Electronic structure of the 4 d transition metal carbides: dispersed fluorsecence spectroscopy of MoC, RuC, and PdC

Journal ArticleDispersed fluorescence studies of the diatomic molecules MoC, RuC, and PdC are reported. New states identified in MoC and RuC are the [...]2??12??, ?,??? states and the [...]2??12??, ??? state, respectively. Five states are observed by dispersed fluorescence in PdC. The ground state is found to be [...]2??12??, ??+, with the [...]2?? 12??6rr?, ?II? manifold of states lying about 2500 cm-? above the ground state. The [17.9]?=1 state of PdC is also identified as [...]??12??13??, ??+(?=1), corroborating recent results of resonant two photon ionization spectroscopy studies. The spin-orbit interactions of these molecules are analyzed to deduce the composition of the molecular orbitals, and comparisons are made to ab initio theory when possible. An examination of the trends in bond energy, bond length, and vibrational frequency among the 4d transition metal carbides is also provided

Electronic structure of the 4d transition metal carbides: dispersed fluorescence spectroscopy of MoC, RuC, and PdC

Journal ArticleDispersed fluorescence studies of the diatomic molecules MoC, RuC, and PdC are reported. New states identified in MoC and RuC are the [...]2?112?1, 3,1?2 states and the [...]2? 312?1, 1?2 state, respectively. Five states re observed by dispersed fluorescence in PdC. The ground state is found to be [ ...]2? 412?2, 1?+, with the [ ...]2? 412?16rr1, 3II? manifold of states lying about 2500 cm-1 above the ground state. The [17.9]?=1 state of PdC is also identified as [...]2? 412?113?1, ?+(?=1), corroborating recent results of resonant two photon ionization spectroscopy studies. The spin-orbit interactions of these molecules are analyzed to deduce the composition of the molecular orbitals, and comparisons are made to ab initio theory when possible. An examination of the trends in bond energy, bond length, and vibrational frequency among the 4d transition metal carbides is also provided

Renormalized One-loop Theory of Correlations in Disordered Diblock Copolymers

A renormalized one-loop theory (ROL) is used to calculate corrections to the random phase approximation (RPA) for the structure factor \Sc(q) in disordered diblock copolymer melts. Predictions are given for the peak intensity $S(q^{\star})$, peak position $q^{\star}$, and single-chain statistics for symmetric and asymmetric copolymers as functions of $\chi N$, where $\chi$ is the Flory-Huggins interaction parameter and $N$ is the degree of polymerization. The ROL and Fredrickson-Helfand (FH) theories are found to yield asymptotically equivalent results for the dependence of the peak intensity $S(q^{\star})$ upon $\chi N$ for symmetric diblock copolymers in the limit of strong scattering, or large $\chi N$, but yield qualitatively different predictions for symmetric copolymers far from the ODT and for asymmetric copolymers. The ROL theory predicts a suppression of $S(q^\star)$ and a decrease of $q^{\star}$ for large values of $\chi N$, relative to the RPA predictions, but an enhancement of $S(q^{\star})$ and an increase in $q^{\star}$ for small $\chi N$ ($\chi N < 5$). By separating intra- and inter-molecular contributions to $S^{-1}(q)$, we show that the decrease in $q^{\star}$ near the ODT is caused by the $q$ dependence of the intermolecular direct correlation function, and is unrelated to any change in single-chain statistics, but that the increase in $q^{\star}$ at small values of $\chi N$ is a result of non-Gaussian single-chain statistics.Comment: 16 pages, 13 figures, submitted to J. Chem. Phy

Zoom invariant vision of figural shape: The mathematics of cores

Believing that figural zoom invariance and the cross-figural boundary linking implied by medial loci are important aspects of object shape, we present the mathematics of and algorithms for the extraction of medial loci directly from image intensities. The medial loci called cores are defined as generalized maxima in scale space of a form of medial information that is invariant to translation, rotation, and in particular, zoom. These loci are very insensitive to image disturbances, in strong contrast to previously available medial loci, as demonstrated in a companion paper. Core-related geometric properties and image object representations are laid out which, together with the aforementioned insensitivities, allow the core to be used effectively for a variety of image analysis objectives.

Renormalization of the one-loop theory of fluctuations in polymer blends and diblock copolymer melts

Attempts to use coarse-grained molecular theories to calculate corrections to the random-phase approximation (RPA) for correlations in polymer mixtures have been plagued by an unwanted sensitivity to the value of an arbitrary cutoff length, {\it i.e.}, by an ultraviolet (UV) divergence. We analyze the UV divergence of the inverse structure factor $S^{-1}(k)$ predicted by a `one-loop' approximation similar to that used in several previous studies. We consider both miscible homopolymer blends and disordered diblock copolymer melts. We show, in both cases, that all UV divergent contributions can be absorbed into a renormalization of the values of the phenomenological parameters of a generalized self-consistent field theory (SCFT). This observation allows the construction of a UV convergent theory of corrections to SCFT phenomenology. The UV-divergent one-loop contribution to $S^{-1}(k)$ are shown to be the sum of: (i) a $k$-independent contribution that arises from a renormalization of the effective $\chi$ parameter, (ii) a $k$-dependent contribution that arises from a renormalization of monomer statistical segment lengths, (iii) a contribution proportional to $k^{2}$ that arises from a square-gradient contribution to the one-loop fluctuation free energy, and (iv) a $k$-dependent contribution that is inversely proportional to the degree of polymerization, which arises from local perturbations in fluid structure near chain ends and near junctions between blocks in block copolymers.Comment: 35 pages, 2 figure

Supersymmetric Biorthogonal Quantum Systems

We discuss supersymmetric biorthogonal systems, with emphasis given to the periodic solutions that occur at spectral singularities of PT symmetric models. For these periodic solutions, the dual functions are associated polynomials that obey inhomogeneous equations. We construct in detail some explicit examples for the supersymmetric pairs of potentials V_{+/-}(z) = -U(z)^2 +/- z(d/(dz))U(z) where U(z) = \sum_{k>0}u_{k}z^{k}. In particular, we consider the cases generated by U(z) = z and z/(1-z). We also briefly consider the effects of magnetic vector potentials on the partition functions of these systems.Comment: Changes are made to conform to the published version. In particular, some errors are corrected on pp 12-1

Public Health Disaster Research: Surveying the Field, Defining its Future

Disaster medicine and public health preparedness are commonly perceived as subfields of the larger fields of medicine and public health rather than being recognized as an emerging academic field embracing all of the disciplines that contribute to effective disaster response. As such, they serve as appropriate subjects for multidisciplinary work in the social sciences, whether it is a sociological analysis of mass behavior during a disaster, psychological studies of the willingness to work of various workforces, or organizational theory or network analyses applied to ad hoc disaster coalitions. Laboratory sciences and bioinformatics contribute as well to the development of new treatment modalities, medical products, and surveillance technologies. As is true in the broader medical and public health fields, much of the work is empirical and evaluative. In this article, the authors survey the literature in the field and suggest that broader, more ecologically based research is needed

A current-voltage model for Schottky-barrier graphene based transistors

A low complexity computational model of the current-voltage characteristics for graphene nano-ribbon (GNR) field effect transistors (FET), able to simulate a hundred of points in few seconds using a PC, is presented. For quantum capacitance controlled devices, self-consistent calculations of the electrostatic potential can be skipped. Instead, analytical closed-form electrostatic potential from Laplace's equation yields accurate results compared with that obtained by self-consistent Non-Equilibrium Green's Functions (NEGF) method. The model includes both tunnelling current through the Schottky barrier (SB) at the contact interfaces and thermionic current above the barrier, properly capturing the effect of arbitrary physical and electrical parameters.Comment: 8 pages, 4 figure

Aquatic Insects of Upper Three Runs Creek, Savannah River Plant, South Carolina. Part II: Diptera

As discussed in detail in Part I of this series (Morse et al. 1980), aquatic insects were collected biweekly from six locations on Upper Three Runs Creek, Savannah River Plant near Aiken, South Carolina, from September 1976 through August 1977, using light traps and semi-quantitative benthic sampling methods. See part I (Morse et al. 1980) for site and habitat descriptions and for a discussion of the methods used. In that publication, faunistic results were provided for all insect taxa except Diptera and relative abundance data for all but Diptera and non-dryopoid Coleoptera