Thermal Optical Microscopy Techniques

D. THERMAL OPTICAL MICROSCOPY TECHNIQUES 1. Fusion Microscopy... 

In terms of beam delivery, the DLW method is based on optical microscopy, confocal microscopy [4,6,13] and laser tweezers [14] (for reviews on laser tweezers see [ 15,16]). These techniques allow for a high spatial 3D resolution of a tightly focused laser beam with optical exposure of micrometric-sized volumes via linear and nonlinear absorption. In addition, mechanical and thermal forces can be exerted upon objects as small as 10 nm molecular dipolar alignment can be controlled by polarization of light in volumes of with submicrometric cross-sections. This circumstance widens the field of applications for laser nano- and microfabrication in liquid and solid materials [17-22]. 

Asbestos can be determined by several analytical techniques, including optical microscopy, electron microscopy, X-ray diffraction (XRD), light scattering, laser microprobe mass analysis, and thermal analysis. It can also be characterized by chemical analysis of metals by atomic absorption, X-ray fluorescence, or neutron activation techniques. Electron microscopy methods are, however, commonly applied for the analysis of asbestos in environmental matrices. 

In this era of automatic titrators, microprocessor-controlled thermal analysis, and definitive spectral techniques, one of the most powerful techniques, that is, optical microscopy, is frequently overlooked. The value of direct sample observation, preferably while it is exposed to different relative humidities, cannot be overstated. In the author s laboratory, a plexiglass chamber was constructed that can be placed on the stage of the microscope, through which air of known humidity can be circulated. This simple technique has been very useful in examining the swelling (or lack) of disintegrants and the influence of very hydrophilic excipients in combination with a moisture sensitive drug. ... 

Energy-dispersive X-ray microanalysis Surface analytical techniques Scanning near-field optical microscopy Scanning thermal microscopy Atomic force microscopy X-ray photoelectron spectroscopy... 

Michele Marrocco, PhD, is a researcher in laser spectroscopy at ENEA (Rome, Italy) (1999 to present). He received his degree in physics from the University of Rome in 1994. He was employed as a postdoctorate at the Max-Planck Institute for Quantum Optics (Munich, Germany), as a researcher at the Quantum Optics Labs at the University of Rome (Rome, Italy), and as an optics researcher by the army. His research activities include traditional and innovative spectroscopic techniques for diagnosis of combustion and nanoscopic systems studied by means of optical microscopy. The techniques used include adsorption, laser induced fluorescence, spontaneous Raman, stimulated Raman gain, stimulated Raman loss, coherent anti-Stokes Raman, degenerate four wave mixing, polarization spectroscopy, laser induced breakdown, laser induced incandescence, laser induced thermal gratings. He has over 30 technical publications. 

Hot-stage microscopy not only benefits from the features of the hot stage but also the quality and accessories of the microscope. It is obvious that this technique also needs some fundamental knowledge of chemical and optical microscopy. In this context, it should be noted that the advantage of hot stages that combine the features of differential thermal analysis (DTA) and optical microscopy are questionable since both the sensitivity of the DTA signal and the microscopic preparation features suffer much from this combination. 

The polymers, whose characteristics are summarized in Table 1, were melt mixed in a Brabender-like apparatus at 200 C and at two residence times 6 min, at 2 r.p.m. and further 10 min. at 32 r.p.m. The blend compositions are listed in Table 2. After premixing, cylindrical specimens were obtained directly by extrusion using a melting-elastic miniextruder (CSI max mixing extruder mod. CS-194), Thermal and tensile mechanical tests were performed on these specimens by an Instron Machine (mod. 1122) at room temperature and at cross-head speed of 10 mm/min. Also made were morphological studies by optical microscopy of sections microtomed from tensile samples and scanning electron microscopy of fractured surfaces of samples broken at liquid nitrogen temperature. Further details on the experimental procedures and on the techniques used are reported elsewhere . 

Differential scanning calorimetry (DSC) is a valuable aid by which phase transition temperatures, transition heats, and transition entropies can be conveniently measured or calculated. This technique offers a direct and complimentary (to microscopy) evaluation of thermal behavior. Figure 4 shows the DSC curve for 4-octyloxybenzyli-dene-4 -chloroaniline in which can be seen Kj -K2, K2 Sg, Sg-S, and S -I transitions. All transitions are enantiotropic and all are reversible. The most extensive supercooling occurs for the meso-phase-solid transition, in this case the Sg-K2 transition. Optical microscopy and/or x-ray diffraction is required to assign the specific mesophase type. 

Graphene field-effect transistors with a parylene back gate and an exposed graphene top surface have been reported [40]. A back gate stack of 168 nm parylene on 94 nm thermal silicon oxide permitted an optical reflection microscopy technique to be used for the identification of exfoliated graphene flakes. At room... 

The 10 A—1 jum size region is a difficult one in which to detect inhomogeneities. Direct techniques include the observation of the inhomogeneities by electron microscopy, and the observation of radiation (optical. X-ray or electron) scattered by the inhomogeneities In a less direct approach, the presence of inhomogeneities is inferred from their anticipated effect on measured properties thermal, optical, and electrical (discussed in Chapter 5) for example. These techniques are now briefly reviewed. 

Polymer-silica nanocomposites thus prepared are characterized by electron microscopy, scattering techniques, nuclear magnetic resonance spectroscopy, etc. to determine the structiual features. In additimi, properties such as mechanical, thermal, optical, and other important physical properties are generally determined. 

This book describes the applications of important new NMR spectroscopic methods to a variety of useful materials and compares them with results from other techniques such as adsorption, differential scanning calorimetry, thermally stimulated depolarization cmrent, dielectric relaxation spectroscopy, infrared spectroscopy, optical microscopy, and small-angle and wide-angle x-ray scattering. The text explores the application of NMR spectroscopy to examine interfacial phenomena in objects of increasing complexity, beginning with immodified and modified silica materials. It then describes properties of various mixed oxides with comparisons to individual oxides and also describes carbon materials such as graphite and carbon nanotubes. 

Although the above approaches may all be amenable to detection of crystallization in finished products, they can also be used to characterize the HME (i.e., prior to downstream processing). Further, many other techniques are often applied exclusively to the HME intermediate. For instance, optical microscopy offers excellent detectability of crystalline material in transparent extrudates. Dielectric analysis (DBA Alie et al. 2004 Bhugra et al. 2007, 2008) and thermally stimulated current IR spectroscopy (Shah et al. 2006 Rumondor and Taylor 2010), atomic force microscopy (ATM Lauer et al. 2013 Marsac et al. 2012 Price and Young 2004), and calorimetric methods have also been used to detect crystallization from an amorphous matrix (Baird and Taylor 2012 Pikal and Dellerman 1989 Avella et al. 1991). 

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