A novel time‐of‐flight detector system for He+ forward recoil spectrometry which improves the depth resolution to better than 35 nm has been used to investigate the form of the surface enrichment profile in a protonated (normal) polystyrene (PS)/deuterated polystyrene (d‐PS) blend. The volume fraction ϕ of d‐PS depends on the depth z as ϕ(z)=ϕ ∞ +(ϕ 1 -ϕ ∞ ) exp(-z/ξ), where ϕ 1 and ϕ ∞ are the surface and bulk volume fractions of d‐PS, respectively, and ξ is approximately the bulk correlation length, as predicted by theory.
[Show abstract][Hide abstract] ABSTRACT: The interfacial composition profile bwtween two polymer phases at temperatures below the upper critical solution point has been measured directly, using an ion-beam method based on nuclear reaction analysis. The interface width grows with time to a finite limiting value. The variation of the limiting interfacial width as the critical temperature is approached from below is in quantitative accord with mean-field theories.
[Show abstract][Hide abstract] ABSTRACT: We describe a method based on nuclear reaction analysis, using the reaction <sup>2</sup>H(<sup>3</sup>He, <sup>4</sup>He)<sup>1</sup>H, (Q=18.352 MeV) to determine composition profiles of deuterated polymer chains in thin films. By detecting the emitted α particles (<sup>4</sup>He) at forward angles (30°) we are able to achieve a spatial resolution of 7 nm half width at half maximum (HWHM) at the deuterated sample surface, and 15 nm HWHM at a depth of some 130 nm. We use our method to probe initial diffusional broadening at the interface between deuterated and protonated polystyrene films. Our measured profiles are in close agreement with earlier measurements (over larger spatial scales) and with mean field models for the diffusional process in this system.
[Show abstract][Hide abstract] ABSTRACT: A novel method of precise identification of the depth location of light atoms based on ERD analysis is described. The method utilizes two detectors situated at different angular locations. From the energies at which the common distinctive features of the spectra are observed, the recoil angle can be determined with a mean error of less than +/- 0.1°. The relevant uncertainty in the depth identification is less than +/- 1 nm, which is more than 10 times smaller than the projected range of 1 keV protons in carbon. An example of the application of this method to the analysis of a carbon limiter in a tokamak is also described to show the effectiveness of the method.
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 10/1990; 51(4):446-451. DOI:10.1016/0168-583X(90)90566-D · 1.12 Impact Factor
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