A new approach to identifying chemical states,comprising combined use of Auger and photoelectron lines

In the course of the last few years experience has been gained indicating the kind of instrument and the kinds of techniques most useful for examining     

A new approach to peratization technique

The usual method of peratization technique is to expand scattering lengthA(a) in Born series in powers of the coupling constantg. In this paper a new approach to the peratization technique has been discussed starting with the standard equation for the scattering length. As an application of the theory developed, the cases of inverse fourth power and a logarithmic singular potentials have been discussed.     

A new approach to bonding in transition metal clusters

The idea that the molecular orbitals of a cluster of atoms can be usefully classified according to their nodal structure, so that the energy increases with the number of nodes, is quantified and shown to apply in its usual form only to molecular orbitals constructed from atomic σ orbitals. The method is extended to deal with atomic π and δ orbitals by the use of vector and tensor surface harmonics respectively. In all cases the orbitals can be classified approximately in terms of angular momentum quantum numbers l and m, but in the π and δ cases there are two orbitals, with different parity, for each lm, and the energy is determined primarily by the parity. The method provides a classification scheme and an approximate energy ordering which does not depend on any point-group symmetry that the cluster may have, and therefore provides a useful framework for discussion of the bonding in cluster compounds such as the boron hydrides and the transition metal cluster carbonyls.     

Auger lineshape analysis as a tool to study surface reactions: kinetics of the dissociation of NO on Rh(110)

We present a new method for following the kinetics of the dissociation of chemisorbed molecules, by Auger electron spectroscopy (AES) in the pulse counting mode. By following the time evolution of the Auger lineshape, it is possible to quantify the relative weight of the dissociated and undissociated chemisorbed species as a function of time. As an example, we have applied the method to the case of NO chemisorbed on rhodium (110). The high signal to noise ratio which can be obtained by AES in the pulse counting mode makes it possible to measure the kinetics with good accuracy, without affecting the reaction.     

Excitonic molecules: A possible new form of chemical bonding

If a band edge has N equivalent minima in the Brillouin zone, it is possible consistent with the exclusion principle to place 2N identical electrons in the same molecular orbital. This theorem suggest the possible stability of exciton molecular complexes, (exc)₈ in Ge and (exc)₁₂ in Si.     

Back-to-back substrate wafer bonding: A new approach to the fabrication of double-side coated wafers

We present a novel method for fabrication of double side coated wafers by back-to-back Direct Wafer Bonding (DWB). Two 3 inch sapphire wafers (R-cut) were coated each with YBaCu O by laser ablation on one side. The wafers were then directly bonded with their uncoated sides together in a microcleanroom. Subsequent heating increased the bond energy up to energies sufficient for fabrication of hybrid devices working at cryogenic temperatures. TEM cross sections reveal direct contact of the two sapphire lattices. Received: 9 October 1996 / Accepted: 4 November 1996     

Evidence of extended fine structures in the Auger spectra: A new approach for surface structural studies

We report for the first time on extended fine structures which we have observed above core-valence-valence Auger transitions on Cu and Co samples. We interpret these oscillating structures as originated from the same interference process which produces extended fine structures observed in the x ray absorption spectra (EXAFS). Using the same EXAFS analysis procedure, we deduce from the extended fine Auger structures (hereafter called EXFAS) the radial atomic distribution F(R) of Cu and Co samples. An excellent agreement is found as compared with results from synchrotron radiation EXAFS.     

A new method to study the crystallization or chemical reaction kinetics using thermal analysis technique

In this work, a new method to study the transformation kinetics is introduced. With this method, the activation energy, E_c, for crystallization (phase transition or chemical reaction), the pre-exponential coefficient of effective overall reaction rate, k_o, and the reaction order, n, can be determined. No approximation has been used in this method. This method can be used for isothermal and non-isothermal study. It is deduced from Avrami's equation without any approximation. This new method has been tested to study the amorphous-crystalline transformation kinetics under isothermal and non-isothermal conditions in the context of glassy selenium. The source of error is discussed. The calculated values of E_c, under isothermal and non-isothermal conditions are 75.3±2.5 and 79.4±2.3 kJ/mol, respectively. The predominant crystallization mechanism of the amorphous phase of glassy selenium in isothermal or non-isothermal conditions is one-dimensional growth. The deduced values of k_o were found to be 19.4±0.9 and 20.8±0.7 s⁻¹ for isothermal and non-isothermal conditions, respectively. Resulting values of the parameter, n, are compared with values obtained from other known methods used to study the reaction kinetics in thermal analyses. The difference in the results obtained with this method and the results obtained with other known methods is acceptable or lie within the experimental error range.     

The use of Raman spectroscopy as a probe for the intermolecular bonding in crystalline tetraphosphorus trisulphide

The temperature and pressure dependences of the internal and external first-order Raman-active phonons of crystalline α-P₄S₃ are shown to provide a sensitive probe of the intermolecular bonding. Comparison with a similar study of α-P₄Se₃ leads to the conclusion that while intra-intermolecular coupling is present, it is weaker in crystalline α-P₄S₃. Unlike α-P₄Se₃, no rigid layer mode is observed nor is there any softening of the A₁ mode at 440 cm⁻¹ analogous to the 361 cm⁻¹ soft mode of α-P₄Se₃. Weak intra-intermolecular coupling is also supported by an analysis of the implicit-explicit contributions to the observed temperature coefficients. A pressure dependent increase in the intensity of the A₁ mode at 440 cm⁻¹ is compared to similar pressure dependent changes in intensity for phonons in other inorganic molecular solids.     

A new method for the characterization of chemical libraries – solely by HPLC retention times

A method has been developed for the assignment of HPLC peaks to their corresponding compounds in libraries of single compounds (parallel syntheses). The basis of the new method is the correlation of the product retention times with the different substituents in the variable positions of the molecule. The correlation is performed automatically by a new algorithm which is part of the computer program LIBFINDER. This practical, easy-to-use tool accelerates the analysis, characterization and purification of chemical libraries, without the need for expensive HPLC-MS equipment.     

Voigt lineshape function as a solution of the parabolic partial differential equation

The goal of this paper is to show that the Voigt function may be found as a solution of a parabolic partial differential equation, like the heat conduction equation or other diffusion equations. A square of the Gaussian half-width of the Voigt function plays the role of ‘time’ and initial conditions are determined by a Lorentz function. Some questions concerning the practical application of the numerical grid methods for the calculation of the Voigt function are discussed. It is shown, that in some cases the offered calculation algorithm can be both faster and more accurate than other known algorithms.     

Quantum tomography as a new approach to simulating quantum processes

A new method is proposed for ab initio calculations of nonstationary quantum processes on the basis of a probability representation of quantum mechanics with the help of a positive definite function (quantum tomogram). The essence of the method is that an ensemble of trajectories associated with the characteristics of the evolution equation for the quantum tomogram is considered in the space where the quantum tomogram is defined. The method is applied for detailed analysis of transient tunneling of a wave packet. The results are in good agreement with the exact numerical solution to the Schrödinger equation for this system. The probability density distributions are obtained in the coordinate and momentum spaces at consecutive instances. For transient tunneling of a wave packet, the probability of penetration behind the barrier and the time of tunneling are calculated as functions of the initial energy.     

A new approach to a global fit of the CKM matrix

We report on a new approach to a global CKM matrix analysis taking into account most recent experimental and theoretical results. The statistical framework (Rfit) developed in this paper advocates frequentist statistics. Other approaches, such as Bayesian statistics or the 95% CL scan method are also discussed. We emphasize the distinction of a model testing and a model dependent, metrological phase in which the various parameters of the theory are estimated. Measurements and theoretical parameters entering the global fit are thoroughly discussed, in particular with respect to their theoretical uncertainties. Graphical results for confidence levels are drawn in various one and two-dimensional parameter spaces. Numerical results are provided for all relevant CKM parameterizations, the CKM elements and theoretical input parameters. Predictions for branching ratios of rare K and B meson decays are obtained. A simple, predictive SUSY extension of the Standard Model is discussed. Received: 18 April 2001 / Published online: 10 August 2001     

A new formulation for the bethe approach to lattice statistics

An improved mathematical treatment is given for the approximate statistics of the Ising problem based on configurations of local Bethe clusters. The essential step in the development is to write the configuration probability for the Bethe cluster in terms of the probabilities for subclusters. Exact statistical mechanical results are used to interrelate the probabilities. The technique is illustrated first for a simple ferromagnetic lattice and then applied to the order-disorder problems of binary and ternary alloys on the face centered cubic lattice. In each ease the final equations which need solution are derived by strictly algebraic means. The improvement in mathematical treatment is such that these equations are identical with high order approximations of the very different cluster variation method.     

A new approach to the Einstein-Podolsky-Rosen paradox

Some new aspects of the EPR paradox are considered. We first show that the authors' argument, leading to the conclusion that quantum theory is incomplete, is based on a tacit assumption that may be questioned. We then investigate the non-local features of the EPR setup and point out an interesting connection between the nonlocality involved in the quantum correlations of pairs of particles and that of a single particle in quantum theory.     

A new approach to the Efinger model for a nonlinear quantum theory for gravitating particles

A general solution is obtained for a model of a nonlinear quantum theory for gravitating particles proposed by H. Efinger. The solution procedure is easily generalized to space-time or stochastic formulations.     

A systems approach to the characterization of rough ground

A novel method for modelling rough surfaces as the output of linear filters operating on white noise in the spatial domain is proposed. These “systems” models may then be utilized in certain analytical methods proposed by the authors, which are not described herein but have been reported in full elsewhere [1, 2] to calculate the non-stationary response of vehicles moving on rough ground with variable velocity. Either time variable covariance or evolutionary spectra of response may be obtained by the method. Here, justification is provided for the use of such models and a method of estimating their parameters via Maximum Entropy Spectral Analysis—a method well suited to this particular problem—is discussed.     

Ni2分子结构和分子轨道密度(DMO)的成键贡献

用密度泛函(B3P86/6-311g*)方法研究了Ni2分子结构和势能函数.结果表明基态Ni2为5Πg,平衡间距为Re=0.223 196 nm,离解能为1.851 16 eV.定义了分子轨道密度(DMO, density of molecular orbital)并研究了镍双原子分子的s, p, d, f的DMO对成键的贡献,为进一步研究金属的态密度提供了有益的参考价值.     

SIMS as a subnanometer probe: A new tool for chemical profile analysis of grafted molecules

The complexity of modern engineered surfaces requires the development of very powerful methods to analyze and characterize them. We demonstrate that it is possible to obtain chemical information about the skeleton of organic molecules constituting SAMs grafted on a silicon surface by using a new type of SIMS method. A profile can be achieved by the investigation of the temporal variation of secondary ion intensities that correspond to the fractional parts of the molecule constituting the SAMs. The equivalent ablation rate is less than 0.5 nm/min.