| Abstract
| - Near-infrared (NIR) spectroscopy is ill-suited to microanalysis because of its low absorptivity. We havedeveloped a highly sensitive detection method for NIRspectroscopy based on absorption-sensitive surface plasmon resonance (SPR). The newly named SPR−NIRspectroscopy, which may open the way for NIR spectroscopy in microanalysis and surface science, is realizedby an attachment of the Kretschmann configurationequipped with a mechanism for fine angular adjustmentof incident light. The angular sweep of incident lightenables us to make a tuning of a SPR peak for an absorption band of sample medium. From the dependencesof wavelength, incident angle, and thickness of a gold filmon the intensity of the SPR peak, it has been found thatthe absorbance can be enhanced by ∼100 times compared with the absorbance obtained without the gold filmunder optimum conditions. This article reports the detailsof the experimental setup and the characteristics ofabsorption-sensitive SPR in the NIR region, together withsome experimental results obtained by using it.
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