Neutral Carbon Atoms Research Articles

Carbon influx flow rate in an Ohmically heated plasma in the FM-1 spherator

The flow rate of neutral carbon atoms during the initial start-up phase of an Ohmically heated plasma in th e FM-1 spherator was determined from the spatially resolved measurements of the carbon line radiation and independent measurements of spatial distribution of plasma density and electron temperature. This was accomplished by comparing the measured carbon line intensity with a numerical solution of time-dependen t couple d differential rate equations for several carbon ionization states. The differential equations used in the present model correspond to a spatially homogeneous medium. However, th e effects of plasma inhomogeneity were taken into account by calculating the plasma emission at each location using the experimentally measured electron density and temperature (i.e. the measured radial distributions of density and temperature were folded into the numerical calculations). The empirical flow rate of carbon atoms into the discharge. Γflow(t),was found to be Γflow(t)≃ne(t)/τflow. where τflow was 30–100 ms depending upon discharge conditions

Autodetaching state ofC−and autoionizing states of C

An autodetaching state of ${\mathrm{C}}^{\ensuremath{-}}$ and several autoionizing states of the neutral carbon atom are excited using the collisional-excitation method. The autodetaching ${\mathrm{C}}^{\ensuremath{-}}$ state lies at 7.44 \ifmmode\pm\else\textpm\fi{} 0.07 eV above the neutral-carbon ground state and has a dominant configuration of $2p3s3p^{4}D$. The observed autoionizing states of carbon are assigned inner-shell-excited configurations of $2s2{p}^{2}(^{4}P, ^{2}D, ^{2}P)nl$.

Energy of CH Calculated by Many-Body Perturbation Theory

The many-body perturbation theory of Brueckner and Goldstone has been used to calculate the total nonrelativistic energy of the CH molecule. We have used a single-center expansion with a complete set of basis states appropriate to the neutral carbon atom. At the equilibrium internuclear separation we calculate the total energy for CH to be -38.482\ifmmode\pm\else\textpm\fi{}0.02 a. u. as compared with the experimental value -38.479 a. u. We have also calculated a full potential curve for the $^{2}\ensuremath{\Pi}$ ground state of CH accurate to second order in the perturbation expansion.

Incoherent-Scattering Function for Atomic Carbon

The incoherent-scattering function, or Compton scattering factor, has been calculated for the neutral carbon atom with a Hartree-Fock wave function and with configuration-interaction wave functions containing up to 40 terms. Values obtained with the correlated wave functions differ from the Hartree-Fock value by as much as 22%.

Dipole Polarizability of the Neutral Carbon Atom and the Dipole-Dipole Interaction between Carbon Atoms

Many-body perturbation theory is used to calculate the dipole polarizability ${\ensuremath{\alpha}}_{d}$ of the neutral carbon atom in its $^{3}P$ ground state. The result is 2.38 ${\mathrm{\AA{}}}^{3}$ in lowest order. When correlations are included by calculating higher-order terms in the perturbation expansion, we obtain the value 1.54 ${\mathrm{\AA{}}}^{3}$ for ${\ensuremath{\alpha}}_{d}$ averaged over ${M}_{L}$ values. A calculation of the coefficient of the ${R}^{\ensuremath{-}6}$ term in the van der Waals interaction between two carbon atoms each in the $^{3}P$ ground state is also reported.

Molecular two-centre integrals

The construction of the penetration operator, representing the potential of an electron in the field of a neutral carbon atom, is discussed. Formulae are given for all possible Coulomb-penetration ...

Relation between the Phase Shift and the Existence of Negative Ions

Studies on the behavior of the phase shift lambda near zero energy indicate the number of bound states m and whether the existence of negative ions is possible or not. Some numerical results for lambda /sub H/ and lambda /sub K/ for a neutral carbon atom are tabulated. (P.C.H.)

The bound free continuum for C −

The wave functions for the ground state of carbon and the negative carbon ion are determined using our small variation program. The Coulomb potential for the free electron is then computed using the carbon wave function thus obtained, and the subsequent obtention of the s- and d-wave portions of the free electron wave function is detailed. The dipole length form of the matrix elements is then determined for the various desired values of the free electron momenta under the assumption that the lower state is the complete negative carbon ion wave function while the upper state is the antisymmetric product made up of the free electron plus the complete neutral carbon atom wave functions. Finally a simple calculation using the matrix element results provides the photo-ionization cross section.

Electron spin densities in alternant hydrocarbon mononegative and mono-positive ions and in odd alternant hydrocarbon radicals

A comparison is made between MO calculations of electron spin densities in alternant hydrocarbon mono-negative and mono-positive ions and in odd alternant hydrocarbon radicals. For the positive and negative ions the Huckel MO treatment leads to satisfactory results, whereas for radicals configuration interaction must be taken into account. In a preliminary communication McConnell and Chesnut (see ref [14]) also noticed the necessity of π-π interaction in the MO calculations of electron spin densities of hydrocarbon free radicals. In this way negative spin densities are found for those carbon atoms in the radical at which in the non-bonding MO the electron densities are zero. This difference between alternant ions and radicals is due to the fact that in the singly charged ions the odd electron (‘positive hole’) may approximately be considered to move in the electrostatic field of the neutral carbon atoms of the hydrocarbon molecule, whereas in odd alternant hydrocarbon radicals the odd electron forms an in...

The chemistry of Glyoxaline, Pyrrole, and Pyrazole

The results of a study of glyoxaline, pyrrole, and pyrazole by the molecular-orbital method are reported. The theoretical data provide a detailed interpretation of the observed course of electrophilic substitutions in these heterocycles. Unequivocal predictions of the orientations for nucleophilic and radical substitutions in these compounds also emerge, but at present no relevant experimental information is available, with the exception of a possible case of radical substitution in glyoxaline. The present study also indicates that in conjugated systems, the electronegativity of a nitrogen atom carrying a formal negative charge (or a formal negative half-electronic charge) is appreciably less than that of a neutral carbon atom. This should assist in the assignment of electronegativity parameters in future molecular-orbital calculations.