Electronic excitation in symmetric ion–atom collisions: Kr+ + Kr

1980 ◽  
Vol 58 (10) ◽  
pp. 1518-1523 ◽  
Author(s):  
E. Grant Jones
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Electronic Excitation ◽  
Potential Energy Curve ◽  
Energy Curve ◽  
Translational Energy ◽  
Collisional Excitation ◽  
Short Range Interaction ◽  
Range Interaction ◽  
Curve Crossing

Cross sections are reported for reactions of Kr+ with Kr at collision energies below 50 eV (cm) to excite the KrI resonance radiation from the 5s[3/2]10 and 5s′[1/2]10 levels. Reaction occurs by the transfer of translational energy into internal energy and each reaction is characterized by a kinetic energy threshold. Significant effects on the cross section are observed arising from variation of the J-state of the reacting Kr+ beam. The reactions are interpreted as collisional excitation occurring by means of a potential energy curve crossing in the short-range interaction region.

scholarly journals Short-Range Interaction Impact on Two-Dimensional Dipolar Scattering

2018 ◽  
Vol 173 ◽  
pp. 06008 ◽  
Author(s):  
Eugene A. Koval ◽  
Oksana A. Koval
Keyword(s):  
Cross Section ◽  
Short Range ◽  
Strong Dependence ◽  
Dipolar Interaction ◽  
Two Dimensional ◽  
Short Range Interaction ◽  
Range Interaction ◽  
Interaction Radius ◽  
Ultracold Polar Molecules ◽  
Spatial Dimensions

We report numerical investigation of the short range interaction influence on the two-dimensional quantum scattering of two dipoles. The model simulates two ultracold polar molecules collisions in two spatial dimensions. The used algorithm allows us to quantitatively analyse the scattering of two polarized dipoles with account for strongly anisotropic nature of dipolar interaction. The strong dependence of the scattering total cross section on the short range interaction radius was discovered for threshold collision energies. We also discuss differences of calculated scattering cross section dependencies for different polarisation axis tilt angles.

Photo-induced Dissociation and Optical Cross Section of Si-H and S-H Complexes in GaAs and AlGaAs

2002 ◽  
Vol 719 ◽  
Author(s):  
M. Barbé ◽  
F. Bailly ◽  
J. Chevallier ◽  
S. Silvestre ◽  
D. Loridant-Bernard ◽  
...  
Keyword(s):  
Carrier Concentration ◽  
Cross Section ◽  
Cross Sections ◽  
Electronic Excitation ◽  
Surface States ◽  
Antibonding State ◽  
Free Carriers ◽  
Bonding State ◽  
Uv Illumination ◽  
Optical Cross Section

AbstractIn GaAs, (Si,H) complexes are efficiently dissociated at 300 K by photons with energies above 3.5 eV. Their optical cross-section is 10-19-10-18 cm2. This dissociation is the result of an electronic excitation of the Si-H bond of the complex from a bonding state to an antibonding state. (Si,H) and (S,H) complexes in AlGaAs alloys are also dissociated under UV illumination with optical cross-sections similar to GaAs. In passivated 2D AlGaAs-GaAs heterostructures, the evolution of the extra sheet carrier concentration at low photon densities presents a loss of free carriers attributed to the filling of surface states. In AlGaAs and in 2D AlGaAs-GaAs heterostructures, the replacement of hydrogen by deuterium in the complexes shows that the (Si,D) and (S,D) complexes are significantly more stable than the (Si,H) and (S,H) complexes as previously found in GaAs:Si,H.

scholarly journals Dissoziation von H2+ und H3+ beim Stoß an Kr im Energiebereich 6 – 60 keV / Dissociation of H2+ and H3+ by Collision with Kr in the Energy Range between 6 to 60 keV

1976 ◽  
Vol 31 (11) ◽  
pp. 1303-1307 ◽  
Author(s):  
B. Lehmann
Keyword(s):  
Radio Frequency ◽  
Energy Range ◽  
Cross Section ◽  
Charge Exchange ◽  
Cross Sections ◽  
Ion Source ◽  
Energy Curve ◽  
Gas Target ◽  
The Cross

Abstract H2+ and H3+ ions, produced in a H2 plasma of a radio-frequency ion source, were accelerated to 6-60 keV and directed into a gas target of Krypton. The cross sections for the formation of H+ and H- resp. H2+, H+ and H- have been measured. In the case of H+, obtained from the dissociation of H2+, 2 maxima have been found in the present energy range. A third is known to be at about 100 keV. We discuss the applicability of the Massey' adiabatic hypothesis, known from the analysis of charge-exchange experiments, to the maxima in the cross-section vs. energy curve for dissociation experiments.

EVIDENCE FOR LONG-LIVED PROTON DECAY NOT FAR FROM THE β-STABILITY VALLEY PRODUCED BY THE 16O + 197Au REACTION AT 80 MeV

1996 ◽  
Vol 11 (12) ◽  
pp. 949-956 ◽  
Author(s):  
A. MARINOV ◽  
S. GELBERG ◽  
D. KOLB
Keyword(s):  
Potential Energy ◽  
Cross Section ◽  
Isomeric State ◽  
Production Cross Section ◽  
Potential Energy Curve ◽  
Production Cross ◽  
High Energy ◽  
Proton Decay ◽  
Energy Curve ◽  
Bombarding Energy

The reaction 16 O + 197 Au has been studied at a bombarding energy of 80 MeV. Long-lived proton decays with half-lives of about [Formula: see text] h and [Formula: see text] h, proton energies of several MeV and production cross-section in the nb region have been observed. The existence of long-lived high energy isomeric state(s) which decay by protons, directly or by delayed protons, is evident from the data. The possible connection with the second minimum in the potential energy curve is discussed.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

A technique for preparing semiconductor cross sections for both TEM and SEM analysis

1989 ◽  
Vol 47 ◽  
pp. 712-713
Author(s):  
Stanley J. Klepeis ◽  
J.P. Benedict ◽  
R.M Anderson
Keyword(s):  
Sample Preparation ◽  
Cross Section ◽  
Cross Sections ◽  
Sem Analysis ◽  
Preparation Technique ◽  
Ion Milling ◽  
Tem Analysis ◽  
Polished Cross Section ◽  
Area Of Interest ◽  
Polished Side

The ability to prepare a cross-section of a specific semiconductor structure for both SEM and TEM analysis is vital in characterizing the smaller, more complex devices that are now being designed and manufactured. In the past, a unique sample was prepared for either SEM or TEM analysis of a structure. In choosing to do SEM, valuable and unique information was lost to TEM analysis. An alternative, the SEM examination of thinned TEM samples, was frequently made difficult by topographical artifacts introduced by mechanical polishing and lengthy ion-milling. Thus, the need to produce a TEM sample from a unique,cross-sectioned SEM sample has produced this sample preparation technique.The technique is divided into an SEM and a TEM sample preparation phase. The first four steps in the SEM phase: bulk reduction, cleaning, gluing and trimming produces a reinforced sample with the area of interest in the center of the sample. This sample is then mounted on a special SEM stud. The stud is inserted into an L-shaped holder and this holder is attached to the Klepeis polisher (see figs. 1 and 2). An SEM cross-section of the sample is then prepared by mechanically polishing the sample to the area of interest using the Klepeis polisher. The polished cross-section is cleaned and the SEM stud with the attached sample, is removed from the L-shaped holder. The stud is then inserted into the ion-miller and the sample is briefly milled (less than 2 minutes) on the polished side. The sample on the stud may then be carbon coated and placed in the SEM for analysis.

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