Forward recoil spectroscopy

The interface properties can usually be independently measured by a number of spectroscopic and surface analysis techniques such as secondary ion mass spectroscopy (SIMS), X-ray photoelectron spectroscopy (XPS), specular neutron reflection (SNR), forward recoil spectroscopy (FRES), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), infrared (IR) and several other methods. Theoretical and computer simulation methods can also be used to evaluate H t). Thus, we assume for each interface that we have the ability to measure H t) at different times and that the function is well defined in terms of microscopic properties. 

Measurement of transient concentration profiles of deuterated polymers in polymer blends using forward recoil spectroscopy Measurement of transient concentration profiles of fluorescently labeled molecules in capillary tubes using epifluorescence microscopy Measurement of transient concentration profiles of fluorescently labeled molecules in biological tissues using epifluorescence microscopy Fluorescence recovery (or redistribution) after photobleaching (FPR)... 

Tao, et al. [93] measured Dg (using PFGNMR and forward recoil spectroscopy) and t) of hydrogenated polybutadienes in alkanes. Polymer volume fractions extended from 0.2 up to the melt while M extended from 4.8 to 440kDa with < 1.03. Tao,... 

Tead and Kramer [122] studied diffusion of 255 kDa deuterated polystyrene through solutions of large-molecular-weight (93, 255, and 20 000 kDa) polystyrenes, with a low-M (10 kDa) polystyrene melt ts the solvent. The matrix polymer volume fraction covered 0 < < 1. Dp was obtained using forward recoil spectroscopy to measure the time-... 

Demixing, Fig. 6 (a) Volume fraction of deuterated poly (ethylene propylene), dPEP full dots), and protonated PEP (open circles) versus depth, for a degree of polymerization N 2,300 for both constituents, after a 4 h quench to r = 294 K (Tc = 365 K). Profiles are obtained with time-of-flight forward recoil spectroscopy. The dashed line indicates the surface domain thickness (f). (b) Plot showing the growth of the surface domain thickness (t) oc (From Krausch et al. [20])... 

Forward recoil spectroscopy has been employed to determine interdiffusion widths for the autohesion of a polyimide film (41). In addition, fracture energies G were measured by T-peel testing. When a was less than 20 nm, G was so low (<10 J/m ) that it was difficult to measure. At larger extents of interdiffusion, G increased linearly with a. Again, an imexpectedly large interdiffusion distance of at least 200 nm was required before complete healing was attained. 

The characterization of surface structure for miscible blends is a more formidable task, requiring techniques that are sensitive to the composition of the blend within several nanometers of the surface. X-ray photoelectron spectroscopy (xps) provided the first direct and quantitative evaluation of surface composition and surface composition gradients for miscible polymer blends of poly(vinyl methyl ether) (PVME) and polystyrene (PS) (22,23). Since that time, the situation has changed dramatically with the advance of theory and the application of exciting new experimental techniques to this problem. In addition to xps and pendant drop tensiometry (22,23), forward recoil spectroscopy (28), neutron (29) and x-ray reflectivity (30), secondary ion mass spectroscopy (either dynamic or time-of-flight-static) (31,32), and attenuated total reflectance Fourier transform infrared spectroscopy (33-35), have been applied successfully to study surface segregation. The advent of these new tools has enabled a multitechnique experimental approach toward careful examination of the validity of current surface segregation theories (36-39). 

Tao, et al. used forward recoil spectroscopy and PFGNMR to determine Ds of hydrogenated polybutadienes in alkane solvents(15). Measurements of the dynamic shear moduli were used to determine the low-shear viscosity of the same solutions. Tao, et al. s measurements of Ds appear in Figure 8.7, together with fits of Ds to scaUng-law and stretched-exponential dependences on polymer concentration and molecular weight. The root-mean-square fractional errors in the displayed fits to the scaling-law and stretched-exponential forms are both 20%. For the... 

High-resolution electron-energy loss spectroscopy Static secondary-ion mass spectroscopy Dynamic secondary-ion mass spectroscopy Forward recoil spectroscopy... 

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