Asymmetric Research Articles

A Localized Molecular Orbital Study of the Structure and Bonding of Ozone.

The locali zed molecular o rbital th eory and e ne rgy partiti on in g formali sm have been in voked to study th e stru cture and bonding in ozone molecule. The range o f in vestigati o n covers a large numbe r o f confo rmations generated th eore ti cally ove r th e wide range of apical angles between angular (C21.) to linear (0 =11 ) shapes. The results demonstrate that. similar to th e bonding in diborane, th e re are two equi valent three-cente red bonds in ozone embracing three oxygen atoms in all th e conformations . The possibilit y of a triangular struc ture of ozone is ruled out because the computed locali zed mo lecular orbit als demo nstrate that the re is no bonding between the termin a l oxygen atoms and the decomposed e ne rgy compone nt s show that th e interaction between terminal oxyge n atoms is stro ng ly repul s ive. Charge de ns ity di stribution is asy mmetric in th e ho monu c lear mo lecule and it s dipo le mo ment is a n al gebraic sum of bond moment a nd lone pair mo ment a nd lo ne pair o n th e apical oxygen ato m contributes significantl y to the dipo le mo ment. It is de mo nstrated that a ny atle mpt of calculatin g th e apical an g le from the ex perimentall y determined dipole mo me nt would be erroneous and mi s leadin g. Variation of dipo le mo ment as a function of angular to linear reorganization of mo lecular shape is correlated in terms of computed quantum mechanical hybridi zation of the lone pair o n th e apical oxygen a to m. The barrier to in ve rsion of ozone th ro ugh th e lin ear (0=1, ) trans iti o n state originates from a subtl e inte rpla y of one- and two- cente r energy compone nts over the e ntire skeleton of th e molecule.

Fourier transform infrared spectroscopy of corona-processed silicon dioxide films

The application of corona discharge during the thermal oxidation of Si substrates has been shown to dramatically enhance the growth rate at low temperatures. Fourier transform infrared spectroscopy (FTIR) of the films shows that these films have properties close to those of untreated oxides. No-hydrogen related impurities are introduced into these films by the corona processing. However, subtle changes in the shape and intensity of the main Si–O–Si asymmetric (AS) stretch vibration at 1070 cm−1 indicate that the films have a different structure than that of standard thermal SiO2 films. The changes in frequency and full width half maximum (FWHM) of the AS peak are described as a function of corona-treatment parameters. The peak frequency and FWHM of positive-corona-treated films shift in a direction consistent with relaxation of thermal SiO2 films. However, for negative-corona-treated films the shifts are in the opposite (unexpected) direction. Coupled FTIR and etch-back measurements indicate that both positive- and negative-coronaprocessed films are homogeneous.

The War of Attrition in Continuous Time with Complete Information

This paper provides a complete characterization of the Nash equilibrium outcomes for the war of attrition when time is continuous and information is complete. It allows for asymmetric payoffs and an arbitrary time horizon. In addition to certain (asymme tric) pure strategy equilibria that always exist, the authors establi sh the conditions under which there is also a continuum of mixed strategy equilibria. These are most likely to exist when either the horizon is infinite or the game is symmetric. Copyright 1988 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.

Search, Unemployment, and the Production of Jobs

The authors investigate the performance of the economy when search is required to find employment and when the duration of unemployment varies across sectors. They assume that in one sector factor markets are frictionless, while in the other se ctor idle factors of production must actively search each other out i n order to produce. They focus on how well the economy allocates work ers across sectors and the conditions under which the factor mix with in a sector is correct. The authors demonstrate that in equilibrium t he search sector is too small and its factor intensity is too asymmet ric. Copyright 1987 by Royal Economic Society.

Mathematical Fitting of Modulus-Strain Curves of Poly(ethylene Terephthalate) Industrial Yarns

A mathematical model was developed for fitting the modulus-strain curves of poly(ethylene terephthalate) industrial yams. To develop the model, several asym metric, bell-shaped lines in different combinations were tried out on the modulus- strain curves of no fewer than 90 yarns with widely varying mechanical properties. The model that gave the best fit consists of the sum of three modified Pearson VII lines. The fitting procedure yields a set of 13 parameters by which the modulus-strain curve is fully determined. To illustrate the practical usefulness, some examples are given of relations between process conditions and the calculated modulus-strain pa rameters.