By combining a bolometer detector with an imaging-type interferometer, an inexpensive, easy-to-handle wide-field mid-infrared hyperspectral imaging apparatus was produced. We measured the distributions of four types of thin adhesive layers on an aluminium plate and analysed the results using correlation coefficients to visualise the distribution of various adhesives that cannot be discerned by the naked eye or conventional methods such as visible/near-infrared spectroscopic/fluorescent photography. The measurement wavelength range, obtained spectrum’s wavenumber resolution, and measurement time was 8–14 μm, about 9 cm−1, and about 30 s, respectively. Using conventional methods, adhesives could not be distinguished from the others. By using this method, we found that adhesives could be precisely distinguished by setting an appropriate threshold value for the correlation coefficient. Thus, our approach can accurately measure the spatial distribution of different types of adhesive that cannot be discriminated by conventional methods.
Adsorption of ammonia, which is the initial stage of the vapor phase epitaxial growth of nitride semiconductors, is examined by using pulsed-ammonia-beam scatterings from differently reconstructed
GaAs(111)B surfaces. It is found that the surface atomic structure of GaAs(111)B surface more strongly influences the ammonia adsorption than that of GaAs(100) surface.
Incident ammonia molecules are temporarily trapped in a deep precusor state on a (√ 19×√ 19)R23.4° surface, while they are desorbed without such a surface trapping from an As-excess (2×2) surface.
On the other hand, ammonia is efficiently stuck on a Ga-rich (1×1) surface, which is probably related to the efficient surface decomposition of ammonia under a
specific condition of nitride epitaxy. The results are discussed on the basis of the atomic arrangement of the reconstructed surface.
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.
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