1. Use of Raman spectroscopy and chemometrics to distinguish blue ballpoint pen inks 
Flávia de Souza Lins Borba, Ricardo Saldanha Honorato, Anna de Juan 
Forensic Science International 
Volume 249, Pages (April 2015)
DOI: /j.forsciint
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2. Fig. 1
Analysis by video spectral comparator by visual inspection. Identification of numerical value alteration, (from $ to $70,000.00), using a 647nm bandpass filter.
Forensic Science International  , 73-82DOI: ( /j.forsciint )
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3. Fig. 2 Raw Raman spectra collected on ink lines.
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4. Fig. 3
(a) Three raw Raman spectra per each ink class before applying preprocessing, (b) mean spectra per each class after applying Savitzky–Golay second derivative (second order polynomial, 21 points window) and normalization.
Forensic Science International  , 73-82DOI: ( /j.forsciint )
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5. Fig. 4
Scores plot from PCA model built on the Raman preprocessed spectra of ink samples for: (a) 14 ink classes dataset (original data) (b) samples from C cluster in scores plot in (a) and (c) samples from D cluster in scores plot in (a).
Forensic Science International  , 73-82DOI: ( /j.forsciint )
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6. Fig. 5
Tree structure built based on local PCA models performed on Raman preprocessed spectra of the ink samples.
Forensic Science International  , 73-82DOI: ( /j.forsciint )
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7. Fig. 6
(a) Dendrogram obtained from Ward's cluster analysis method on Raman preprocessed spectra of ink samples and (b) enlarged view of dendrogram for distance values around 100.
Forensic Science International  , 73-82DOI: ( /j.forsciint )
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8. Fig. 7
Relevant spectral regions for discrimination among ink classes (as pointed out by VIPs values) together with mean spectra of ink classes preprocessed with Savitzky–Golay for a better comparison.
Forensic Science International  , 73-82DOI: ( /j.forsciint )
Copyright © 2015 Elsevier Ireland Ltd Terms and Conditions