Angular distributions of photoelectrons ejected from uranium by 1.118 MeV gamma rays

At a gamma-ray energy of 1118 keV, we have studied longitudinal angular distributions of photoelectrons ejected from the K-, L-, and M+N+…-shells of uranium. The application of these angular functions to the calculation of the photoelectric correction factor ƒ is discussed. It is important to obtain ƒ at an energy such as 1.118 MeV to increase the accuracy, around 1 MeV, in the curve of ƒ versus energy. A smooth-curve relationship, in a log-log diagram, has been found between the gamma-ray energy hv and the angle θ_m of maximum photoelectric cross-section. It is pointed out that the Swedish computer BESK now undertakes calculations of ƒ at four gamma-ray energies: 412, 662, 1118 and 1332 keV (assuming rectangular symmetry and taking source size into account). This new calculation increases the accuracy of ƒ values such that the overall accuracy in ƒ between 400 and 1400 keV is now considered to be of the order of 1 %.     

Angular distribution of photoelectrons emitted from solids

The angular distributions of photoelectrons emitted from Cu, Ag and Au foils irradiated by Al Kα X-rays along the surface normal have been measured over a wide range of polar emission angles for different photoelectron lines. The experimental results are compared with analytical predictions based on a solution of the kinetic equation in the transport approximation, and satisfactory agreement is observed. The angular dependence of the photoelectron line intensity has been found to be less anisotropic than that of the differential photoelectric cross section. This effect is due to the elastic collisions that photoelectrons suffer on their way out of the target, and is more pronounced for samples with a high atomic number.     

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 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 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.     

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 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.     

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.     

Escape probability of O 1s photoelectrons leaving copper oxide

The escape probability of O 1s photoelectrons as a function of depth of origin in CuO has been studied experimentally and by the Monte Carlo technique. It has been proved experimentally that the escape probability in the direction of X-ray propagation is no longer described by a simple exponential law but is a complex function with a maximum at a depth of 4–10 Å. The mean escape depth is derived from the experimental data and is compared with the results of theory; satisfactory agreement is obtained.