Comparison of critical adsorption scaling functions obtained from neutron reflectometry and ellipsometry

Abstract

Carpenter et al. [Phys. Rev. E 59, 5655 (1999); 61, 532 (2000)] managed to explain ellipsometric critical adsorption data collected from the liquid-vapor interface of four different critical binary liquid mixtures near their demixing critical temperature using a single model. This was the first time a single universal function had been found which could quantitatively describe the surface critical behavior of many different mixtures. There have also been various attempts to investigate this surface critical behavior using neutron and x-ray reflectometries. Results have been mixed and have often been at variance with Carpenter et al. In this paper, the authors show that neutron reflectometry data collected from a crystalline quartz-critical mixture interface, specifically deuterated water plus 3-methylpyridine, can be quantitatively explained using the model of Carpenter et al. derived from ellipsometric data.

Critical behavior in the presence of an order-parameter pinning field

“…Thus, for small values of h 0 L y ′ one observes an effective magnetization exponent which is in fact the η exponent. For the Gross-Neveu Heisenberg UC, one has η = 0.70 (15) and β/ν = 0.85(8) [75]. Since these two values are close to each other, the analysis of Ref.…”

“…[8] provides a review of experimental results, more recent studies are found in Refs. [9][10][11][12][13][14][15]. While most theoretical investigations concern with adsorption on a plane [16][17][18][19][20][21][22], the case of a nonplanar geometry was studied in Refs.…”

“…Eq. (15). Based on the value of the critical exponent η = 0.0375(5) of the three-dimensional Heisenberg UC [64], we obtain y ′ = 0.4813(3) and β/ν = 0.5188(3).…”

“…[8] for a review, and Refs. [9][10][11][12][13][14][15] for more recent results), as well as theoretical investigations (see, e.g., Refs. [16][17][18][19][20][21][22][23][24][25][26]).…”

Direct observation of critical adsorption on colloidal particles

“…To this end, neutron reflectometry has been previously employed to measure critical adsorption concentration profiles at planar surfaces. 8 While this technique is capable of probing solvent-structure over adsorption-relevant length-scales, it cannot be easily extended to colloidal particles with curved surfaces. It is important to note that the study of adsorption on curved surfaces introduces additional degrees of complexity, since adsorption phenomena are expected to be curvature dependent.…”