Thermal optical reflectance

A variety of methods have been applied to the measurement of EC and OC in aerosol samples with the thermal, thermal optical reflectance (TOR), and thermal manganese oxidation (TMO) methods being the most popular. Understanding the operational principles of these methods is often necessary for the interpretation of reported EC and OC data. 

FIGURE 14.A.1 Example of a thermal/optical reflectance carbon analyzer thermogram for an ambient sample collected in Yellowstone National Park (Chow et al. 1993). Reflectance and FID output are in relative units. Reflectance is normalized to initial reflectance and FID output is normalized to the area of the reference peak. (Reprinted from Atmos. Environ. 27, Chow et al., 1185-1201. Copyright 1993, with kind permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington 0X5 1GB, UK.)... 

Chow, J. C., Watson, J. G., Pritchett, L. C., Pierson, W. R., Frazier, C. A., and Purcell, R. G. (1993b) The DRI thermal/optical reflectance carbon analysis system description, evaluation and applications in U.S. air quality studies, Atmos. Environ., 27, 1185-1201. 

Since that discovery a major aspect of our research effort has been to develop a method to account for this unwanted pyrolytic conversion of organic to elemental carbon. This report describes a combined thermal-optical instrument in which the reflectance of the filter sample is continuously monitored during the thermal analysis. Dod (14) have also reported a combustion... 

The metallic nature of concentrated metal-ammonia solutions is usually called "well known." However, few detailed studies of this system have been aimed at correlating the properties of the solution with theories of the liquid metallic state. The role of the solvated electron in the metallic conduction processes is not yet established. Recent measurements of optical reflectivity and Hall coefficient provide direct determinations of electron density and mobility. Electronic properties of the solution, including electrical and thermal conductivities, Hall effect, thermoelectric power, and magnetic susceptibility, can be compared with recent models of the metallic state. 

Figures 13 and 14 show the crystal structure and the temperature dependence of electrical conductivity measured along the one-dimensional axis, fc-axis, of TTF-TCNQ [53]. The conductivity increases with decreasing temperature down to about 60 K below which the conductivity is characterized by thermally activated nature. The metallic properties are ascertained by much experimental evidence such as optical reflectivity, spin-magnetic susceptibility, and thermopower [54]. In the insulating state similar measurements also suggest the presence of a band gap at the Fermi level. These measurements suggest the metal-insulator transition to oceur at 53 K.

In order to ablate material with a laser, it is necessary to surpass a material-dependent energy volume density [19]. For fixed laser parameters, the ablation behavior of any sample is primarily influenced by its optical (reflectivity R, linear absorption coefficient a) and thermal (thermal diffusivity S) properties. Therefore, ablation thresholds Fth and rates per pulse d vary. 

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... 

Conventional polymers do not always possess the combination of desired bulk and surface properties for a specific application. The polymer materials used for microfluidic devices are innately hydrophobic, low-surface-energy materials and thus do not adhere weU to other materials brought into contact with them. This necessitates their surface modification/treatment to render them adhesive. This has prompted the development of a variety of polymer modification techniques, with the aim of developing new materials from known and commercially available polymers that have desirable bulk properties (elasticity, thermal stability, permeability, etc.) in conjunction with newly tailored surface properties (adhesion, biocompatibUity, optical reflectivity, etc.). 

Thermal microscopy, reflectance thermometry and scanning optical thermometry measurement methods in micro- and nanodevices have been reviewed by Cahill et al. [59]. 

As a first step, it is important to prove the existence of hybridization gaps in heavy-fermion systems and then show that thermal excitations across this gap at elevated temperatures influence the physical properties in the observed way. The first experimental evidence of a hybridization gap has been given by Marabelli et al. (1986a) by far infrared optical reflectivity measurements at low temperatures and in more recent years this method has been extended to many other heavy-fermion compounds so that the author now believes that the hybridization (pseudo) gap is a general feature of all heavy fermions. 

Fig. 121. Thermally modulated reflectivity AR/R for (200)-textured EuSe films on Pyrex (a) and thermally modulated transmissivity AT/T for EuSe films on quartz (b) at 4.3 K in the AF-I (H = 0) and ferrimagne-tic state (H = 3 kOe) compared with the optical density (c) of AF-1 EuSe at 4.3 K.

GOS] XRD, thermal analysis, FTIR spectroscopy, optical reflection analysis, TEM, Mossbauer spectra 80, 298 K Fc203-Al203 system up to 10% AI2O3... 

Thermal Fixation Properties of Disperse Dyes on Polyester—Gotton. This method assesses the fixation properties of disperse dyes as a function of the time, temperature, dyestuff concentration, or presence and amount of auxiUary agents. The polyester—cotton fabric is padded and dried, the cotton dissolved in sulfuric acid and washed out of the blend, and the amount of dye on the polyester component assessed by either reflectance or measuring the optical density of a solution of dye obtained by extracting the dye with boiling chloroben2ene solvent. 

---