Depolarised Rayleigh scattering from liquid carbon monoxide,nitrogen and oxygen

The spectral distributions and scattering cross sections of depolarised Rayleigh scattering have been determined for liquid carbon monoxide, nitrogen and oxygen at 77 K and atmospheric pressure. It is shown that the scattering arises predominantly from molecular orientational fluctuations. The experimental scattering cross sections at 488 nm are 7 ± 1 for CO, 16 ± 1 for N₂ and 46 ± 4 for O₂ in units of 10^?30 cm² sr^?1 molecule^?1, based on a recently determined value for the absolute depolarised scattering intensity for liquid argon. The estimated proportions of induced anisotropy scattering are 10% for CO, 2.5% for N₂ and 0.8% for O₂. It is shown that there is appreciable free rotation of N₂ and CO in the liquids at this temperature but for O₂ this motion is dissipated much more efficiently by molecular interactions.     

Studies on Nuclear Resonant Scattering of Synchrotron Radiation by 40K

The studies on nuclear resonant scattering by ⁴⁰K using synchrotron radiation are reviewed. Brilliant and high pure synchrotron radiation permitted us to observe the nuclear resonant forward scattering by ⁴⁰K in a powdered KCl sample, the excitation of which is impossible with ordinary radioactive sources. Furthermore, nuclear resonant inelastic scattering of synchrotron radiation by ⁴⁰K in the KCl sample at room temperature has been measured using a high-resolution monochromator. Adding to these, from the excitation experiments of ⁴⁰K, the energy and lifetime of the first excited state of ⁴⁰K were confirmed. These measurements clearly show that the studies on the electronic states through hyperfine interactions and the dynamical properties of potassium atoms, which are very important in material science and biology, are possible. It should be noted that ⁴⁰K is the natural isotope of potassium and weakly radioactive. Our observation of forward and inelastic scattering of the radioactive nuclide ⁴⁰K will lead to further studies on other radioactive nuclides the resonant forward and inelastic scattering of which are not observed to date.     

A review of some recent applications of small-angle scattering in studies of polydisperse systems and porous materials

Recent progress in two fields of small-angle scattering is reviewed: (a) New procedures have been developed by Kotlarchyk and Chen and by Triolo, Griffith, and Compere for calculating the intensity of the small-angle scattering from polydisperse systems of interacting particles of different sizes. These techniques have significantly increased the quantitative information that can be obtained from the scattering data. (b) The pore boundaries in many porous solids have been found to be fractal surfaces. In a porous solid in which the pores have an average diameter ϵ and the pore boundary surfaces have a fractal dimension D, the scattered intensity for qϵ, >> 1 is proportional to q^−(6-D), where q = πλ⁻¹sin(θ/2), θ is the scattering angle, and λ is the wavelength. Some small-angle scattering studies of fractal porosity are outlined.     

Electrochemical determination of the absolute cross-section of giant Raman light scattering by silver-silver adatom complexes

The procedure of the determining of changes in the background intensity in the giant Raman light scattering spectra at silver surface in solutions of silver salts, under the action of current changes during galvanostatic silver electrodeposition near the silver electrode equilibrium potential, suggested by authors, is substantiated. Expressions for the calculations of the quantitative values of the absolute background cross-section of the giant Raman light scattering, which is caused by the interaction of the metal electron plasma with silver adatoms, are derived. The relationship between the silver adatom concentration and the back-ground intensity in the giant Raman light scattering spectra allows estimating the absolute cross-section of the background of the giant Raman scattering for the metal-adatom complexes (1.02 × 10⁻²⁷ cm²/adatom) from preliminary experiments in sulfate solutions.     

X-ray scattering for the determination of fat content in dairy products

The scattering of X-rays from biological samples has been shown to produce characteristic profiles, which depend on their molecular structure. The highly ordered fat molecules in an adipose tissue result in a relatively sharp scattering peak at 1.1 nm^?1 with a scattering profile, which is considerably different from the scattering profile of a water-rich tissue. The latter is characterized by a broad scattering peak at about 1.6 nm^?1. A biological sample consisting of a mixture of both adipose and a water-rich tissue is expected to show a scattering profile, which is directly linked to the relative contribution of each component and would reflect the percentage by volume of each component in the mixture. In this work, X-ray scattering profiles of a number of dairy products and water are measured. The values of two selected X-ray scattering characterization parameters (I₁/I₂% and areas A₁/A₂% of the scattering peaks at 1.1 and 1.6 nm^?1, respectively) are plotted against the fat content of each of the measured dairy samples. Results show a strong linear dependence of each of the X-ray scattering parameters and the fat content of the investigated dairy products. These results suggest a possible use of such technique as a new, simple and straight forward method for determination of fat content of dairy products that would join and support the currently available techniques.     

Depolarized light scattering from critical polymer blends

Depolarized light scattering of binary polymer blends in disordered state near the demixing critical point is considered both theoretically and experimentally. It is shown that the depolarized scattering in such systems is predominantly due to double scattering processes induced by composition fluctuations. For long enough polymer chains, this scattering is stronger than the contribution from intrinsic anisotropy fluctuations. The general equation for the static and dynamic double scattering function is obtained in terms of the system structure factor. The scattering functions are calculated both analytically and numerically (dynamic part) for polymer blends. We found that the depolarized intensity depends on the polymerization degree N and the relative distance from the critical point τ = 1 – χ*/χ (where χ is the Flory‐Huggins interaction parameter and χ* its critical value) as I_vh ∼︁ N²/τ², which is in good agreement with the experimental data. It is also shown that the dynamic scattering function is decaying non‐exponentially. We calculate the relaxation rate and the non‐exponentiality parameter as functions of the scattering angle and τ. These theoretical predictions are compared with experimental data for three chemically different blends.     

Analytical Application of Resonance Rayleigh Scattering,Frequency Doubling Scattering,and Second-Order Scattering Spectra for the Sodium Alginate-CTAB System

Three new methods for the determination of trace amounts of sodium alginate (SA) based on the reaction of SA with cetyltrimethylammonium bromide (CTAB) by resonance Rayleigh scattering (RRS), frequency doubling scattering (FDS), and second-order scattering (SOS) have been investigated. The SA can react with CTAB in a pH 10.0 Britton–Robinson buffer to form a new product, which can lead to a significant enhancement of RRS, FDS, and SOS intensities and appearance of new spectra. The maximum scattering wavelengths, λex/λem, appear at 351 nm/351 nm for RRS, 240 nm/480 nm for SOS, and 870 nm/435 nm for FDS, respectively. The increments of the scattering intensities (ΔI) are proportional to the concentration of SA in a certain range. The detection limits (3σ) for SA are 3.69 ng mL^?1 for the RRS method, 6.91 ng mL^?1 for the FDS method, and 7.45 ng mL^?1 for the SOS method under optimum conditions. The proposed methods were applied to the determination of SA in real samples with satisfactory results.     

Differential scattering cross sections for collisions of alkali ions and atoms. II. Electronic excitation via rotational coupling in LiK+ and NaK+

Relative differential cross sections, for both direct and charge exchange scattering have been obtained for the Li⁺ + K, Na⁺ + K and K⁺ + Na alkali ion—atom collisions, over the energy range 200–1200 eV and for scattering angles 0–6 mrad (in one case 0–15 mrad)- The experimental results are compared to semiclassical calculations, based upon recent potential energy curves. The charge exchange probabilities are calculated by solving the time dependent Schrödinger equation in a two-state approximation. In the Li⁺+ K experiment diffraction effects are observed, which can be compared to the Fraunhofer diffraction. of an annular diaphragm.     

Experimental determination of the absolute cross-section of giant Raman light scattering by metal-metal adatom complexes at silver electrode

Changes in the background intensities in giant Raman scattering spectra for silver surface in silver sulfate solutions, appeared at the varying of the silver galvanostatic deposition current near the silver electrode equilibrium potential, are measured. The connection between the silver adatom concentration and the intensity of the giant Raman scattering background allowed determining the absolute cross-section for the giant Raman scattering involving adatom-metal complexes: 1.02 × 10⁻²⁷ cm²/adatom in sulfate solutions.     

Spectroscopy of size-selected sodium clusters

The method of angular resolved elastic scattering has been used to achieve a size selection of neutral sodium clusters. After the scattering process the clusters are ionized by single photon ionization with various laser energies and detected by a time-of-flight mass spectrometer. The elastic scattering of Na₂ by Ne serves as a test for the experimental setup. Angular dependence of scattered sodium clusters ionized with 308 nm shows a significant amount of fragmentation of the neutral Na₆ to Na₉ clusters which are observed in the Na ₅ ⁺ and Na ₆ ⁺ ion channels.     

Application of backscattering spectrometry for composition and thickness determination of zirconium oxide layers on autoclaved zircaloy

Summary The determination of atomic composition and thickness of zirconium oxide layers on zirconium based alloys is of practical interest in nuclear industry. This paper describes the application of backscattering spectrometry for the non-destructive determination of composition and thickness of zirconium oxide layers on autoclaved zircaloy coupons. The spectrometry used here is the Rutherford backscattering spectrometry (RBS) with 2.5 MeV α-particles, 3.05 MeV ¹⁶O(α,α)¹⁶O resonance scattering and ¹⁶O(p,p)¹⁶O elastic scattering with 2.5 MeV proton beam. Proton backscattering is found to be the most suitable technique for the overall compositional analysis of the layers whereas 3.05 MeV ¹⁶O(α,α)¹⁶O resonance scattering, for depth profiling of oxygen. The former technique is simple and provides rapid measurements. The lower stopping cross sections of protons and enhanced scattering cross section for oxygen over a wide range of proton energy enable the analysis of oxide layers of larger thicknesses. The thicknesses of these layers determined by backscattering are in good agreement with cross-sectional micrographs taken by scanning electron microscope (SEM).     

Light scattering from coloured systems: an example of polyaniline dispersions

Static light scattering of highly diluted dispersions in 0.005 M H₂SO₄ was used to determine particle parameters of polyaniline dispersions stabilized with colloidal silica. The refractive index of polyaniline n = 1.8 and the refractive index increment (dn/dc) = 0.22 cm³g⁻¹ at λ = 532 nm were determined. The light scattering data are affected by the absorption of the green polyaniline and by a small amount of aggregates. The absorption has a negligible effect on the results. The influence of the aggregates was corrected by using the intensity‐weighed size distributions determined by dynamic light scattering at different angles and by the two‐component separation in static light scattering. Both procedures yield the same result.     

Determination of the chain conformation of polypropylene in the crystalline state by neutron scattering

Summary Wide and small angle neutron scattering from melt-crystallised isotactic polypropylene mixtures of deuterated and protonated molecules were measured in aQ range of 0.003 Å^–1 to 0,8 Å^–1. The scattering curves between 0.1 Å^–1 and 0.8 Å^–1 are very sensitive to the amount of folding of the chains within a lamella. Different annealing conditions which influence the degree of crystallinit between 0.39 and 0.67 and the long spacing between 125 Å and 245 Å had an insignificant influence on the scattering in this range. For various arrangements of crystalline sequences scattering functions were calculated. Best agreement with the experimental scattering curves was obtained for a mixture of single and double crystalline sequences of equal proportion. An adjacent reentry folding model for the molecular conformation is not consistent with the experimental data.The neutron scattering experiments have been performed at the Institute Laue-Langevin in Grenoble/France and at the Kernforschungsanlage Jülich/Germany.     

Does compressibility affect the results obtained by small angle neutron scattering?

Recently a few papers have been devoted to the scattering by polymer solutions and blends^(1,2) assuming that the systems under investigation are compressible, contrarily to what is usually done. This is motivated by the fact that if one uses the theory of incompressible mixtures in scattering experiments, one obtains values of the Flory⁽³⁾ χ parameter which are inconsistent with the values obtained by other techniques. In this paper we would like to show that, contrarily to what has been said, the effect of compressibility can be easily evaluated; it is very small and already corrected in the classical treatment of the data used in light or neutron scattering experiments.     

Classical differential cross sections and rotational energy transfer distributions for realistic ion—molecule potentials in the CPST limit

Classical differential cross sections, rotational energy transfer distributions at specified scattering angles and the first moments of the rotational energy transfer distributions are calculated for two ion—molecule systems: K⁺ ?CSCl and Li⁺ ?CO. The deflection angles and change in angular momentum are calculated using classical perturbation scattering theory (CPST). Monte Carlo techniques are then used to calculate the orientation averaged total differential cross sections and the rotational energy transfer distributions. Results are compared with experiment and agreement is found to be satisfactory. These two systems represent two extremes in anisotropy. For Li⁺ ?CO a strong classical rainbow peak is still seen in the differential cross section, while in the K⁺ ?CSCl system the rainbow is complete quenched. In the rotational energy transfer distributions of both systems, rotational rainbow peaks are clearly observed. The calculations also predict a leveling off of the first moment of the rotational energy transfer distribution at high angles, corresponding to the transition to repulsive scattering. On the basis of these results some comments are made on the nature of classical rainbow scattering for anisotropic systems.     

Micelle formation in sodium hexadecyl sulfate surfactant solutions studied by small-angle neutron scattering

Micelle formation in aqueous sodium hexadecyl sulfate solutions is studied by small-angle neutron scattering. Measurements are carried out at different concentrations (1.1, 2.2, 3.2, 5.4, 10.9 and 32.8 mM/dm³) and at different temperatures (40°, 50°, and 60°C). The monotonous evolution of interparticle correlation can be observed on the measured scattering patterns. At high concentrations (10.9 and 32.8 mM/dm³) scattering patterns are described by interacting ellipsoids, but at low concentrations by non-interacting ellipsoids. Computation of the distance distribution function proved the ellipsoidal shape at 10.9 and 32.8 mM/dm³, but showed an unexpectedly large particle dimension and elongation of the micelles at lower concentrations.     

Impulsive inelastic scattering of O+(4S) by isotopic hydrogen molecules

We present experimental evidence that at relative energies above 10 eV the non-reactive inelastic scattering of O⁺ by H₂, D₂, and HD arises from impulsive elastic scattering of 0⁺ by individual H or D atoms. The relation of this impulsive non-reactive scattering to the reactive scattering from these systems is briefly discussed.     

In-plane polarisation correlation study of the 31 D state of helium excited by 40 eV electrons

Electron-photon polarisation correlations measured in the scattering plane defined by the incident and scattered electron momenta are reported for 40 eV electron impact excitation of the 3¹ D state of helium and for electron scattering angles in the range 40°≦?≦120°. When combined with the results of our earlier polarisation analysis on radiation emitted perpendicular to the scattering plane, detailed information on the shape and dynamics of the exicted state is obtained. In the small angular range of overlap (40–60°) there is excellent agreement with a pervious experimental study. The behaviour of the linear polarisation of the radiation emitted in the scattering plane is well reproduced by a multichannel eikonal theory for ?≦80°. Otherwise theories totally fail to described the excitation process.     

Electrochemical pathway for the quantification of SERS enhancement factor

This communication presents a new pathway for the more precise quantification of surface-enhanced Raman scattering (SERS) enhancement factor via deducing resonance Raman scattering (RRS) effect from surface-enhanced resonance Raman scattering (SERRS). To achieve this, a self-assembled monolayer of 1,8,15,22-tetraaminophthalocyanatocobalt(II) (4α-Co^IITAPc) is formed on plasmon inactive glassy carbon (GC) and plasmon active GC/AuNP surface. The surfaces are subsequently used as common probes for electrochemical and Raman (RRS and SERRS) studies. The most crucial parameters required for the quantification of SERS substrate enhancement factor (SSEF) such as real surface area of GC/AuNPs substarte and the number of 4α-Co^IITAPc molecules contributing to RRS (on GC) and SERRS (on GC/AuNPs) are precisely estimated by cyclic voltammetry experiments. The present approach of SSEF quantification can be applied to varieties of surfaces by choosing an appropriate laser line and probe molecule for each surface.     

Interaction of polymyxin B with ds-DNA, and determination of DNA or polymyxin B via resonance Rayleigh scattering and resonance non-linear scattering spectra

Assays were developed for DNA or polymyxin B (PMB) based on enhanced resonance Rayleigh scattering (RRS) and resonance nonlinear scattering (including second order scattering and frequency doubling scattering) that result from the interaction of PMB with DNA. A minor-groove binding mechanism is suggested from the results obtained with RRS and from absorption and circular dichroism spectroscopy. The types of interaction and reasons of RRS enhancement are discussed. Linear relationships do exist over a wide range between the intensity of enhanced scattering and the concentrations of either DNA or PMB. When ctDNA is used as a probe to determine PMB, the detection limit (3σ) is 9.8 ng mL^?1. When PMB is used as a probe to determine DNA, the detection limit (3σ) is in the range from 3.8 to 9.0 ng mL^?1.