Bond charge parameters from integrated infrared intensities

A procedure is outlined to analyze the infrared absorption intensities of fundamental vibration bands in terms of “bond charge parameters”. The method is illustrated for some small C_2v- and C_3v-type molecules: SO₂, NF₃, and PF₃. The values obtained for the “bond charge reorganizations” and “effective bond charges” for SO, NF, and PF bonds are discussed. The method offers the possibility of calculating rotational contributions without the use of a reference molecule.     

An effective procedure to determine corrugation functions from atomic beam-diffraction intensities

A computational method is described, which, starting from given difraction intensities, approaches effectively the best-fit corrugation function $\text{ζ(}\text{R}\text{)}$. Because of the approximations involved, the procedure works well for smooth corrugations with amplitudes not exceeding ～10% of the lattice constant. The method rests on two crucial observations: (i) With the full knowledge of the scattering amplitudes $\text{A}{}_{\mathrm{G}}\text{= ¦A}{}_{\mathrm{G}}\text{¦}\text{exp}\text{(}\text{i}\text{?}{}_{\mathrm{G}}\text{)}$ (absolute values plus phases), the corrugation function can be calculated to a high degree of accuracy from $\text{ζ(}\text{R}\text{) = (2}\text{i}\text{k}{}_{\mathrm{i}}\text{)}{}^{\mathrm{?1}}$ In $\text{¦?ΣA}{}_{\mathrm{G}}\text{exp}\text{(}\text{i}\text{G·R}\text{)¦}$ which is derived easily from the hard corrugated wall scattering (HCWS) equation by approximating $\text{k}{}_{\mathrm{G}}$ by $\text{?}\text{k}{}_{\mathrm{i}}$ ($\text{k}{}_{\mathrm{i}}$ and $\text{k}{}_{\mathrm{G}}$ being the wavevectors of the incoming and diffracted beams, respectively), (ii) With only the $\text{¦A}{}_{\mathrm{G}}\text{¦'s}$ (or intensities) known, approximate solutions of the HCWS equation can be obtained with a rough estimate of the relative phases of only a few intense diffraction beams; the estimate is readily performed by investigating systematically a coarse mesh of phases. In this way, approximate corrugations are found with which a full set of phases can be generated, which allows the calculation of an improved ζ(R); this step is repeated in a loop, until optimum agreement between calculated and given intensities is obtained. The effectiveness of the procedure is demonstrated for three one-dimensional model corrugations described by several Fourier coefficients. The method is finally applied to the case of H₂ diffraction from the quasi-one-dimensional adsorbate corrugation Ni(110) + H(1 × 2).     

Absolute infrared intensities in some metal carbonyls and the charge flux model of the dipole derivatives

The absolute intensities of the four infrared active modes of certain metal carbonyls, M(CO)₄ or M(CO)₆, are analyzed from the point of view of the equilibrium charge-charge flux model of the dipole derivatives. It is shown that the charges obtained from the bending modes, assuming negligible flux for these modes, are apparently identical with those reported by previous authors. However, such charges are much too sensitive to the choice of L matrix (which transforms the normal coordinates to symmetry coordinates) to permit any conclusions. The carbonyl stretching mode implies values of the dipole derivative three- to sixfold greater than in gaseous CO. It seems most reasonable to attribute most of this enhancement to charge flux between the metal and carbon atoms.     

An effective approach for simulating the two-color infrared seekers

Using two-color, in the infrared seekers became a popular technique to achieve an efficient tracking in the existence of countermeasures. Simulating the seeker for getting the target and flares information signals is a critical task, as the more dynamics and robust simulation will help to achieve more robust IRCCM algorithms. In this paper a general method is stated to be simple, effective, dynamics, and independent of the reticle structure.     

Semi-microscopic model for the effective pairing interaction in atomic nuclei

A model has been proposed in which the ab initio effective pairing interaction in atomic nuclei is supplemented by a small phenomenological term containing one parameter universal for all intermediate-mass and heavy nuclei. The neutron and proton pairing gaps have been calculated for several chains of semimagic nuclei; these calculations demonstrate the applicability of this model.     

Integrated infrared intensities of methane

The integrated infrared intensities of the fundamental modes of CH₄ and CD₄ have been measured by the Wilson-Wells-Penner-Weber method. The intensities were found to be 298.1 ± 1.0 and 146.0 ± 2.4 atm^-1 cm^-2 [standard temperature and pressure (STP)] for the ν₃ and ν₄ bands, respectively, of CH₄, and 133.1 ± 3.8 and 84.9 ± 2.8 atm^-1 cm^-2 (STP) for the ν₃ and ν₄ bands, respectively, of CD₄.     

Parametrization of infrared intensities of small molecules and prediction of infrared intensities of large molecules

A quick survey of the main forms of intensity parameters is given, with particular stress on requirements of transferability to other molecules and on physical meaning. It is shown that electrooptical parameters are the most appealing form of parameters for prediction purposes. It is also shown that equilibrium charges and charge fluxes, which can be determined univocally from electrooptical parameters, provide a very simple interpretation of the electrical behavior of molecules and elucidate some of the so-far-unexplained features related to the interpretation of infrared intensities.Published in Zhurnal Prikladnoi Spektroskopii, Vol. 42, No. 2, pp. 265–282, February, 1985.     

An adaptive multi-feature segmentation model for infrared image

Active contour models (ACM) have been extensively applied to image segmentation, conventional region-based active contour models only utilize global or local single feature information to minimize the energy functional to drive the contour evolution. Considering the limitations of original ACMs, an adaptive multi-feature segmentation model is proposed to handle infrared images with blurred boundaries and low contrast. In the proposed model, several essential local statistic features are introduced to construct a multi-feature signed pressure function (MFSPF). In addition, we draw upon the adaptive weight coefficient to modify the level set formulation, which is formed by integrating MFSPF with local statistic features and signed pressure function with global information. Experimental results demonstrate that the proposed method can make up for the inadequacy of the original method and get desirable results in segmenting infrared images.     

Global fitting of line intensities of acetylene molecule in the infrared using the effective operator approach

The method of effective operators has been applied to the global fitting of line intensities of the acetylene molecule in the middle infrared. Simultaneous fittings of recently observed line intensities in the cold and hot bands lying in the 13.6, 7.8, and 5 μm regions have been performed. The eigenfunctions of the effective Hamiltonian developed for the global treatment of the vibration-rotation line positions of acetylene [O.M. Lyulin, V.I. Perevalov, S.A. Tashkun, J.-L. Teffo, in: Leonid N. Sinitsa (Ed.), 13th Symposium and School on High Resolution Molecular Spectroscopy, Proceedings of SPIE, vol. 4063, 2000, pp. 126-133] have been used in the calculations. The sets of effective dipole moment parameters obtained reproduce the observed line intensities within the experimental accuracy. The importance of l-type resonance, responsible for some large differences between intensities of the same lines in subbands having opposite parities, is exhibited and discussed.     

Temperature dependence of effective charge in dipole model of ferroelectrics

Combining the concept of the effective charge in the dipole model with the statistical theory of ferroelectricity proposed previously, the temperature dependence of the effective charge is evaluated numerically for various values of dipole interaction.     

Electrodynamics of effective charge

A portion of the charge induced in an isotropic plasma by an injected charged particle is shown to combine with the particle to form a charged quasi-particle, the effective charge, that is different from the conventional “dressed” charge. The remainder of the induced charge is found in a wake behind the effective charge. Properties of effective charge are described, and the application of this concept to coherent ion acceleration and stopping power is discussed.     

An improved effective liquid drop model for cluster radioactivity

The effective liquid drop model(ELDM) is improved by introducing an accurate nuclear charge radius formula and an analytic expression for assaulting frequency. Within the improved effective liquid drop model(IMELDM), the experimental cluster radioactivity half-lives of the trans-lead region are calculated. It is shown that the accuracy of the IMELDM is improved compared with that of the ELDM. At last, the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead nuc...     

Theoretical framework for quantitatively estimating ultrasound beam intensities using infrared thermography

In the characterization of high-intensity focused ultrasound (HIFU) systems, it is desirable to know the intensity field within a tissue phantom. Infrared (IR) thermography is a potentially useful method for inferring this intensity field from the heating pattern within the phantom. However, IR measurements require an air layer between the phantom and the camera, making inferences about the thermal field in the absence of the air complicated. For example, convection currents can arise in the air layer and distort the measurements relative to the phantom-only situation. Quantitative predictions of intensity fields based upon IR temperature data are also complicated by axial and radial diffusion of heat. In this paper, mathematical expressions are derived for use with IR temperature data acquired at times long enough that noise is a relatively small fraction of the temperature trace, but small enough that convection currents have not yet developed. The relations were applied to simulated IR data sets derived from computed pressure and temperature fields. The simulation was performed in a finite-element geometry involving a HIFU transducer sonicating upward in a phantom toward an air interface, with an IR camera mounted atop an air layer, looking down at the heated interface. It was found that, when compared to the intensity field determined directly from acoustic propagation simulations, intensity profiles could be obtained from the simulated IR temperature data with an accuracy of better than 10%, at pre-focal, focal, and post-focal locations.     

Predicted infrared intensities of diacetylene and 1,3-pentadiyne

The bond polar parameters method has been applied in predicting infrared band intensities for diacetylene and 1,3-pentadiyne using local intensity parameters determined from experimental data for acetylene and propyne. Satisfactory agreement between calculated and observed spectral curves is obtained.     

An effective pumping method for increasing atomic utilization in a compact cold atom clock

We propose a simple pumping method to increase the effective population of cold atoms in the clock state and investigate the factors which affect the pumping efficiency in cold atom systems. We report the theory and demonstrate the corresponding experiment in an ⁸⁷Rb integrating sphere cold atom clock. The experimental results show that the population of cold atoms in the Zeeman sublevel |F=2, m_F=0> is approximately 1.62 times that of the result using optical pumping alone. This method can also be applied to increase the effective population in any one of the target Zeeman sublevels in other cold atom systems.     

Effects of charge density waves on bragg peak intensities

The theory of diffraction from a modulated lattice predicts, in addition to satellite formation, that the main reflections themselves are affected. We observed this effect in TaS₂, across the polymorphic transition 1T₁ ? 1T₂ at T₀ = 80° C.