Differential Scattering Cross Sections Research Articles

Imaging the Ion-Molecule Reaction Dynamics of O- + CD4.

While neutral reactions involved in methane oxidation have been intensively studied, much less information is known about the reaction dynamics of the oxygen radical anion with methane. Here, we study the scattering dynamics of this anion-molecule reaction using crossed-beam velocity map imaging with deuterated methane. Differential scattering cross sections for the deuterium abstraction channel have been determined at relative collision energies between 0.2 and 1.5 eV and ab initio calculations of the important stationary points along the reaction pathway have been performed. At lower collision energies, direct backscattering and indirect complex-mediated reaction dynamics are observed, whereas at higher energies, sideways deuterium stripping dominates the reaction. Above 0.7 eV collision energy, a suppressed cross section is observed at low product ion velocities, which is likely caused by the endoergic pathway of combined deuteron/deuterium transfer, forming heavy water. The measured product internal energy is attributed mainly to the low-lying deformation and out-of-plane bending vibrations of the methyl radical product. The results are compared with a previous crossed-beam result for the reaction of oxygen anions with nondeuterated ̧methane and with the related neutral-neutral reactions, showing similar dynamics and qualitative agreement.

Scattering by harmonically trapped 2D quantum gas near and around the critical regime

In this article, we analytically explore the quantum phenomena of scattering by harmonically trapped 2D quantum gases. We show the temperature’s dependence on the differential scattering cross-section (DSC) near and around the critical transition regime for both particle and light scattering cases separately. For the particle scattering case, we consider scatterers with quantized bound motion in a harmonic trap. Our findings on the structure factor for light scattering give phase transition phenomena for 2D bosonic atoms and the thermal behavior of the system. This result has practical significance for recent experimental setups such as in situ image analysis and bosonic simulations. Finally, we show the temperature-dependent refractive index for a 2D harmonically trapped bosonic medium. This parameter is important in neutron scattering experiments.

Dirac spinor scattering states with positive‐energy in rotating spheroid models

AbstractThere are many rotating spheroids in the universe, and many astronomers and physicists have used theoretical methods to study the characteristics of stellar gravity since Newton's time. This paper derives the solutions of eight scattering states ,, and for the Dirac equation with positive‐energy , and establishes the relationship between the differential scattering cross section and the stellar density . It is found that: (1) For the eight scattering states, their average scattering cross‐sections are proportional to , and depend on the star's radius, and the higher the stellar density , the greater the sensitivity of to the change of ; (2) For the four scattering states , their average scattering amplitudes and depend on the mass of the particles; while for the other four scattering states , , then and are independent of . This study links the gravitational characteristics of stars with the scattering cross section, creating a new method for studying the gravitational characteristics, which helps to reveal the mystery of the gravity of rotating ellipsoidal stars.

Ta+ and Nb+ + CO2: intersystem crossing in ion-molecule reactions.

The reactions of Ta+ and Nb+ with CO2 proceed only by a highly efficient oxygen atom transfer reaction to the respective oxide at room temperature in the gas phase. Although the product spin states are not determined, thermochemistry dictates that they must be different from ground state quintet Ta+ and Nb+, implying that intersystem crossing (ISC) has occurred. Recent reactive scattering experiments found dominant indirect dynamics for the reaction with Ta+ hinting at a bottleneck along the reaction path. The question on the nature of the bottleneck, whether it involves a crossing point or a transition state, could not be finally answered because theory located both close to each other. Here, we aim at shedding further light onto the impact of intersystem crossing on the reaction dynamics and ultimately the reactivity of transition metal ion reactions in the gas phase. We employ a combination of thermal kinetics for Ta+ and Nb+ with CO2 using a selected-ion flow tube (SIFT) apparatus and differential scattering cross sections for Nb+ + CO2 from crossed-beam velocity map imaging. The reaction with niobium again shows dominant indirect dynamics and in general very similar dynamics compared to Ta+ + CO2. At thermal energies, both reactions show sub-collisional rate constants with small negative temperature dependencies. Experiments are complemented by high level quantum chemical calculations of the minimum energy pathway. Statistical modelling well-reproduces the experimental thermal rate constants, and suggests that the Nb+ reaction is rate-limited by the intersystem crossing at thermal energies.

Total and Double Differential Scattering Cross-Section Measurements of Isotropic Graphite

Total and Double Differential Scattering Cross-Section Measurements of Isotropic Graphite

Analysis of Ca+(2S) + HD (v0 = 0, j0 = 0) → CaH+/CaD+ + D/H reaction dynamics using time-dependent wave packet method

Using the time-dependent wave packet method on a newly reported potential energy surface, the reaction channels of Ca+(2S) + HD (v0 = 0, j0 = 0) → CaH+/CaD+ + D/H were investigated in the collision energy range of 2.3 eV and 4.0 eV. Our analysis commenced with an investigation of the integral and differential scattering cross sections, as well as the reaction probabilities for both reaction channels. The results reveal that the CaH+ + D reaction channel plays a primary role which is consistent with experimental results. The complex forming mechanism and direct-abstraction reaction mechanism exist in this reaction process.

Differential scattering cross section of the non-Abelian Aharonov-Bohm effect in multiband systems

Differential scattering cross section of the non-Abelian Aharonov-Bohm effect in multiband systems

Low and intermediate energy cross section analysis of p-p and p-d elastic scattering using modified phase amplitude method for electromagnetic distorted nuclear interaction

The traditional phase function method is regarded as a resourceful tool for computing scattering phase shifts for quantum mechanical potential scattering involving local interactions. For the local plus a nonlocal potential the conventional phase function method does not hold good. In such a situation one has to modify it. The modified variable phase method is adapted here to treat the Manning-Rosen (MR) plus Graz nonlocal separable potential for constructing an exact expression for the phase function with rigorous inclusion of the electromagnetic effect. The merit of our analytical result is demonstrated by computing elastic scattering phase parameters and differential scattering cross sections for proton-proton (p − p) and proton-deuteron (p − d) systems which are in sensible agreement with previous works.

On quantitative off-axis Scanning Transmission Ion Microscopy (STIM)

Spurred by a need to determine major (C, H, N and O) contents in biological tissue sections, a formalism for quantitative off-axis Scanning Transmission Ion Microscopy (OA-STIM) has been established. This can be used with, or without, simultaneous Elastic Backscattering Spectroscopy (EBS) to provide quantitative major element composition and thickness information. As part of the work, an empirical predictor with one free parameter for the proton–proton differential scattering cross section was implemented. The predictor values were in extremely close agreement with high accuracy literature data. For 2 MeV p–12C elastic scattering at forward angles ≤45°an interpolation procedure was used to determine the relative deviations from the Rutherford cross sections were determined to be ≤6.4%. The interpolation was based on a Coulomb field, angular momentum quantum number and nuclear structure dependent nuclear penetration factor. Finally, the quantitative combination of simultaneous OA-STIM and EBS data is discussed.

Regge pole description of scattering by dirty black holes

We study the problem of plane monochromatic scalar waves impinging upon a Schwarzschild dirty black hole -- a Schwarzschild black hole surrounded by a thin spherical shell of matter -- using the complex angular momentum approach. We first recall general results concerning the differential scattering cross section in the classical limit through a null geodesic analysis by exploring different configurations of the shell. In particular, we show that dirty black hole spacetimes may exhibit various critical effects for geometrical optics. We compute the Regge pole spectrum for various shell configurations and show that it exhibits two or three distinct branches of poles, labelled inner surface waves, broad resonances and outer surface waves. In the latter, two sub-families have been identified, the surface waves associated with the outer light-ring and the creeping modes associated with the surface of the shell. We show, using WKB analysis, that the position of the shell sets the real part of the broad resonances while its energy-momentum and the discontinuity of the potential at the shell's surface set their imaginary part. Next, we provide the complex angular momentum representation of the differential scattering cross section and examine the role of the different Regge pole branches. We compute the differential scattering cross section for various configurations at several frequencies and show a very good agreement with the partial-wave calculations. Finally, we highlight the role of the critical effects, i.e., orbiting, glory, grazing and rainbow scattering, and their impact on the differential scattering cross section.

What Is the Gravitational Field of a Mass in a Spatially Nonlocal Quantum Superposition?

The study of the gravitational field produced by a spatially nonlocal, superposed quantum state of a massive particle is an interesting and active area of research. One outstanding issue is whether the gravitational field behaves like the classical superposition of the gravitational field of two particles separated by a spatial distance with half the mass at each position. Alternatively, does the gravitational field behave as a quantum superposition with a far more interesting and subtle behavior than a simple classical superposition? Quantum field theory is ideally suited to probe exactly this kind of question. We study the scattering of a massless scalar on a spatially nonlocal quantum superposition of a massive particle. We compute the differential scattering cross section corresponding to one-graviton exchange. We find that the scattering cross section disagrees with the Newton-Schrödinger picture of potential scattering from two localized sources with half the mass at each source. This suggests that experimental observation of gravitational scattering could inform the viability of the semiclassical treatment of the gravitational field, as in the Newton-Schrödinger description, vs the fully quantum mechanical treatment adopted here. We comment on the experimental feasibility of observing such effects in systems with many particles such as Bose-Einstein condensates.

Analysis of elastic scattering of 6Li by 90Zr near Coulomb barrier

We use a phenomenological optical potential constructed in consideration of a versatile potential developed by Joseph N. Ginocchio. The optical potential uses less number of energy-dependent parameters to analyse nuclear scattering data. We study the ratios of elastic to Rutherford differential scattering cross sections of the system 6Li + 90Zr at various energies, namely, 10.19, 11.11, 12.07, 13.95, 15.84, 17.71, 19.60, 23.36, 28.05 and 31.87 MeV in the centre-of-mass system. The study of angular distributions is performed in a wide angular range. Our theoretical calculations explain the experimental results and follow breakup threshold anomaly phenomenon near the Coulomb barrier. We discuss the variation of reflection function |S l | with ‘l’ for each contributing partial wave and calculate reaction cross section for the system against the projectile energy 31.87 MeV with permissible error.

Absorption and scattering of a high dimensional non-commutative black hole

In this work, we investigate the scattering of massless plane scalar waves by the high dimensional non-commutative Schwarzschild–Tangherlini black hole. We use the partial wave approach to determine the scattering and absorption cross sections in the incident wavelength range. Our numerical results demonstrate that the bigger the non-commutative parameter, the smaller the maximum value of the related partial absorption cross section, however the tendency is slightly. We also discovered that when the non-commutative parameter is weak, the absorption cross section of the high dimensional black hole oscillates in the low frequency zone. The total absorption cross section oscillates around the geometrical optical limit in the high frequency range, and the scattering characteristics of black holes with various parameters are visibly different. The influence on the differential scattering cross section is particularly pronounced at large angles.

Study of Differential Scattering Cross-Section Using Yukawa Term of Medium-Modified Cornell Potential

In the present work, we have studied the differential scattering cross-section for ground states of charmonium and bottomonium in the frame work of the medium-modified form of quark-antiquark potential and Born approximation using the nonrelativistic quantum chromodynamics approach. To reach this end, quasiparticle (QP) Debye mass depending upon baryonic chemical potential ( μ b ) and temperature has been employed, and hence the variation of differential scattering cross-section with baryonic chemical potential and temperature at fixed value of the scattering angle ( θ = 9 0 o ) has been studied. The variation of differential scattering cross-section with scattering angle θ (in degree) at fixed temperature and baryonic chemical potential has also been studied. We have also studied the effect of impact parameter and transverse momentum on differential scattering cross-section at θ = 90 o .

Scattering analysis of two-dimensional Airy beams by typical non-spherical particles.

The scattering of structured light beams by various particles is an important subject of research with myriad practical applications, such as the manipulation, measurement, and diagnosis of small particles. We carry out an analysis of the scattering of two-dimensional (2D) Airy beams by typical non-spherical particles. The electric and magnetic field vectors of the incident Airy beams are derived by introducing a vector potential in the Lorenz gauge. The scattered fields of the particles are obtained by utilizing the method of moments based on surface integral equations. Some numerical simulations for the scattering of 2D Airy beams by several selected non-spherical particles are performed and analyzed. Especially, a spheroidal particle is taken as an example, and the effects of various parameters describing the 2D Airy beams on its differential scattering cross section are examined. It is expected that this work will be helpful for understanding the interactions of 2D Airy beams with non-spherical particles and their further applications.

Parametrized black holes: scattering investigation

We study the scattering of light-like geodesics and massless scalar waves by a static Konoplya–Zhidenko black hole, considering the case that the parametrized black hole solution contains a single deformation parameter. By performing a geodesic analysis, we compute the classical differential scattering cross section and probe the influence of the deformation parameter on null trajectories. Moreover, we investigate the propagation of a massless scalar field in the vicinity of the static Konoplya–Zhidenko black hole and use the plane waves formalism to compute the differential scattering cross section. We confront our numerical results in the backward direction with the glory approximation, finding excellent agreement. We compare the results for the deformed black hole with the Schwarzschild case, finding that the additional parameter has an important role in the behavior of the scattering process for moderate-to-high scattering angles.

Scalar scattering by black holes and wormholes

We study the scattering of monochromatic planar scalar waves in a geometry that interpolates between the Schwarzschild solution, regular black holes and traversable wormhole spacetimes. We employ the partial waves approach to compute the differential scattering cross section of the regular black hole, as well as of the wormhole solutions. We compare our full numerical results with the classical geodesic scattering and the glory approximation, obtaining excellent agreement in the appropriate regime of validity of such approximations. We obtain that the differential scattering cross section for the regular black hole case is similar to the Schwarzschild result. Notwithstanding, the results for wormholes can be very distinctive from the black hole ones. In particular, we show that the differential scattering cross section for wormholes considerably decreases at large scattering angles for resonant frequencies.

Effective interaction potentials and the scattering cross sections of the Lorentzian dense semiclassical plasma particles

Modified versions of the dynamic effective interaction potentials for the charged particles in dense semiclassical plasma are presented. These models consider dynamic screening, quantum mechanical effect of diffraction and particle velocity distribution function with non-Maxwellian suprathermal tail. Such distributions are well described by the so-called kappa-distribution and can be used in different space plasma and in some plasma installations where the suprathermal particles take place. Based on this modified dynamic interaction potentials the differential scattering cross sections of the electron-electron and electron-ion collisions were investigated. The obtained results for different values of the density parameter, coupling parameter and spectral index κ are presented.

Scattering properties of charged black holes in nonlinear and Maxwell’s electrodynamics

We investigate the scattering properties of a massless scalar field in the background of a charged Ay\'on-Beato-Garc\'ia regular black hole solution. Using a numerical approach, we compute the differential scattering cross section for arbitrary values of the scattering angle and of the incident wave frequency. We compare our results with those obtained via the classical geodesic scattering of massless particles, as well as with the semiclassical glory approximation, and show that they present an excellent agreement in the corresponding limits. We also show that Ay\'on-Beato-Garc\'ia and Reissner-Nordstr\"om black hole solutions present similar scattering properties, for low-to-moderate values of the black hole electric charge, for any value of the scattering angle.

A novel SAXS model for multi-texture systems: application to CaCO3 calcination using in-situ USAXS-SAXS-WAXS

SAXS models, used to calculate the micro-textural properties (porosity, specific surface, correlation length, correlation function) of porous materials, are especially relevant for in-situ material characterization. Certain classes of porous materials, including those generated during solid decompositions, are characterized by distinct regions with different micro-textures. Classical SAXS models cannot be applied directly to such multi-texture systems, thus a novel SAXS model for multi-texture systems is proposed in this work and validated by using measurements of micro-textural properties of a calcined CaCO3 powder, obtained using time-resolved in-situ synchrotron radiation USAXS, SAXS and WAXS data. The proposed model, in contrast to the direct application of classical SAXS models, is capable of correctly predicting the expected linear trend of the particle internal porosity with respect to the CaCO3 conversion and provides a complete description of the micro-textural properties, in very close agreement with experimental data available in the literature. In the reaction product region the correlation function, as well as the other micro-textural properties, is essentially constant during the solid decomposition, and is accurately represented by a two-parameter model. Based on the proposed SAXS model, a simplified expression of the differential scattering cross section, as a product of the CaO mass fraction times a time-independent function of the correlation function, is obtained; such expression can reliably predict the experimental scattering intensity profiles over time.