L. J. Kieffer

LOW-ENERGY ELECTRON-COLLISION CROSS-SECTION DATA. PART I. IONIZATION, DISSOCIATION, VIBRATIONAL EXCITATION.

Graphical displays of selected experimental data on cross sections as functions of electron energy are presented for some 60 targets important in aeronomy, astrophysics, and plasma physics. The processes covered are ionization, dissociation, and vibrational excitation. Criteria for data selection are discussed. The literature available up to September 1968 has been searched.

Compilation of atomic ultraviolet photoabsorption crosssections for wavelengths between 3000 and 10 Å

Graphical displays of selected experimental data on atomic photoabsorption crosssections as functions of wavelength are presented for 24 atoms. Criteria used in the data selection are discussed. References for all data chosen and an author index are included. The literature has been covered through October 1969.

Low-energy electron-collision cross-section data: Part III: Total scattering; differential elastic scattering*

A compilation is made of low energy electron-collision cross section data. Experimental values only are presented for all atomic species and for those molecules which are important for aeronomy, astrophysics, and plasma physics. The data included are taken from the literature published through July 1970. (JFP)

Electron energy dependence of the energy and angular distributions of O− from dissociative ion pair formation in O2

The energy and angular distributions of O− produced from O2 by dissociative ion pair formation have been measured at selected incident electron energies from threshold to 100 eV. The kinetic energy distributions show well‐defined maxima near 2.0 and 3.3 eV with appearance potentials, respectively, at 20.0 and 23.0 eV. The angular distributions are peaked in the forward and backward directions relative to electron beam and exhibit nondipolar structure. The shape of the distributions depends on electron energy, becoming more isotropic with increasing energy. An attempt has been made to explain the behavior of the angular distributions in terms of a superposition of final states using a multipole expansion of the differential cross section which includes the effects of higher‐order partial waves.

Electron energy dependence of the kinetic energy and angular distributions of O+ from dissociative ionization of O2

The electron energy dependence of the kinetic energy and angular distributions of O+ have been measured for the process of dissociative ionization of O2. The kinetic energy distributions for energies above 0.5 eV are compared with other dissociative ionization measurements as well as results of dissociative photoionization and dissociative excitation by electrons leading to production of Rydberg excited neutral fragments. Angular distributions are interpreted in terms of symmetries of possible molecular ion states contributing to dissociation, and the results near threshold are compared with recent measurements of O− from dissociative ion pair formation in O2. Information about the states of excitation of the dissociation fragments as a function of ion energy is obtained from appearance potential measurements. The results indicate that predissociation may be important and that dissociative ionization of O2 is in general a complicated process involving many O2+ states.

Angular distribution of N+ from dissociative ionization of N2 near threshold

Translational kinetic energy and angular distributions of N+ from dissociative ionization of N2 have been measured at electron energies close to threshold. For electron energies above 50 eV the energy distributions agree favorably with earlier measurements of Kieffer and Van Brunt. The ion energy distributions at electron energies below 50 eV are dominated by a feature peaked at a kinetic energy below 1 eV in agreement with recent measurements of Locht et al. For electron energies closest to threshold the angular distribution of N+ associated with this feature is consistent with the previously proposed mechanism involving excitation of the C 2Σ+u state followed by predissociation. At higher electron energies the degree of anisotropy increases and then rapidly decreases suggesting a significant contribution from direct excitation to the 4Σ+g repulsive state of N+2 leading to fragments in their ground states.

Low—Energy electron—Collision cross—Section data: Part II: Electronic—Excitation cross sections*

Presented here are graphical displays and tables of selected experimental data on cross sections for electronic excitation of some 20 atomic and molecular targets important in acronomy, astrophysics, and plasma physics. Values for both leveland line excitation are given as functions of energy of the impacting electron. Criteria for data selection are discussed. The literature available through December 1968 has been searched.

Bibliography of low energy electron collision cross section data

Abstract : A bibliography of low energy electron collision cross section data is presented. Only references which report original measurements or calculations of electron collision cross sections are included. The cross section data for each process are listed by atomic species in order of their atomic number. The data for molecules are listed in arbitrary order.