Theoretical investigation of scattering of an atomic projectile confined in a harmonic surface potential

In this paper, scattering of a projectile atomic gas confined in an atomic harmonic surface is studied using the Lippmann–Schwinger. The nonlocal separable potential of rank one has been assumed between the projectile gas and surface, because this potential is useful to investigate the few-body systems. The analytical solution of Lippmann–Schwinger equation has been derived, and the scattering properties including transition and scattering matrices, phase shift, scattering amplitude and time delay are calculated analytically as a function of incident atomic gas energies.     

Scattering state of the multiparameter potential with an improved approximation for the centrifugal term in D‐dimensions

Recently, multi‐parameter potential has been introduced and had been discussed as special cases of other potential model, that is why we are interested to the study of such a potential. In order to study this potential, the D‐dimensional Schrödinger has been presented in detail and the scattering state with any arbitrary J‐state due to this potential has been investigated approximately. After this step, we have discussed analytically the scattering and bound state for some special cases in D‐dimensional situations which play important roles in physics. © 2015 Wiley Periodicals, Inc.     

Overtone intensities in resonance Raman scattering

A model calculation of resonance Raman scattering tensors has been carried out for a diatomic molecule with a harmonic potential for the ground state and a linear repulsive potential for the excited state. Expressions for scattering tensors have been obtained by using a series of recurrence formulas induced from the Green function of the nuclear hamiltonian of the repulsive potential of the excited state and nuclear wavefunctions for the harmonic potential. The relative scattering intensities of overtones depend on the gradient of the repulsive potential curve and are interpreted in terms of the overlap integrals between nuclear wavefunctions of upper and lower states.     

Liquid drop and optical model calculations of elastic,vibrationally inelastic and absorptive scattering of4He atoms from4He n -clusters

The scattering of He atoms from liquid He _n -clusters withn=10 to 1000 at energies between 0.01 and 5.0 meV has been investigated by calculating integral cross sections for elastic scattering, absorption scattering and vibrational excitation of the liquid drop vibrations using a hard core potential, a transparent core potential, a black core and an optical model potential. The implications for planned scattering experiments are discussed.     

Field-theoretical approach to vibrational excitation in atom—diatom collinear collisions

The field-theoretical atom—diatom scattering equations of Csanak have been tested numerically, assuming a collinear collision model, with an exponential repulsive interaction potential and with a harmonic oscillator approximation for the molecule. Dyson's equation, in its integral form, has been solved obtaining orbitals representing the elastic scattering of an atom off the target and these Dyson's orbitals have been used to evaluate a matrix element containing a transition potential. This has been obtained by approximating Bethe—Salpeter's equation and yields directly the transition amplitudes for inelastic scattering. The results for single and multiple-jumps compare favourably with the exact values of Secrest and Johnson, and refinements of the model are suggested for further improvements.     

An endogenous multiple scattering method for the calculation of the elastic scattering cross sections of electron shape resonances in polyatomic molecu

A procedure is described for obtaining the scattering potential for elastic electron—molecule scattering within the one-electron overlapping sphere multiple scattering Xα method. The method has been used to calculate the total elastic electron scattering cross sections for the nitrogen, ethylene and 1,3,5-trifluorobenzene molecules, which compare well with experimental data.     

Effect of Interaction Potential on Laser-assisted e-Ar Scattering

The interaction potentials between electron and atom play an important role in electron-atom scattering. Using three potential models, the absolute differential cross section has been calculated by the second Born approximation theory. Results show that these model potentials are successful in the laser-assisted e-Ar scattering system. The influence of static potential, exchange potential and polarization potential on the absolute differential cross section is also analyzed and discussed.     

Total (elastic + inelastic) cross sections for electron scattering with bound and free germanium and lead atoms

Spherical complex optical potential (SCOP) approach has been used to compute the differential, total (elastic + inelastic) and momentum transfer cross sections for electrons scattering from the bound and free germanium and lead atoms in the energy range from 100–5000 eV. We find that the present calculated differential scattering cross sections (DCS) exhibit all important features (such as forward peaking, dip at middle angles and enhanced backward scattering) observed in other theoretical calculations and experimental measurements. The effect of absorption potential is generally to reduce the elastic cross section.     

Scattering Resonance States and Partial Potential Energy Surface of Reaction I+HI(v=0)→IH(v′=0)+I

The partial potential energy surface of the I HI→IH I reaction involving the translational and vibrational motions has been constructed at the QCISD(T)//MP4SDQ level with the pseudo potential method that is helpful to interpreting the scattering resonance states. The lifetimes of the scattering resonance states in the title reaction obtained from the partial potential energy surface are about 90-120 fs, which agrees with the result of high-resolved threshold photodetachment spectroscopy of anion IHI- measured by Neumark.     

Development of tip-enhanced optical spectroscopy for biological applications: a review

Tip-enhanced optical spectroscopy is an approach that holds a good deal of promise for the nanoscale characterisation of matter. Tip-enhanced Raman spectroscopy (TERS) has been demonstrated on a variety of samples: inorganic, organic and biological. Imaging using TERS has been shown for carbon nanotubes due to their high scattering efficiency. There are a number of compelling motivations to consider alternative approaches for biological samples; most importantly, the potential for heat damage of biomolecules and long acquisition times. These issues may be addressed through the development of tip-enhanced coherent anti-Stokes Raman scattering microscopy.     

Theory of the potential of a donor ion in silicon

In this paper a variational principle has been formulated for obtaining an approximate solution of Poisson's equation for the potential of a donor ion embedded in Si. A comparison of a two parameter approximate analytical potential with the exact numerical potential shows excellent agreement for several electron concentrations. It is also found that the present theory, using the concept of a “spatially variable dielectric constant,” leads to a donor-ion potential which deviates significantly from the potential of Dingle, which has been the traditional starting point of calculations of electron mobility limited by ionized-impurity scattering.     

Effect of displacement and distortion of potential energy surfaces and overlapping resonances of electronic transitions on surface-enhanced Raman scattering: models and ab initio theoretical calculation

A previously developed theory for the temperature-dependent resonance Raman scattering is used to study the surface-enhanced Raman scattering. Two models, the displaced oscillator model and the displaced-distorted oscillator model, based on the harmonic potential energy surfaces are carried out to calculate the surface-enhanced Raman scattering excitation profiles of the pyridine molecule adsorbed on a silver electrode, for which the density functional theory method is applied to evaluate the potential energy surfaces of the adsorption structure. In this framework, the distortion effect on the surface-enhanced Raman scattering will be discussed by comparing both models. The overlapping resonance of multiexcited electronic transitions is also studied, in which the interference between electronic transitions has been taken into account. It will be used to study the abnormal band at 1005.6 cm(-1) with the exciting radiation 457.9 nm.     

From fractal to nanorod porphyrin J-aggregates. Concentration-induced tuning of the aggregate size

A structural change from fractal to nanorod J-aggregates of tetrakis(4-sulfonatophenyl)porphyrin has been obtained by acting on the intermolecular interaction potential. The size and shape of these self-assembled porphyrin clusters have been monitored under different experimental conditions, by means of polarized and depolarized dynamic light scattering and small and wide angle elastic light scattering. At sufficiently low porphyrin concentration and high ionic strength, the shielded repulsive potential seems to be responsible for the fractal structure of the aggregates. On the contrary, at low ionic strength (nonshielded potential) and high porphyrin concentration, these species self-assemble in a rodlike arrangement. The length of the so-formed rod-shaped aggregates decreases on increasing porphyrin concentration. Moreover, both fractals and rods display a structure-dependent optical activity induced by a chiral template.     

A light scattering study of concentrated dispersions in nonaqueous media

Interparticle interactions between colloidal poly(methylmethacrylate) particles stabilised by poly(12-hydroxystearic acid) in non-aqueous media have been investigated using time-average light scattering. The problem of multiple scattering was avoided by using a binary mixture of solvents such that the colloidal particles were optically matched. This enabled the static structure factor to be measured and from the small scattering vector expansion the osmotic pressure to be determined. The softness of the pairwise interaction potential has been exposed using the Chandler-Weeks-Anderson perturbation theory. However, it is concluded that dispersions of the type studied can be reasonably well approximated by a hard sphere fluid model.     

Scattering Resonance States and Partial Potential Energy Surface of Reaction I ＋ HI （ v = 0 ） → IH （ v＇ = 0 ） ＋ I

The partial potential energy surface of the I ＋ HI →IH ＋ I reaction involving the translational and vibrational motions has been constructed at the QCISD（ T ）//MP4SDQ level with the pseudo potential method that is helpful to interpreting the scattering resonance states. The lifetimes of the scattering resonance states in the title reaction obtained from the partial potential energy surface are about 90-120 fs, which agrees with the result of high-resolved threshold photodetachment spectroscopy of anion IHI^- measured by Neumark.     

Protein-nanoparticle labelling probed by surface enhanced resonance Raman spectroscopy

A benzotriazole dye has been attached to a heme protein via a Michael addition and the unique potential of surface enhanced resonance Raman scattering (SERRS) to provide informative in situ recognition of more than one label on one protein demonstrated.     

The N2Ar potential energy surface

The potential energy surface for the N₂Ar system has been obtained assuming a spherical average interaction previously reported from this laboratory. The angular dependence has been assessed by a combined analysis of the integral and differential scattering cross sections and sonic spectroscope data. The potential energy surface is given via a parametric model. A similar potential energy surface for O₂Ar has been obtained with the same procedure. This surface is an improvement of an earlier one, because it reproduces the differential total cross sections recently measured.     

Collisional quenching at ultralow energies: controlling efficiency with internal state selection

Calculations have been carried out for the vibrational quenching of excited H(2) molecules which collide with Li(+) ions at ultralow energies. The dynamics has been treated exactly using the well-known quantum coupled-channel expansions over different initial vibrational levels. The overall interaction potential has been obtained from the calculations carried out earlier by our group using highly correlated ab initio methods. The results indicate that specific features of the scattering observables, e.g., the appearance of Ramsauer-Townsend minima in elastic channel cross sections and the marked increase of the cooling rates from specific initial states, can be linked to potential properties at vanishing energies (sign and size of scattering lengths) and to the presence of either virtual states or bound states. The suggestion is made such that by selecting the initial state preparation of the molecular partners, the ionic interactions would be amenable to controlling quenching efficiency at ultralow energies.     

Ab initio based tight-binding molecular dynamics simulation of the sticking and scattering of O2Pt(111)

The sticking and scattering of O(2)Pt(111) has been studied by tight-binding molecular dynamics simulations based on an ab initio potential energy surface. We focus, in particular, on the sticking probability as a function of the angle of incidence and the energy and angular distributions in scattering. Our simulations provide an explanation for the seemingly paradox experimental findings that adsorption experiments suggest that the O(2)Pt(111) interaction potential should be strongly corrugated while scattering experiments indicate a rather small corrugation. The potential energy surface is indeed strongly corrugated which leads to a pronounced dependence of the sticking probability on the angle of incidence. The scattered O(2) molecules, however, experience a rather flat surface due to the fact that they are predominantly scattered at the repulsive tail of the potential.