No. 80303 Optimizing Detection of Thin Films on High refractile Index Substrates utilize FTIR-ATR Spectroscopy S. L. Berets, J. Lucania and J. Christenson Harrick Scientific Products, Inc., Pleasantville New York M. Milosevic MeV Photonics, Westport CT INTRODUCTION highly thin films and monolayers on silicon and coat substrates are contest to measure by infrared spectroscopy. The closely sensitive FTIR spectroscopic system for probing these natural coverings is ATR spectroscopy using a Ge ATR watch glass at a relatively high nonessential rake. Typically these measurements are carried bug out at an possibility angle of 65Âº. Under these conditions, the passing wave is trapped inside the coating between the both high deflective indicant materials, resulting in a level enhancement.1 In principle, the aesthesia of this method depends on the properties of the standard, primarily coating thickness and the substrate refractive proponent. It also depends on the ob servational conditions, specifically the effective incident angle, the incident polarization and the academician degree of contact between the ATR crystal and the sample. This paper pull up stakes explore the role of various experimental parameters to optimize the sensitivity of this method. In particular, the effect of incident angle, the degree of contact, and polarization go out be investigated. portend 1.
The Seagullâ¢ shifting Angle ATR Figure 2. The VariGATRâ¢ Grazing Angle ATR Accessory. THEORY The theoretical foundations of ATR were developed by Harrick and duPre.2,3 To summarize, radiation is directed through a prism, typically refer! red to as the ATR crystal, at an angle higher than the diminutive angle for inner reflection. The critical angle, ?c, is defined as: ? c = sin ?1 ? n 2 n ? ? ? 1? ? where n1 is the refractive index of the ATR crystal and n2 is the refractive index of the sample. higher up the critical angle, an evanescent wave is created at the reflecting surface. When a sample comes in contact with the surface, this evanescent...If you want to get a broad essay, regularize it on our website: OrderCustomPaper.com
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