Electronic excitations of CH2 2
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An atom trapping technique for determining absolute, total ionization cross sections (TICS) out of an excited atom is presented. The unique feature of our method is in utilizing Doppler cooling of neutral atoms to determine ionization cross sections. This fluorescence-monitoring experiment, which is a variant of the ``trap loss'' technique, has enabled us to obtain the experimental electron impact ionization cross sections out of the Cs $6\phantom{\rule{0.2em}{0ex}}^{2}{P}_{3∕2}$ state between $7\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ and $400\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. CCC, RMPS, and Born theoretical results are also presented for both the ground and excited states of cesium and rubidium. In the low energy region $(<11\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ where best agreement between these excited state measurements and theory might be expected, a discrepancy of approximately a factor of five is observed. Above this energy there are significant contributions to the TICS from both autoionization and multiple ionization.
Autoionization
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The structure of the atom is analyzed using the results of established experiments on ionization energies and spectral emissions. Ionization energy levels - when electrons are energized to escape from the Potential Energy Well of the atom – show distinct patterns. The depth of the Potential Energy Well is directly proportional to the number of protons in the nucleus, but is not dependent on the number of neutrons. The ionization energies, and therefore the electron depths, are similar to those of a multi-layered ball of electrons, as if they simply fill the three-dimensional Potential Energy Well around the nucleus. The electrons appear to be loosely-packed for the lighter elements, and more tightly-packed for the heavier elements. The electrons appear to be much larger than we presently imagine.
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We investigate the spin-polarized electron impact ionization of laser-excited alkali atoms. The triply differential cross section is decomposed into orientation and alignment parameters which can be directly measured. This paper extends a theoretical frame recently developed for unpolarized electrons.
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The emission of low-energy electrons from H2O has been investigated at photon excitation energies in the vicinity of the O 1s ionization threshold. Neutral oxygen Rydberg atoms (O*) were found to form, and the correlation between the initial inner-shell excited state of H2O and the Rydberg state of O* was determined. The initially excited electron in a Rydberg orbital is shown to remain associated with O* even after the cleavage of two O-H bonds. We also show that the energy discrepancy between two Rydberg states of H2O and O* can be explained by the influence of the post-collision interaction, which becomes stronger as the excitation energy approaches the 1s ionization threshold.
Rydberg atom
Rydberg matter
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Summary form only given, as follows. We report calculations of the chemi-ionization for the collisions of Mercury (Hg) atoms in the excited singlet and triplet P states (/sup 1,3/P), examining both the Penning and associative ionization mechanisms. The doubly-excited mercury dimer presents an intricate situation for chemi-ionization. For example, with only one of the atoms excited, chemi-ionization is not energetically possible. Some of the asymptotes correlating to two excited /sup 3/P atoms still lie just below the energy of the atomic ion so that only associative ionization can occur. On the other hand, others lie just above it, enabling both associative and Penning ionization. Potential energy curves for the excited neutral (Hg/sub 2/**) and the ion (Hg/sub 2//sup +/) molecular states are generated using relativistic effective core potentials and full four-electron configuration interaction, based upon the orbitals of the ground state at each internuclear distance. We have examined the influence of core-valence correlation and the errors associated with the interaction curves will be discussed. For such heavy atomic systems, the spin-orbit interaction plays an important role, and its inclusion follows from an effective hamiltonian based on the atomic splittings. Finally, we shall present the cross sections for Penning and associative ionization.
Penning ionization
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We have studied the electric field ionization of excited states of K and have found that it is similar in its gross features to the field ionization of Na. However, there are clear differences which are particularly important for applications. We attribute the differences to the coupling of states of different $|{m}_{l}|$ in high electric fields by the spin-orbit interaction of the K $p$ states.
Field desorption
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Summary form only given, as follows. We report calculations of the chemi-ionization for the collisions of Mercury (Hg) atoms in the excited singlet and triplet P states (/sup 1,3/P), examining both the Penning and associative ionization mechanisms. The doubly-excited mercury dimer presents an intricate situation for chemi-ionization. For example, with only one of the atoms excited, chemi-ionization is not energetically possible. Some of the asymptotes correlating to two excited /sup 3/P atoms still lie just below the energy of the atomic ion so that only associative ionization can occur. On the other hand, others lie just above it, enabling both associative and Penning ionization. Potential energy curves for the excited neutral (Hg/sub 2/**) and the ion (Hg/sub 2//sup +/) molecular states are generated using relativistic effective core potentials and full four-electron configuration interaction, based upon the orbitals of the ground state at each internuclear distance. We have examined the influence of core-valence correlation and the errors associated with the interaction curves will be discussed. For such heavy atomic systems, the spin-orbit interaction plays an important role, and its inclusion follows from an effective hamiltonian based on the atomic splittings. Finally, we shall present the cross sections for Penning and associative ionization.
Penning ionization
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