Reflection anisotropy microscopy

Optical methods are eminently suitable for imaging, the attractive property of photons being that they do not require vacuum. Hence, imaging under reaction conditions becomes possible. Among the successfully applied methods are infrared imaging (IRI) and reflection anisotropy microscopy (RAM) [72]. We will discuss ellipsomicroscopy for surface imaging (EMSI) in some detail here [74],... 

Since the PEEM technique is based on the emission of electrons, its application is restricted to pressures below about 10 mbar. Eor higher pressures, two optical methods were adopted ellipsometry for surface imaging (EMSI) and reflection anisotropy microscopy (RAM) [15]. 

Optical microscopy is another method that has been used to determine the distribution of minerals in coal. This method is based on the detailed microscopic examination of polished or thin sections of coal in transmitted and/or reflected light. In principle, observing several of its optical properties, such as morphology, reflectance, refractive index, and anisotropy, makes identification of a mineral type possible. 

Deformation by intracrystalline slip and dynamic reaystallization. These are important mechanisms for the development of crystallographic preferred orientation (CPO) and property anisotropy. Slip bands associated with intracrystalline flow may easily be seen in optical reflection microscopy of previously flattened and polished surfaces of specimens that are subsequently deformed as described above. CPO developments are less easily demonstrated, because it required the making of thin sections of deformed ice and the use of a simple universal stage to determine the orientation of the crystallographic c axis. 

Polarised l t microscopy, in which the sample is illuminated with Hnearly or circularly polarised light, either in a reflection or transmission mode. One polarising element, located below the stage of the microscope, converts the illumination to polarised light, while a second polariser is located between the objective and the ocular and is used to detect polarised light. Various characteristics of the specimen can be determined, including anisotropy, polarisation colours, birefringence, and polymorphism. 

The optical anisotropy of cokes gives rise to a characteristic pattern of extinction contours when a polished surface is examined by polarized light microscopy using crossed polars, or reflection interference colours if the polars are parallel and a half wave plate is inserted into the optical system (, 12) ... 

Brooks and Taylor (1968) reported changes in the microscopy of vitiinite (reflectance and bireflectance) with distance from the dyke. The vitrinite, at a distance of 1 km from the dyke, was unaltered and retained its anisotropy resulting from the overburden pressures. 

However, for a certain polymer, the signs and patterns of the CD spectra were unchanged, hi addition, changing the direction and orientation of the film sample did not significantly affect the spectral intensity and pattern. Furthermore, the films did not show birefringence in polarized optical microscopy analysis. These observations rule out the possibility that the CD spectra are due to linear dichroism based on film anisotropy and support that the film spectra reflect molecular chirality. CD absorptions similar to those indicated in film were observed also for a decalin suspension of THF-insoluble polymer (fine power ground with a mortar) synthesized using (-)-Sp-FILi. This further supports that the CD spectra in film (Fig. 34) do not arise from sample anisotropy. 

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