Low temperature electron microscopy

In the case of anthracene, the stable monoclinic phase transforms under stress to a triclinic phase in which molecules are favourably oriented for dimerization to occur. Although the triclinic phase has not been isolated as a pure phase, its structure has been established using low-temperature electron microscopy and atom-atom potential calculations (Jones Thomas, 1979). In l,8-dichloro-9-methyl anthracene, isolated dislocations with (201) [010] translation bring the molecules to the required geometry (Fig. 8.17) to facilitate photodimerization. 1, 5-dichloroanthracene is an interesting case. Instead of the expected 100% head-to-head dimers, photoreaction yields 80%... 

Extensive TEM studies by Page et al. [65] delivered all previous low-temperature electron microscopy results to the consistent view that (i) silicon becomes amorphous in response to the high contact stresses under a hardness indenter and (ii) limited dislocation arrays are generated around the deformed volume at contact loads exceeding some threshold value. The authors also argued that the dislocation arrays might occur as a means of accommodating the displacements from the densification transformation, rather than as a primary response to the indenter intrusion. 

Key words Small-angle X-ray scattering - polypyrrole -polymerization - low-temperature electron microscopy... 

The membranes were either hydrated with deuterated water, or, in the case of DPPC, deuterium-substituted lipids were used in two variants with complete deuterium substitution (DPPC-d62), or with partial substitution in the choline head group (DPPC- dis) hydration in that case was performed with regular water. Also, spin-lahelled phospholipids and stearic acids were used as reference rulers. ESEEM studies were combined with PELDOR, low-temperature electron microscopy, and Monte-Carlo simulations. ... 

In this section, we analyze experiments on the relaxation of non-equilibrium Si(OOl) [12, 25] and Ge(OOl) [24] morphologies to extract values for the step-mobility as a function of temperature. Mobilities derived from the relaxation experiments are compared to more direct measurements of step-mobilities using low energy electron microscopy (LEEM) [26] and STM [27,28]. 

A variety of instmmental techniques may be used to determine mineral content. Typically the coal sample is prepared by low temperature ashing to remove the organic material. Then one or more of the techniques of x-ray diffraction, infrared spectroscopy, differential thermal analysis, electron microscopy, and petrographic analysis may be employed (7). 

Cathodoluminescence microscopy and spectroscopy techniques are powerful tools for analyzing the spatial uniformity of stresses in mismatched heterostructures, such as GaAs/Si and GaAs/InP. The stresses in such systems are due to the difference in thermal expansion coefficients between the epitaxial layer and the substrate. The presence of stress in the epitaxial layer leads to the modification of the band structure, and thus affects its electronic properties it also can cause the migration of dislocations, which may lead to the degradation of optoelectronic devices based on such mismatched heterostructures. This application employs low-temperature (preferably liquid-helium) CL microscopy and spectroscopy in conjunction with the known behavior of the optical transitions in the presence of stress to analyze the spatial uniformity of stress in GaAs epitaxial layers. This analysis can reveal,... 

Some limitations of optical microscopy were apparent in applying [247—249] the technique to supplement kinetic investigations of the low temperature decomposition of ammonium perchlorate (AP), a particularly extensively studied solid phase rate process [59]. The porous residue is opaque. Scanning electron microscopy showed that decomposition was initiated at active sites scattered across surfaces and reaction resulted in the formation of square holes on m-faces and rhombic holes on c-faces. These sites of nucleation were identified [211] as points of intersection of line dislocations with an external boundary face and the kinetic implications of the observed mode of nucleation and growth have been discussed [211]. 

Roos N. Freeze-substitution and other low temperature embedding methods, in Electron Microscopy in Biology—A Practical Approach (Harris JR, ed.), IRL Press, Oxford, UK, 1991, pp. 39-58. 

Carlemalm E, Garvito RM, Villiger W. Resin development for electron microscopy and an analysis of embedding at low temperature. JMicrosc (Oxford) 1982a 126 132-143. 

We thank A. E. Novembre and D. A. Mixon for help with GPC data, R. G. Tarascon for initial etching studies, S. A. Heffner for assistance in obtaining low temperature DSC and S. Nakahara for transmission electron microscopy. 

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