Single-layer one-dimensional nonpolarizing guided-mode resonance filters under normal incidence

We demonstrate that properly designed one-dimensional guided-mode resonance filters (GMRFs) with only one grating layer can exhibit a nonpolarizing resonant filtering effect under normal incidence. A sinusoidal profile nonpolarizing GMRF is realized by photoinduced surface-relief grating formation on thin films of polymer-azobenzene complexes and subsequent atomic layer deposition, showing the feasibility of fabrication of such compact GMRFs.     

Theoretical study of Rb2 in He(N): potential energy surface and Monte Carlo simulations

An analytical potential energy surface for a rigid Rb? in the 3Σ(u)? state interacting with one helium atom based on accurate ab initio computations is proposed. This 2-dimensional potential is used, together with the pair approximation approach, to investigate Rb? attached to small helium clusters He(N) with N = 1-6, 12, and 20 by means of quantum Monte Carlo studies. The limit of large clusters is approximated by a flat helium surface. The relative orientation of the dialkali axis and the helium surface is found to be parallel. Dynamical investigations of the pendular and of the in-plane rotation of the rigid Rb? molecule on the surface are presented.     

Arnowitt–Deser–Misner representation and Hamiltonian analysis of covariant renormalizable gravity

We study the recently proposed Covariant Renormalizable Gravity (CRG), which aims to provide a generally covariant ultraviolet completion of general relativity. We obtain a spacetime decomposed form—an Arnowitt–Deser–Misner (ADM) representation—of the CRG action. The action is found to contain time derivatives of the gravitational fields up to fourth order. Some ways to reduce the order of these time derivatives are considered. The resulting action is analyzed using the Hamiltonian formalism, which was originally adapted for constrained theories by Dirac. It is shown that the theory has a consistent set of constraints. It is, however, found that the theory exhibits four propagating physical degrees of freedom. This is one degree of freedom more than in Hořava–Lifshitz (HL) gravity and two more propagating modes than in general relativity. One extra physical degree of freedom has its origin in the higher order nature of the CRG action. The other extra propagating mode is a consequence of a projectability condition similarly as in HL gravity. Some additional gauge symmetry may need to be introduced in order to get rid of the extra gravitational degrees of freedom.     

Conformational isomerization of formic acid by vibrational excitation at energies below the torsional barrier

Photoinduced conformational isomerization of formic acid has been studied in a low-temperature argon matrix. It is found that conformational isomerization occurs when the photon energy is below the energy barrier for this process. The quantum yield for the process near the top of the barrier is comparable with the quantum yield above the barrier and drops at lower energies. The isomerization takes place via a tunneling mechanism.     

Solid-contact ion-selective electrodes for aromatic cations based on pi-coordinating soft carriers

Ion-selective electrodes (ISEs) based on pi-coordinating carriers were prepared and investigated as potentiometric sensors for aromatic cations, using N-methylpyridinium as a model aromatic cation. Derivatives of tetraphenylborate were studied as charged carriers in plasticized poly(vinyl chloride) membranes. Furthermore, neutral compounds containing pi-coordinating anthryl groups were studied as neutral carriers. Bis(2-ethylhexyl)sebacate (DOS) and 2-nitrophenyl octyl ether (o-NPOE) were used as non-polar and polar plasticizer, respectively. ISEs were constructed by using poly(3,4-ethylenedioxythiophene) (PEDOT) as solid-contact material. Conventional ISEs with internal filling solution were used for comparison. The potentiometric responses of the ISEs were investigated using N-methylpyridinium as primary ion. The results show that the selectivity of the ISEs is influenced significantly by both the plasticizer and the charged carriers, while the neutral carriers studied have only a minor influence on the selectivity. The role of cation-pi interactions between aromatic cations and the membrane components is discussed.     

cis-trans formic acid dimer: experimental observation and improved stability against proton tunneling

We prepared the first cis-trans dimer of formic acid and measured its vibrational spectrum in a low-temperature Ar matrix. This preparation was done by selective vibrational excitation of the trans-trans noncyclic dimer. It was found that the stability of the cis-trans dimer against proton tunneling is strongly improved compared to the monomer, especially at elevated temperatures (>30 K). This surprising phenomenon was explained by differences in dynamical, energetic, and vibrational properties of the dimer and monomer. The obtained results show that the proton tunneling reactions can be strongly modified in the hydrogen-bonded solid network compared to the monomeric species.     

Some problems in automatic process grouping and file consolidation

The purpose of this paper is to define the operations for process grouping and file consolidation, and also the circumstances under which these operations can be applied, with sufficient accuracy so that they could be performed by a computer program used for system design. The usual consolidation of standing files is made in three steps, using precise matrix operations. Concerning the problem of losing many possibilities for later process grouping when consolidating standing files, two solutions are given. The first uses a matrix, which gives information about the relations between the different update versions of the same file. In the second a matrix is used, which gives information about the precedence relations caused by the original relations of the system, to indicate when the change of the execution order of two processes is possible.     

Improvements in diffraction efficiency of gratings and microlenses with continuous relief structures

The fabrication of diffractive optical elements by laser-beam writing or gray-tone technology leads to continuous-relief phase elements. The diffraction efficiency of such elements is limited by the resolution of the process. In this paper, we compare the continuous-relief elements with the multilevel elements fabricated by binary technology. In particular, we will show that for similar sampling resolution of the ideal phase function, the continuous profiles have higher efficiencies than the multilevel profiles if the designed phase modulation is 4π and more.     

Persistence of Simple Substances

In this paper, we argue for a novel three-dimensionalist (3D'ist) solution to the problem of persistence, i.e. cross-temporal identity. We restrict the discussion of persistence to simple substances, which do not have other substances as their parts. The account of simple substances employed in the paper is a trope-nominalist strong nuclear theory (SNT), which develops Peter Simons' trope nominalism. Regarding the distinction between three dimensionalism (3D) and four dimensionalism (4D), we follow Michael Della Rocca's formulation, in which 3D explains persistence in virtue of same entities and 4D in virtue of distinct entities (temporal parts). SNT is a 3D'ist position because it accounts for the persistence of simple substances in virtue of diachronically identical ‘nuclear’ tropes. The nuclear tropes of a simple substance are necessary for it and mutually rigidly dependent but distinct. SNT explains qualitative change by tropes that are contingent to a simple substance. We show that it avoids the standard problems of 3D: temporal relativization of ontic predication, Bradley's regress and coincidence, fission and fusion cases. The temporal relativization is avoided because of the analysis of temporary parts that SNT gives in terms of temporal sub-location, which is atemporal part–whole relation.     

Polymerization of ethylene with new diimine complexes of late transition metals

Three pyridylimine based complexes of Ni^II and Co^II were reacted with methylaluminoxane (MAO) and tested as catalysts in ethylene polymerization. The two nickel catalysts produced mainly methyl branched polymers with good to moderate activity, while the cobalt compound showed only marginal activity. Reaction conditions strongly affect the polymer properties, such as molecular weight, melting temperature, degree of branching, and chain end unsaturation type.