Reflectometry

The polymer concentration profile has been measured by small-angle neutron scattering from polymers adsorbed onto colloidal particles [70,71] or porous media [72] and from flat surfaces with neutron reflectivity [73] and optical reflectometry [74]. The fraction of segments bound to the solid surface is nicely revealed in NMR studies [75], infrared spectroscopy [76], and electron spin resonance [77]. An example of the concentration profile obtained by inverting neutron scattering measurements appears in Fig. XI-7, showing a typical surface volume fraction of 0.25 and layer thickness of 10-15 nm. The profile decays rapidly and monotonically but does not exhibit power-law scaling [70]. 

Schaaf P, Dejardin Ph and Schmitt A 1985 Reflectometrie appliquee aux interfaces diffuses possibilites et limites de la technique Rev. Phys. Appl. 20 631-40... 

These samples were measured non-destructively by energy-dispersive XRF with synclirotron radiation excitation (SYXRS), by g-XRF, by wavelength-dispersive XRF (WDXRS), and by Rutherford back scattering (RBS), by X-ray reflectometry (XRR) and by destructive secondary ion mass spectrometry (SIMS) as well (both last methods were used for independant comparison). 

A commonly used form of internal modulation is differential reflectometry, in which the reflectance of the sample under investigation (or a portion of it) is compared to a standard material. This can be accomplished either by holding the sample stationary and scanning the probe beam between two regions or by holding the l t spot fixed and moving the sample. ... 

Reflectometry is a useful probe with which to investigate the structure of multilayers both in self-supporting films and adsorbed on surfaces [51]. Specular X-ray reflectivity probes the electron density contrast perpendicular to the film. The X-rays irradiate the substrate at a small angle (<5 °) to the plane of the sample, are reflected, and are detected at an equal angle. If a thin film is present on the surface... 

X-ray reflectometry/ scattering (XR) X-rays X-rays 0.2 nm yes quantitative 0.1 nm mm roughness, composition profile... 

X-ray reflectometry (XR) has already been described in Sect. 2.1 as a technique for polymer surface investigations. If a suitable contrast between components is present buried interfaces may also be investigated (Fig. 4d) [44,61,62]. The contrast is determined by the difference in electron density between materials. It is, in the case of interfaces between polymers, only achieved if one component contains heavy atoms (chlorine, bromine, metals, etc.). Alternatively the location of the interface may be determined by the deposition of heavy markers at the interface. 

Several methods based on the utilization of x-rays are nsed to study LB fihn structure. Diffractometry and reflectometry are the nsnal ones. Diffractometry is nsed mainly when well-ordered periodic strnctnre is under the investigation and several Bragg reflections are in the x-ray pattern. The position of these reflections is determined by the Bragg eqnation ... 

Melting temperature Time domain reflectometry Tumor-inducing Time-of-flight... 

More sophisticated methods that actually measure volumetric water content can also be used, such as time domain reflectometry (TDR). In Figure 14, an example of TDR results is presented. Both the calculated and measured (i.e., TDR) volumetric water contents provide a similar picture of the profile water status by depth with time. Proper soil characterization data, such as those shown in Table 6, are necessary for these calculations and improve understanding of the test system. The determination of water-holding capacity (WHC) at 0.03 MPa field capacity (FC) and 1.5 MPa... 

Performance data Two moisture monitoring systems were installed, one at Disposal Area A and one at Disposal Area AB plus in May and November 1999, respectively. Each monitoring system has two stacks of time domain reflectometry probes that measure soil moisture at 24-in. intervals to a maximum depth of 78 in., and a station for collecting weather data. Based on nearly 3 years of data, there is generally <5% change in the relative volumetric... 

Bone, R. A. et al. (2007a). Macular pigment, photopigments and melanin Distributions in young subjects determined by four-wavelength reflectometry. Vision Research 47 3259-3268. 

Delori, F. C. et al. (2001). Macular pigment density measured by autofluorescence spectrometry Comparison with reflectometry and heterochromatic flicker photometry. Journal of the Optical Society of America A 18 1212-1230. 

Eisner, A. E. et al. (2000). Scanning laser reflectometry of retinal and subretinal tissues. Optics Express 13 243-250. 

Kilbride, P. E. et al. (1989). Human macular pigment assessed by imaging fundus reflectometry. Vision Research 29 663-674. 

Van de Kraats, J. et al. (1996). The pathways of light measured in fundus reflectometry. Vision Research 36 2229-2247. 

Structure of Thin Films and Plane Surfaces is studied in a grazing-incidence recipient by means of grazing incidence (GI) methods GISAXS, GIWAXS, or by X-ray reflectometry (XR). 

In addition, typical methods of sensing are total internal reflection fluorescence or monitoring of fluorescence resonance energy transfer6,7. The second class is a direct optical detection principle which relies either on reflectometry or refractometry. The latter is connected to evanescent field... 

Figure 2 demonstrates the principles of reflectometry and reffactometry by using a waveguide with a refractive index that is higher by n2 than that of the environment (ni). Radiation incident to an interface between media with different refractive indices is reflected in part most penetrates the medium. The radiation is reflected and refracted in dependence on the angle of incidence and the ratio of refractive indices in the two media according to Snellius law... 

Hyphenated techniques like combination of optical detection methods based on reflectometry or refractometry and separation techniques are of future interest. The same is valid for the intention to couple SPR or RIfS with mass spectrometry like MALDI33. 

Field methods of measuring soil water are primarily designed to measure water in the range of -10 to -1500 kPa of pressure. However, different instruments have different ranges as shown in Table 5.1. Tensiometers, porous blocks, and thermocouple psychrometers are usually installed in the field and measurements are taken on a regular basis. Neutron probe and time domain reflectometry (TDR) equipment are usually carried to the field each time a... 

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