Angular dependence of X-ray photoelectrons

The intensity of X-ray induced photoelectrons has been measured in function of the emission angle relative to the surface of solid samples. The angular     

Double atomic photoeffect in the relativistic domain: Angular and energy distributions of photoelectrons

We study the double ionization of the atomic K-shell by a single photon in the relativistic energy domain. The differential and total cross sections of the process are calculated. It is shown that the ratio of the cross sections of double and single ionization increases with the photon energy, tending to the limit 0.34/Z ², where Z is the atomic number or the nuclear charge. The formulas are found to be valid for Z≫1 and αZ≪1, where α=1/137 is the fine-structure constant. Zh. éksp. Teor. Fiz. 114, 1537–1554 (November 1998)     

Angular distributions of the fragments from coulomb explosions of diatomic molecules in intense laser fields

The angular distributions of the fragments from a Coulomb explosion of a diatomic heteronuclear molecule during multielectron dissociative ionization in a superintense field are considered in terms of classical mechanics. The patterns of angular distributions of the Coulomb explosion fragments are shown to differ in different ranges of laser pulse parameters. In particular, there are two distinct modes of fragment separation: separation in a Coulomb field and separation in the field of an effective “fragment + field” potential. The effective potential includes both the force of Coulomb repulsion between the fragments and the period-averaged force exerted on the system by the field; it can be determined by using the Kramers-Henneberger method. The limits of applicability of the Kramers-Henneberger method to the problem in question are discussed. These limits specify the range of field parameters in which the fragments fly apart in a direction perpendicular to the field for the initially arbitrary orientation of the molecular axis relative to the field.     

Angular distribution of photoelectrons from atomic oxygen at 736 Å and 584 Å

The angular distributions of photoelectrons ejected in the process $\text{O}\text{(2}\text{p}{}^4{}^3\text{P}\text{) + hv →}\text{O}{}^{\mathrm{+}}\text{(2}\text{p}{}^3{}^4\text{S}\text{) +}\text{e}$ and $\text{O}{}^{\mathrm{+}}\text{(2}\text{p}{}^3{}^2\text{D}\text{) +}\text{e}$ have been measured at the 736 Å NeI resonance line and at the 584 Å HeI resonance line. The results show good agreement with theory.     

Angular distribution of photoelectrons in the soft x-ray region

The angular distribution of photoelectrons ejected from the 2p shell in neon was investigated, for the first time, in the soft x-ray region, using a do     

Angular distributions of fast neutrons from the reaction

The angular distributions of neutrons from the reaction Co⁵⁹ (p, n) for 4 values of the proton energyE _p=5.23–4.05 MeV have been measured. The preliminary analysis of the results shows that in the reaction mechanism a certain role is played also by a direct process, most probably of a knock-out type, the relative contribution to the reaction yield of which decreases with decreasing value ofE _p.The authors would like to thank Prof. V. Petrílka for his constant interest in the work, the staff of the Cyclotron Laboratory of the Nuclear Research Institute of the Czechoslovak Academy of Sciences for their cooperation and the group of physicists of the Nuclear Reactions Department of the institute for lending most of the apparatus.     

Angular distributions of electrons photoemitted from chemisorbed atoms

A theory which describes the angular distributions of electrons photo-emitted from chemisorbed atoms is presented. Due to hole delocalization and preferential orientation, interference effects due to emission from various centers in a molecule do not average out, as they do in gas phase photoionization and much more structural information pertaining to chemisorption bonds is contained in such measurements.     

Angular distribution of low energy photoelectrons with defined spin orientation

On the basis of symmetry arguments general expressions are derived for the angular distribution of photoelectrons in defined spin states from atoms or molecules for the two cases of circularly and linearly polarized light. It is prooved that linearly polarized light or unpolarized light ionizing an isotropic ensemble of atoms or molecules will allways produce unpolarized electrons in all directions in the electric dipole approximation.     

Multiphoton electron angular distributions from laser-aligned CS2 molecules

Laser-aligned carbondisulfide (CS2) molecules are singly ionized by multiphoton absorption from intense, linearly polarized 25 fs laser pulses. The angular distribution of the photoelectrons exhibits a significant dependence on the angle between the polarizations of the aligning and ionizing laser fields. The widely used strong-field approximation predicts angular distributions in qualitative agreement with the experimental data but fails at a quantitative level.     

Angular distribution of photoelectrons after photoionization by elliptically polarized light

The angular distribution of photoelectrons after photoionization by elliptically polarized light is derived.     

Angular distribution of photoelectrons at 584 Å using polarized radiation

Photoelectron angular distributions for Ar, Xe, N₂, O₂, CO, CO₂, and NH₃ have been obtained at 584 Å by observing the photoelectrons at a fixed angle and simply rotating the plane of polarization of a highly polarized photon source. The radiation from a helium DC glow discharge source was polarized (84%) using a reflection type polarizer.     

Energy and angular distributions of photoelectrons in multiphoton ionization

The energy and angular distributions of photoelectrons in the photoionization of an atom or ion by powerful laser radiation are calculated. The results obtained are valid for all values of the Keldysh parameter γ. Linear and circular polarizations of the light are considered. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 8, 493–497 (25 October 1999)     

Angular distributions of penning electrons

Angular distributions of electrons ejected in thermal collisions of He(2¹ S, 2³ S)-metastables with Ar, Kr, Xe, Hg, CO, N₂ are measured with respect to the vector of relative velocity of the colliding particles. Except for preliminary results on the He(2₁S, 2³ S)-/Ar-system, these are the first such distributions reported. They are found to be strongly anisotropic and asymmetric in some cases, and approximately isotropic in those cases where the interaction potential between the metastable- and the target particle is strong. For the cases of weak interaction potential, the connection between the “internal” angular distribution in the frame fixed to the internuclear axis and the laboratory angular distribution, has been derived. Calculations of laboratory angular distributions involving an assumed “internal” distribution and the kinematics of a hard core collision show good qualitative agreement with the experimental results.     

Angular distributions of atoms sputtered from polycrystalline FCC- and BCC-metals

When polycrystalline target materials are sputtered with high energy Ar⁺-ions at oblique ion incidence, the anisotropy of the low energy flux beneath the target surface can be estimated from the asymmetry of the angular distribution. As too it is predicted from random cascade theory, the measured emission profiles are almost symmetrical to the target normal indicating an isotropical flux of recoils inside the target. Nevertheless even symmetrical emission profiles show characteristic deviations from the cosine law. They have to be related to the low energy cascade, which strongly depends on lattice structure and surface binding. Born-Mayer repulsion, a surface atom suffers from its next neighbours when it is ejected, is proposed to generate these differences among the specific emission profiles.