Internal-reflection type

Tokunaga M, Kitamura K, Saito K, Iwane A H and Yanagida T 1997 Single molecule imaging of fluorophores and enzymatic reactions achieved by objective-type total internal reflection fluorescence microscopy Biochem. Biophys. Res. Commun. 235 47-53... 

Langmuir-Blodged films have been deposited on many different substrates. The substrates used include different types of glass (such as quartz for UV-visible spectroscopy) CaF2 plates for transmission infrared spectroscopy silicon, germanium, and ZnSe plates for internal reflection infrared spectroscopy. For electrochemical applications, LB films... 

Figure 7. Exemplary Raman sensor layouts a reflection-type probe with single excitation fibre and collection fibre bundle b angular probe with internal laser diode c sensing fibre probe.

This type of mode can exist only under certain conditions related to the geometry of the microtube and the refractive indices of the three regions. By defining the incident and reflection angles at r = R and r R2 as 6t and 02, the light transmitted through the inner boundary and totally internal reflected at the outer boundary should satisfy the following three criteria ... 

Final justification for using terms such as inner- or outer-sphere awaits direct spectroscopic confirmation. Electron Spin Resonance, Mossbauer, and Fourier Transform Infrared-Cylindrical Internal Reflection Spectroscopic techniques are being used to establish the structure of surface complexes (see, e.g., McBride, Ambe et al., and Zeltner et al., this volume). The potential for using EXAFS (extended x-ray absorption fine structure) to establish the type of surface complex for Pb + adsorbing onto goethite is currently being undertaken in our laboratory. 

Short path length flow cells may be used in lower volume, or lower flow situations. The extremely small gap between the optics of fibers limits them to these types of applications. It is possible to make flow cells with sample gaps as small as 25 um, so that they may be used with highly absorbing species. With even higher absorbing species, attenuated total internal reflection (ATR) probes may be appropriate (see below). 

The ATR technique is now routinely used for IR spectroscopy as it allows measurement of spectra for a variety of sample types with minimal preparation. The crystals employed are generally prismatic in shape, allowing contact of a flat surface with the sample. The ATR method was first adapted for HP IR spectroscopy by Moser [29-33], who realised that a conventional autoclave could easily be adapted for in situ IR spectroscopy by fitting an ATR crystal of cylindrical cross section. The technique developed by Moser is thus known as cylindrical internal reflectance (CIR) spectroscopy and high pressure cells based upon the CIR method have been commercialised by Spectra-Tech. A typical CIR cell is illustrated in Figure 3.8. 

Internal reflection spectroscopy is widely applied for on-line process control. In this type of application, the chemical reactor is equipped with an internal reflection probe or an IRE. The goal of this type of application is the quantification of reactant and/or product concentrations to provide real-time information about the conversion within the reactor. In comparison with other analytical methods such as gas chromatography, high-pressure liquid chromatography, mass spectrometry, and NMR spectroscopy, ATR spectroscopy is considerably faster and does not require withdrawal of sample, which can be detrimental for monitoring of labile compounds and for some other applications. 

Attenuated total internal reflection (ATR) probes offer several advantages over other probe types. ATR is a phenomenon that relies on a difference in the index of refraction of a crystal and that of the solution with which it is in contact to prevent light from escaping the crystal. Only the evanescent wave of the light interacts with the solution layer at the crystal face. The result is an optical pathlength of only a few microns. Typical designs make use of faceted crystals or hemispheres (see Figure 6.1). The most common ATR material in the UV-vis is sapphire. In rare cases, fused silica may be used. ATR allows spectra to be taken of neat samples with optical density (OD) of 500-1000... 

Figure 2.6 Application of splinted RNA ligation procedure single molecule FRET. (A) Diagram of prism-type total internal reflection fluorescence microscope (TIRFM) for single molecule FRET measurements. (B) Distribution of single-molecule FRET values for dye-labeled telomerase RNA molecules generated by splinted RNA ligation. (C) Dye intensity and FRET traces of a single telomerase RNA molecule Cy3 emission (green), Cy5 emission (red), FRET ratio (blue).

Total internal reflection fluorescence, 268 Transient receptor potential vanilloid type-1, 44, 240... 

A Mutiple Internal Reflection Accessory for use with Perkin-Elmer infrared spectrophotometers was used to introduce the sample to the IR beam. To correct for losses in energy transmittance through the sample beam resulting from the use of the MIR Accessory, a comb-type reference beam attenuator was employed. A LFE Corpora-... 

The experimental aspects of the performance of in situ FTIR measurements are described in Refs. 43 and 44. Figure 13 shows a typical cell for in situ external reflectance mode (e.g., SNIFTIRS type measurements) [94,95], The experimental aspects of its use are described in Ref. 96. Figures 14 and 15 show cells for in situ internal reflectance modes multiple internal reflectance ATR and single internal... 

Because of the dependence of the PL intensity of TiC>2 on the nature of the gas-phase molecules introduced (alcohols) and its reversibility upon elimination of the molecules by flowing dinitrogen, there is hope that such an effect can be applied to gas sensors. With the combined use of several techniques (PL, time-resolved femtosecond diffuse reflectance spectroscopy, multiple internal reflection IR absorption), the dynamics and role of photogenerated electrons and holes in the absence or presence of metals (notably platinum) are now better understood, at both the gas-solid and liquid-solid interfaces. It is also likely that not only TiOz, but other types of semiconductors will be more thoroughly investigated in the future. 

Fig. 15.1. Schematic representation of amyloid fibrils revealed by total internal reflection fluorescence microscopy, (a) The penetration depth of the evanescent field formed by the total internal reflection of laser light is 150nm for a laser light at 455 nm, so only amyloid fibrils lying parallel to the slide glass surface were observed. (b) Schematic diagram of a prism-type TIRFM system on an inverted microscope. ISIT image-intensifier-coupled silicone intensified target camera, CCD charge-coupled device camera...

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