Refractive index, high intrinsic

The molecular structure of the film adsorbed on a substrate such as germanium, silicon, or various common IR-transmitting salts [either before or after their surfaces were modified by standard techniques such as monolayer formation (I, 2)], is readily deduced by the internal reflection technique which has been described (3). When the substrate is a material of high reflectivity and high intrinsic refractive index such as germanium (which is used in most of our experiments), film thickness and refractive index may be determined nondestructively by ellipsometric techniques (4). A third nondestructive and noncontacting technique, which is easily applied to thin film samples on germanium or any con-... 

The detection limit is generally limited by electronic and mechanical noise, thermal drift, light source instabilities and chemical noise. But the intrinsic reference channel of the interferometric devices offers the possibility of reducing common mode effects like temperature drifts and non-specific adsorptions. Detection limit of 10 in refractive index (or better) can be achieved with these devices which opens the possibility of development of highly sensitive devices, for example, for in-situ chemical and biologically harmful agent detection. 

The application of refractive index and differential viscometer detection in SEC has been discussed by a number of authors [66-68]. Lew et al. presented the quantitative analysis of polyolefins by high-temperature SEC and dual refractive index-viscosity detection [69]. They applied a systematic approach for multidetector operation, assessed the effect of branching on the SEC calibration curve, and used a signal averaging procedure to better define intrinsic viscosity as a function of retention volume. The combination of SEC with refractive index, UV, and viscosity detectors was used to determine molar mass and functionality of polytetrahydrofuran simultaneously [70]. Long chain branching in EPDM copolymers by SEC-viscometry was analyzed by Chiantore et al. [71]. 

Our ThFFF channel is similar to the model TlOO Thermal Fractionator (FFFractionation, Inc., Salt Lake City, UT), with a channel thickness of 0.10 mm. When the carrier liquid was tetrahydrofuran (THF) or cyclohexane, a UV monitor set at 254 nm was used for sample detection when toluene was the carrier liquid, a refractive index monitor was used instead. The temperature difference was 60.0 K and the cold wall temperature was 298.2 K. Intrinsic viscosities were measured with a CannonFenske ASTM-25 viscometer obtained from Fisher Scientific (Santa Clara, CA). Viscosities were measured in a thermostated temperature bath set at T g. All solvents were high-performance liquid chromatography grade. 

Beyond the intrinsic, multi-phonon absorption bands (between 4000cm and 1500cm ) [30], the transmission of the CVD diamond specimen reaches the maximum reflectivity limited value (Fig. 5) of 71.4% (using a refractive index value of 2.375 [32,3]) and is identical, within experimental accuracy, to that of high-quality single crystal Type Ila samples measured with the same instrument. 

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