Kinetic description of site ensembles on catalytic surfaces

We demonstrate that the Langmuir–Hinshelwood formalism is an incomplete kinetic description and, in particular, that the Hinshelwood assumption (i.e., that adsorbates are randomly distributed on the surface) is inappropriate even in catalytic reactions as simple as A + A → A2. The Hinshelwood assumption results in miscounting of site pairs (e.g., A*–A*) and, consequently, in erroneous rates, reaction orders, and identification of rate-determining steps. The clustering and isolation of surface species unnoticed by the Langmuir–Hinshelwood model is rigorously accounted for by derivation of higher-order rate terms containing statistical factors specific to each site ensemble. Ensemble-specific statistical rate terms arise irrespective of and couple with lateral adsorbate interactions, are distinct for each elementary step including surface diffusion events (e.g., A* + * → * + A*), and provide physical insight obscured by the nonanalytical nature of the kinetic Monte Carlo (kMC) method—with which the higher-order formalism quantitatively agrees. The limitations of the Langmuir–Hinshelwood model are attributed to the incorrect assertion that the rate of an elementary step is the same with respect to each site ensemble. In actuality, each elementary step—including adsorbate diffusion—traverses through each ensemble with unique rate, reversibility, and kinetic-relevance to the overall reaction rate. Explicit kinetic description of ensemble-specific paths is key to the improvements of the higher-order formalism; enables quantification of ensemble-specific rate, reversibility, and degree of rate control of surface diffusion; and reveals that a single elementary step can, counter intuitively, be both equilibrated and rate determining.

Canadian Authors and Their Literary Agents (pp 93-120)

This essay provides an account of Canadian authors and their literary agents, from 1890-1990, in the context of recent ideas about book history and the material production of texts. My aim is to provide a new way of understanding how Canadian literature was produced and disseminated during a century marked by enormous shifts in the status and conception of the author. The paper weaves together biography, history, economics, copyright law, government policies on culture, and literary analysis in order to illustrate the role that literary agents played in the formation of Canadian authors' careers. It seeks to correct the frequently made, but incorrect assertion that professional literary agencies were not operating in Canada until the 1950s. In providing a chronological overview of the connection between Canadian authors and their associations with professional and informal agents in Canada, the US, and Britain, the essay provides the beginnings of a more detailed history of the nature of literary collaboration that existed over a turbulent century.

Erratum

In my comments in BBS (Random generators, ganzfields, analysis, and theory, 1987, 10:581-82) regarding psi, I mistakenly ascribed to Professor Honorton the position that "good experimenters knew in advance that the assertion in the paper I cited (1985), and in fact regards it as a rather foolish one (personal communication 6/25/88). This incorrect assertion was based on my inference - not his - that the most plausible alternative to optional stopping for the negative correlation between sample size and effect size (and even z-scores) was prior knowledge leading to the necessity of sampling fewer observations when the expectation of the estimated effect size was larger.Honorton, C. (1985) The Ganzfeld psi experiment: A critical appraisal. Journal of Parapsychology 49:51-91.

Infinite Doubly Stochastic Matrices

This note proves two propositions on infinite doubly stochastic matrices, both of which already appear in the literature: one with an unnecessarily sophisticated proof (Kendall [2]) and the other with the incorrect assertion that the proof is trivial (Isbell [l]). Both are purely algebraic; so we are, if you like, in the linear space of all real doubly infinite matrices A = (aij).Proposition 1. Every extreme point of the convex set of ail doubly stochastic matrices is a permutation matrix.Kendall's proof of this depends on an ingenious choice of a topology and the Krein-Milman theorem for general locally convex spaces [2]. The following proof depends on practically nothing: for example, not on the axiom of choice.