Geometries infrared imaging

Infrared Imaging and Mapping for Biosensors, Fig. 2 Schematic of transmission, external reflection, and internal reflection modes at multiple incidence angles (p. For the internal reflection, a single reflection in attenuated total reflection (ATR) geometry is shown exemplar-ily. The polarization of the E-field of the incident radiation parallel (p-polarized) and perpendicular to the incidence plane (s-polarized) is marked in the transmission and... 

Solid and solution phase fluorescent spectra at room temperature exhibit relatively broad, often mostly featureless excitation (absorption) and emission spectra, particularly when compared to mid- and far-infrared spectroscopies. These spectra are often mirror images of each other but there are several exceptions as a result of either disparate molecular geometries between the ground and excited states or when the fluor is an excimer. ... 

In order to enhance spatial resolution, it is necessary to make the NA of the objective larger, as is clear from Equation (17.3) that is, either n or 6, or both of them should be increased. Due to the optical geometry of a microscope, there is an upper limit for 0. On the other hand, it is possible practically to increase n by introducing an attenuated total reflection (ATR) accessory into a microscope (see Chapter 13 for the ATR method this is a frequently used accessory for many recent infrared microspectroscopy absorption measurements). The refractive index n of Ge, which is a commonly used material for an internal reflection element (IRE) in the ATR method, is about 4, and the NA when using a Ge IRE exceeds 2. This means that, if an ATR accessory with a Ge IRE is combined with a microscope, the theoretical spatial resolution is enhanced about four times that of the conventional reflection measurement. In fact, in the FT-IR microspectroscopic imaging measurement with a Ge ATR accessory, it has been confirmed that a spatial resolution comparable to the infrared wavelength used for the measurement is realized, and thus a higher spatial resolution may be attainable. 

Figure 13 (a) Schematic illustration of the interaction geometry between the infrared ultratast pulsed radiation from the FEL and the carbon-metal target. HRTEM images of as-prepared SWNT soot supported on a holy carbon grid, produced with (b) NiY catalysts and (c) NiCo catalysts. Adapted with permission from Ekiund, P. C. Pradhan, B. K. Kim, U. J. etal. Nano Lett. 2002,2.561. Copyright 2002 American Chemical Society. 

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