Velocity map imaging spectroscopy of C<inf>2</inf>H^-and C<inf>2</inf>D^-: A benchmark study of vibronic coupling interactions

High-resolution velocity-map imaged photoelectron spectra of the ethynyl anions C2H- and C2D- are measured at photon wavelengths between 355 and 266 nm to investigate the complex interactions between the closely lying X 2ς+ and A 2Π electronic states. An indicative kinetic energy resolution of 0.4%, together with the full angular dependence of the fast electrons, provides a detailed description of the vibronically coupled structure. It is demonstrated that a modest quadratic vibronic coupling model, parameterized by the quasidiabatic ansatz, is sufficient to accurately recreate all the observed vibronic interactions. Simulated spectra are shown to be in excellent agreement with the experimental data, verifying the proposed model and providing a framework that may be used to accurately simulate spectra of larger C2nH monohydride carbon chains. New spectral assignments are supported by experimental electron anisotropy measurements and Dyson orbital calculations

Positive contraction mappings for classical and quantum Schrodinger systems

The classical Schrodinger bridge seeks the most likely probability law for a diffusion process, in path space, that matches marginals at two end points in time; the likelihood is quantified by the relative entropy between the sought law and a prior, and the law dictates a controlled path that abides by the specified marginals. Schrodinger proved that the optimal steering of the density between the two end points is effected by a multiplicative functional transformation of the prior; this transformation represents an automorphism on the space of probability measures and has since been studied by Fortet, Beurling and others. A similar question can be raised for processes evolving in a discrete time and space as well as for processes defined over non-commutative probability spaces. The present paper builds on earlier work by Pavon and Ticozzi and begins with the problem of steering a Markov chain between given marginals. Our approach is based on the Hilbert metric and leads to an alternative proof which, however, is constructive. More specifically, we show that the solution to the Schrodinger bridge is provided by the fixed point of a contractive map. We approach in a similar manner the steering of a quantum system across a quantum channel. We are able to establish existence of quantum transitions that are multiplicative functional transformations of a given Kraus map, but only for the case of uniform marginals. As in the Markov chain case, and for uniform density matrices, the solution of the quantum bridge can be constructed from the fixed point of a certain contractive map. For arbitrary marginal densities, extensive numerical simulations indicate that iteration of a similar map leads to fixed points from which we can construct a quantum bridge. For this general case, however, a proof of convergence remains elusive.Comment: 27 page

Typical support and Sanov large deviations of correlated states

Discrete stationary classical processes as well as quantum lattice states are asymptotically confined to their respective typical support, the exponential growth rate of which is given by the (maximal ergodic) entropy. In the iid case the distinguishability of typical supports can be asymptotically specified by means of the relative entropy, according to Sanov's theorem. We give an extension to the correlated case, referring to the newly introduced class of HP-states.Comment: 29 pages, no figures, references adde

No-Boundary Theta-Sectors in Spatially Flat Quantum Cosmology

Gravitational theta-sectors are investigated in spatially locally homogeneous cosmological models with flat closed spatial surfaces in 2+1 and 3+1 spacetime dimensions. The metric ansatz is kept in its most general form compatible with Hamiltonian minisuperspace dynamics. Nontrivial theta-sectors admitting a semiclassical no-boundary wave function are shown to exist only in 3+1 dimensions, and there only for two spatial topologies. In both cases the spatial surface is nonorientable and the nontrivial no-boundary theta-sector unique. In 2+1 dimensions the nonexistence of nontrivial no-boundary theta-sectors is shown to be of topological origin and thus to transcend both the semiclassical approximation and the minisuperspace ansatz. Relation to the necessary condition given by Hartle and Witt for the existence of no-boundary theta-states is discussed.Comment: 30 p

Renormalized Coupled Cluster Approaches in the Cluster-in-Molecule Framework: Predicting Vertical Electron Binding Energies of the Anionic Water Clusters (H2O)n–

Anionic water clusters are generally considered to be extremely challenging to model using fragmentation approaches due to the diffuse nature of the excess electron distribution. The local correlation coupled cluster (CC) framework cluster-in-molecule (CIM) approach combined with the completely renormalized CR-CC(2,3) method [abbreviated CIM/CR-CC(2,3)] is shown to be a viable alternative for computing the vertical electron binding energies (VEBE). CIM/CR-CC(2,3) with the threshold parameter ζ set to 0.001, as a trade-off between accuracy and computational cost, demonstrates the reliability of predicting the VEBE, with an average percentage error of ∼15% compared to the full ab initio calculation at the same level of theory. The errors are predominantly from the electron correlation energy. The CIM/CR-CC(2,3) approach provides the ease of a black-box type calculation with few threshold parameters to manipulate. The cluster sizes that can be studied by high-level ab initio methods are significantly increased in comparison with full CC calculations. Therefore, the VEBE computed by the CIM/CR-CC(2,3) method can be used as benchmarks for testing model potential approaches in small-to-intermediate-sized water clusters

Development of technology for bakery products of functional purpose using non-traditional raw materials

Good and healthy nutrition is one of the most important and necessary conditions for conservation of life and health of the nation. In recent years in the science of nutrition a new direction - functional nutrition has developed. Functional nutrition products, when used systematically, should have a regulating effect on the macroorganism or certain organs and systems, providing a non-medicamentous correction of their function. Functional food products are intended for the systematic use in diet in all age- groups of healthy population. Consisting of physiologically functional food ingredients they reduce the risk of developing nutritional diseases, preserve and improve health. Physiologically functional food ingredients include biologically active and physiologically valuable ingredients , safe for health, having precise physicochemical characteristics. Their properties have been identified and scientifically justified, and daily intake of food products has been established. These are dietary fiber, vitamins, in particular vitamins-antioxidants, minerals, polyunsaturated fatty acids and their sources, probiotics, prebiotics, and synbiotics. Bakery products were and remain one of the main food products of the population of our country. Thanks to its daily consumption bread is one of the most important food products, the nutritional value of which is of primary importance. It provides more than 50% of the daily energy requirement and up to 75% of the demand for vegetable protein. Therefore, functional nutrition products are of great importance for improving the diet of the population

Photochemistry of (OCS)<inf>n</inf>^- cluster ions

We report the photochemistry of (OCS)n- cluster ions following 395 nm (n=2-28) and 790 nm (n=2-4) excitation. In marked contrast to (CO2)n-, extensive bond breaking and rearrangement is observed. Three types of ionic products are identified: S2-(OCS)k, S-(OCS)k/OCS2-(OCS)k-1, and (OCS)k-. For n<16, 395 nm dissociation is dominated by S2--based fragments, supporting the theoretical prediction of a cluster core with a C2v(OCS)2- dimer structure and covalent C-C and S-S bonds. A shift in the branching ratio in favor of S--based products is observed near n=16, consistent with an opening of the photodissociation pathway of OCS- core-based clusters. These monomer-based cluster ions may coexist with the dimer-based clusters over a range of n, but electron detachment completely dominates photodissociation as long as their vertical electron detachment energy, increasing with addition of each solvent molecule, is less then the photon energy. An (OCS)2- conformer of C2 symmetry with a covalent C-C bond is believed to be responsible for 790 nm dissociation of (OCS)2-, yielding primarily OCS- products. The yield of OCS-, and thus the importance of the C2 form of (OCS)2- cluster core, decreases with increasing n, perhaps due to more favorable solvation of the C2v form of (OCS)2- and/or a solvent-induced increase in the rate of interconversion of conformers. The (OCS)k- products observed in 395 nm photodissociation of the larger (n≥7) clusters are attributed to photofragment caging. Formation and dissociation mechanisms of clusters with different core types are discussed. The photochemical properties of (OCS)n- are compared to those of the isovalent (CO2)n- and (CS2)n- species. © 1998 American Institute of Physics

Photoinitiated decomposition of HNCO near the H؉NCO threshold: Centrifugal barriers and channel competition

The decomposition of jet-cooled HNCO is investigated near the HϩNCO channel threshold ͓D 0 (HϩNCO͒ϭ38 370 cm Ϫ1 ͔. Dissociation to HϩNCO at energies 17-411 cm Ϫ1 above D 0 ͑HϩNCO͒ proceeds on the ground potential energy surface (S 0 ), apparently without a barrier. The rotational state distributions of the NCO(X 2 ⌸ 3/2 ,00 1 0) fragment are well described by phase space theory ͑PST͒, provided that dynamical constraints are included. These constraints are associated with long range ͑4-7 Å͒ centrifugal barriers, which are significant even near threshold because of the small reduced mass of HϩNCO, and result in a fraction of energy deposited in fragment rotation much smaller than predicted by unconstrained PST. The influence of orientation averaging on the attractive, long-range part of the potential is discussed, and it is argued that angular averaging with respect to the center of mass of the rotating polyatomic fragment results in a shift in the effective potential origin, accompanied by an attenuation of the magnitude of the potential compared to its value for fixed H-N distance. Following initial S 1 ( 1 AЉ)←S 0 ( 1 AЈ) excitation and internal conversion to S 0 , HNCO͑S 0 ) decays both via unimolecular decomposition of HϩNCO and intersystem crossing to the dissociative first triplet state, T 1 ͓yielding NH(X 3 ⌺ Ϫ )ϩCO products͔. The competition between the two processes is interrogated by monitoring changes in the relative yields of NCO and NH(X 3 ⌺ Ϫ ) as a function of excitation energy. It is concluded that near D 0 (HϩNCO͒, the S 0 →T 1 intersystem crossing rate is several-fold faster than the HϩNCO unimolecular decomposition rate