[en] Scaling of the exact function for the number of intramolecular nonbonded contacts in a single maximally compact linear homopolymer on hypercubic lattices is determined as a function of number N of monomers and dimension d. A representative maximally compact structure is designed and an exact recursive expression for the maximum number m_max of contacts is derived from that design. The equivalent nonrecursive expression yields the asymptotic scaling of m_max as (d-1)N-dN^Δ+1, with Δ=(d-1)/d. Implications in polymer and protein studies are discussed. copyright 1999 The American Physical Society

[en] Materials containing the anioinic species: CuX emit in the solid state. Their emission has been characterized by a change in wavelength of maximum emission with lowering of temperature. The change in color may be explained by a rearrangement between CuX₂- and Cu₂I₄- forms each of which is responsible for one of the two wavelengths observed. Complexes of the type CuI₂ crystallize in different space groups and with different crystallographic symmetry elements have been observed. The visible emission from these solid complexes may arise only from metal-halide interactions. The elimination of metal to metal, metal to ligand charge transfer, and anion-solvent interaction permits the examination of the influence of crystallographic symmetry as a factor in emission behavior. Ab initio calculations support the assignment of emission and excitation transitions. The examination of the visible emission characteristics a series of CuX₂ complexes in which XI, Br and Cl, permits the evaluation of the influence of halide identity upon electronic transitions

[en] An experimental study has been carried out of the kinetics of formation of singlet oxygen molecules in the a¹Δ_g state in a decaying oxygen-nitrogen plasma. The oxygen-nitrogen medium at pressures of 10 and 20 torr was excited by rf discharges. The mass fraction of oxygen varied from 2.5 to 100%. The O₂(a¹Δ_g) concentration was determined from the spontaneous emission at wavelength λ = 1268 nm. The experimental device could be operated in two ways: either by exciting a previously prepared nitrogen-oxygen mixture with an rf discharge or by independently using rf discharges to excite streams of nitrogen and oxygen, which were then mixed. The experiments showed that there exists an efficient process for transmitting vibrational energy of the nitrogen molecules to the metastable electron state a¹Δ_g of the oxygen molecules in which this mechanism acts through intermediate strong excitation of the vibrational modes of ozone. Nonmonatomic quenching of O₂(a¹Δ_g) by ozone has been observed, which is also associated with vibrational excitation of O₃. It has been shown experimentally that the O₃(vib) molecules form through interaction with vibrationally excited nitrogen molecules and in three-body reactions converting atomic oxygen to ozone. These results can be important for understanding the properties of ozone generation and the excitation of oxygen states in plasma-chemical devices of various types, and also for interpreting experimental data in the physics of the upper atmosphere. 17 refs., 7 figs

[en] In recent years a new direction of research has emerged at the boundary between elementary particle physics and atomic spectroscopy: the investigation of weak interactions by optical methods. These studies have led to the discovery of parity nonconservation in atomic transitions, which has served as one of the first decisive confirmations of the unified model of electroweak interactions. This book offers a coherent picture of a subject which spans a wide range of areas of physics, from elementary particles and nuclei to atoms and molecules. The author considers the effects of space-inversion and time-reversed violation in atoms, molecules and condensed matter. He has produced a work for theoreticians and experimentalists alike, specializing in atomic, nuclear, and elementary particle physics. Abstracts have been prepared for each of the 13 chapters of this book

[en] The author touches on a few topics of recent interest in the area of atomic and molecular physics research. He begins by noting that this old field is working on very new and exciting problems today, almost all of which would not even by found in subject surveys of only three years ago. He discusses work in cavily quantum electrodynamics, the manipulation of atoms with light, chaos and quantum mechanics, and advances in trapped ion research. In the last area, work has varied from precision experiments on single trapped ions, to collective effects in small numbers of trapped ions, to plasma behavior for even larger ion densities. Traps have even been able to capture anti-protons

[en] The physical and chemical properties of large carbon clusters, C_n (n >40), have been studied extensively over the past six years. The spherical nature of these clusters has been debated and inferred from both experimental and theoretical studies until the recent isolation and subsequent spectroscopic identification of bulk C₆₀ and C₇₀. Although the n = 60 and 70 cluster ions are anomalously abundant (magic numbers) in the mass spectra and are proposed to be highly symmetric species, the other magic number clusters have yet to be isolated. In an attempted to further the understanding of the physical properties of these large carbon clusters, we have determined the ionization potentials (IPs) by charge transfer bracketing techniques from ions generated both by direct laser vaporization (DLV) of graphite and by electron ionization (EI) of the bulk vapor of C₆₀ and C₇₀. Electron ionization of the bulk vapor has also permitted the determination of the second IPs of several of the clusters (n = 56, 60 and 70). Additionally, the authors of this paper have investigated the collision of singly and doubly charged C₆₀ ions with surfaces in an attempt to determine whether surface-induced dissociation (SID) can be used to characterize the properties of these species

[en] In this paper the solution of large sparse linear systems of algebraic equations arising from the discretization of coupled Boltzmann partial integro-differential equations, which model ion-ion recombination processes in dense gases, is discussed. The advantages and limitations of various representations of these equations is provided. A detailed analysis is given of the derivation and structure of the coefficient matrix A of the resultant algebraic equations. The need for preconditioning the algebraic equations through the calculation of the condition number of the matrix A is highlighted. Approximate methods of computing thermolecular recombination rate coefficients via the Debye-Smoluchowski equation and diffusion models in energy space are also briefly discussed

[en] This paper reports on the molecular information needed to calculate any macroscopic equilibrium property, such as pressure or free energy, using standard statistical thermodynamic relationship. Various transport properties, such as the self-diffusion coefficient of small electrolyte ions, and spectroscopic variables, such as the average NMR relaxation rate of probe nuclei in a solute species, also can be calculated from pertinent radial distribution functions. Thus, for theoretical calculations of the measurable properties of liquid solutions, radial distribution functions provide a basis whose broad utility resembles that of the wave function in quantum mechanical calculations. However, radial distribution functions are not the ultimate origin, but rather the most useful and general microscopic counterparts, of macroscopic properties that also reflect interparticle interactions

[en] A semi-empirical procedure is introduced by means of which the like and unlike interaction parameters of an intermolecular potential of the form L.J. (n-6) can be obtained from the temperature dependence of the viscosity of pure gases and their binary mixtures. The potentials with n=7 to 90 are considered. The procedure is tested and proved successful for the Ar - Kr system. It is found that the best potential representing the interaction of this system is the L.J. (11.5-6). It reproduces the experimental results satisfactorily to within 4%

[en] Short communication