赤外全反射吸収スペクトル測定における試料の厚さに関する考察

佐藤 公隆, 山口 直治, 神森 大彦

doi:10.2116/bunsekikagaku.17.301

赤外全反射吸収スペクトル測定における試料の厚さに関する考察

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佐藤公隆

八幡製鉄株式会社東京研究所
山口直治

八幡製鉄株式会社東京研究所
神森大彦

八幡製鉄株式会社東京研究所

書誌事項

タイトル別名

Thickness of sample in the attenuated total reflectance measurement
セキガイゼンハンシャキュウシュウスペクトルソクテイニオケルシリョウノアツサニカンスルコウサツ
赤外吸収スペクトルの鉄鋼研究への応用 (第3報)

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説明

When the analysis of surface-treated steel was done by means of infrared absorption, it was quite often that the spectra could not be obtained even in the attenuated total reflectance (ATR) method. It was found that this fail of measurement depended on the thickness of the surface layer, and the lower limit of its thickness was examined on practical specimens. The following equation showing the relationship between the thickness d and wavelength λ was derived from interference spectra:<BR>d=λ₁λ₂/4 (λ₁-λ₂) ·1/√n₂²-n₁²sin²θ₁<BR>in which n₁ and n₂ are refractive indice for different media, and θ₁ is incident angle.<BR>The result indicated that the thickness less than 20μ was inapplicable for a measurement in ATR method. The thickness of surface layer available for measurements by ATR method was estimated to be greater than 2025μ, taking simultaneously into consideration the depth of a layer into which light oozes out from boundary face.