al. [2].
Comparison studies of decahedral and spherical nanoparticles as Raman nanoresonators
were carried out by measuring Raman signal of monolayer of 4-marcaptobenzoic acid (PMBA)
deposited on Pt plate and covered with respective nanoparticles. These studies showed that
enhancement factor of used nanoparticles was approximately ten times higher in case of
decahedral nanoparticles.
Decahedral-Ag@SiO
2
nanoparticles have been tested in SHINERS measurements of
monolayers of PMBA on Pt and in measurements of model biological samples. Figure 1 shows
Raman spectra of Saccharomyces boulardii (yeast) cells before and after deposition of
decahedral-Ag@SiO
2
nanoparticles. As can be seen in this Figure, in the Raman spectrum
recorded with the decahedral-Ag@SiO
2
nanoparticles many Raman bands (e.g., at 1135, 1315,
1346, 1456, 1611, 1665 cm
–1
) can be clearly identified, whereas in a case of the Raman
spectrum recorded without nanoresonators it is very hard to distinguish these bands from the
noise.
Fig. 1. Raman spectra of Saccharomyces boulardii cells without nanoparticles (black curve)
and after addition of decahedral-Ag@SiO
2
nanoparticles (red curve).
Keywords: SERS, SHINERS, nanoparticles
References
[1] Pietrobon B., McEachran M. and V. Kitaev, ACS Nano, 3 (2009) 21.
[2] Xue, C., Chen X., Hurst S. J. and C. A. Mirkin, Adv. Mater. 19 (2007) 4071.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
97
T3: O–16
Analytical methods coupled with multivariate analysis
for differentiation of textile fibers for forensic applications
Raj Kumar
1
, and Vishal Sharma
1
1
Institute of Forensic Science and Criminology, Panjab University, Chandigarh, India,
e-mail: vsharma@pu.ac.in, sharmavishal05@gmail.com
The present work is designed to discriminate the different types of textile fiber samples by
using UV-Vis-NIR spectroscopy and stereo zoom microscopy. Microscopy provides a clear
distinction of fibers on the basis of the structural features. Several solvents for extraction of dyes
has been used that show different efficiency for different fiber samples. The conditions used for
dye extraction from the fiber are also optimized. Two approaches, i.e. visual comparison of
peaks and multivariate analysis have been proposed to differentiate the textile fibers. The UV-
Vis-NIR spectra of the dye extracted from different fiber samples give some useful clues about
the differentiation of dye present in the fiber sample. From the peaks obtained through UV-
Visible spectroscopy, the discrimination power of the samples was achieved to be 83.63 percent
for cotton fibers (black), and 94.28 percent for the wool fibers. The multivariate analysis has
further enhanced the discrimination power considerably. Welch T-test was used as a validation
tool to show the inequity between the samples that shows the close relationship in the scatter
plot.
Thus, the discrimination of fibers by multivariate analysis seems to be an effective in the
cases where fibers show similar morphology and are unable to differentiate via visual
comparison. The present work also highlights the importance of UV-Vis-NIR spectroscopy for
the analysis of textile fibers encountered in forensic cases.
Keywords: Textile Fibers, UV-Vis-NIR spectroscopy, multivariate analysis, forensic, etc.
Acknowledgment
The first author is very grateful to the UGC, New Delhi for awarding SRF fellowship. The corresponding
author is thankful to DST (Govt. of India) for providing funds through PURSE grant.
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