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Passport Examination by Polarized Infrared Spectra
Author(s) -
Sugawara Shigeru
Publication year - 2007
Publication title -
journal of forensic sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 96
eISSN - 1556-4029
pISSN - 0022-1198
DOI - 10.1111/j.1556-4029.2007.00487.x
Subject(s) - infrared , infrared spectroscopy , infrared spectrophotometry , poison control , medical emergency , medicine , chemistry , physics , optics , chromatography , organic chemistry
In this study, a new nondestructive technique for passport examination is proposed. In this technique, linearly polarized light is used to measure Fourier transform infrared (FT‐IR) reflectance spectra of films on the biographical data page. Thirty genuine and thirty‐five counterfeit Japanese passports and five marketed films pasted on name cards were examined. The measured spectra were analyzed as follows. The absorption spectra were obtained by the Kramers–Kronig transformations of reflectance spectra. The peak ratios were then calculated from the absorption spectra by adding the peak areas at 1126 and 1263 cm −1 and dividing the result by the peak area at 1727 cm −1 . When nonpolarized light was used, the samples could not be distinguished by comparing the peak ratios. However, when polarized light was used, they were successfully distinguished by the comparison. Therefore, polarized light is useful for the forensic discrimination of passport films by the measurement of FT‐IR spectra.