Photodetachment of 2p shell of the chlorine negative ion (original) (raw)
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Canadian Journal of Physics, 2009
The photodetachment cross sections and angular distribution asymmetry parameters are calculated for intermediate p shells of chlorine and bromine negative ions in the relativistic random phase approximation (RRPA) to account for relativistic effects and many electron correlations, and, additionally, in the modified RRPA (RRPA-R) to account for the relaxation of the atomic core in the photodetachment process. The results of the calculations with and without the relaxation effects are compared, and it is found that the results for cross sections with and without relaxation effects in RRPA-R and RRPA are very different close to the corresponding thresholds. An attempt is made to explain the difference between the results of RRPA and RRPA-R close to the corresponding channel thresholds.PACS Nos.: 32.80.Gc, 32.80.Fb
The Journal of Chemical Physics, 2000
Molecular chlorine was photolyzed using circularly polarized radiation at 310 and 330 nm, and orientation moments of the chlorine-atom Cl( 2 P j ) photofragment distributions were measured by resonance enhanced multiphoton ionization using circularly polarized light with Doppler resolution. The product atoms were found to be strongly oriented in the laboratory as a result of both incoherent and coherent dissociation mechanisms, and the orientation moments contributed by each of these mechanisms have been separately measured. The experimental results can be explained by nonadiabatic transitions from the C 1 ⌸ 1u state to higher states of ⍀ϭ1 u symmetry, induced by radial derivative coupling. Ab initio calculations indicate strong Rosen-Zener-Demkov noncrossing-type radial derivative couplings between states of 1 u symmetry. The observed angular distribution ͑ parameter͒ indicates that 88% of Cl*( 2 P 1/2 ) fragments produced at 310 nm originate from a perpendicular transition to the C state. The orientation measurements suggest that 67Ϯ16% of 35 Cl*( 2 P 1/2 ) atoms dissociate via the 1 u ( 3 ⌺ 1u ϩ ) state, and 21Ϯ6% dissociate via the 1 u ( 3 ⌬ 1u ) state.
ARTICLE pubs.acs.org/JPCA Dynamics of Cl (2Pj) Atom Formation in the Photodissociation of
2011
ABSTRACT: The photodissociation dynamics of fumaryl chloride (ClCO—CHdCH—COCl) has been studied in a supersonic molecular beam around 235 nm using resonance enhanced multiphoton ionization (REMPI) time-of-flight (TOF) technique by detecting the nascent state of the primary chlorine atom. A single laser has been used for excitation of fumaryl chloride and the REMPI detection of chlorine atoms in their spin-orbit states, Cl (2P3/2) and Cl * ( 2P1/2). We have determined the transla-tional energy distribution, the recoil anisotropy parameter, β, and the spin-orbit branching ratio for chlorine atom elimination channels. To obtain these, measured polarization-dependent and state-specific TOF profiles are converted into kinetic energy distributions, using a least-squares fitting method, taking into account the fragment recoil anisotropies, βi. The TOF profiles for both Cl and Cl * are found to be independent of laser polarization; i.e., β is well characterized by a value of 0.0, within the...
Atoms
Approximation methods are unavoidable in solving a many-electron problem. One of the most successful approximations is the random-phase approximation (RPA). Miron Amusia showed that it can be used successfully to describe atomic photoionization processes of many-electron atomic systems. In this article, the historical reasons behind the term “random-phase approximation” are revisited. A brief introduction to the relativistic RPA (RRPA) developed by Walter Johnson and colleagues is provided and some of its illustrative applications are presented.
Correlated processes in inner-shell photodetachment of the Na - ion
Journal of Physics B: Atomic, Molecular and Optical Physics, 2001
Photodetachment studies of negative ions have, until recently, involved the valence electrons only. Double excitation, a clear sign of the importance of electron correlation, has been investigated extensively during the past few decades[1]. Such measurements used lasers as the source of UV photons. At much higher levels of excitation, one can expect to observe thresholds and resonances in the photodetachment cross section arising from the detachment and/or excitation of an inner-shell electron. To reach these high levels of excitation, which in the present case lie in the XUV region, it is necessary to replace lasers with a synchrotron radiation source. The present experiment was performed on the photon-ion endstation 10.0.1.2 at the 10.0.1 beamline at the Advanced Light Source.
A complete quantum mechanical study of chlorine photodissociation
The Journal of Chemical Physics, 2012
A fully quantum mechanical dynamical calculation on the photodissociation of molecular chlorine is presented. The magnitudes and phases of all the relevant photofragment T-matrices have been calculated, making this study the computational equivalent of a "complete experiment," where all the possible parameters defining an experiment have been determined. The results are used to simulate cross-sections and angular momentum polarization information which may be compared with experimental data. The calculations rigorously confirm the currently accepted mechanism for the UV photodissociation of Cl 2 , in which the majority of the products exit on the C 1 1u state, with non-adiabatic couplings to the A 3 1u and several other = 1 states, and a small contribution from the B 3 0 + u state present at longer wavelengths.
Valence-shell photoionization of the chlorinelike Ca3+ ion
Absolute photoionization measurements were performed for a mixture of 2Po 3/2 ground-state and 2Po 1/2 metastable-state Ca3+ ions over the photon energy range 65.7–104.6 eV by merging an ion beam with a beam of monochromatized synchrotron radiation. The ionization threshold energy of the 2Po 3/2 ground state was measured to be 67.063 ± 0.015 eV, which is 0.207 eV lower than the value tabulated in the NIST database. Most of the observed resonances associated with multiple Rydberg series of autoionizing states have been assigned spectroscopically using the quantum defect form of the Rydberg formula, guided by relativistic Hartree-Fock calculations of resonance energies and oscillator strengths. Intermediate coupling R-matrix calculations performed using the semi-relativistic Breit-Pauli approximation are in suitable agreement with measured absolute photoionization cross section in the energy range studied for this complex Cl-like ion species.
Double photodetachment from the Cl^{-} ion
2004
Loosely bound systems such as negative ions are particularly well suited to explore the effects of electron correlation on atomic structure and dynamics. The structure of a negative ion differs intrinsically from that of an atom or positive ion due to the nature of the force binding the outermost electron. In an atom or positive ion the valence electron moves asymptotically in the long-range Coulomb field of a positively charged core consisting of the nucleus shielded by the other electrons.
Theoretical study of inner-shell photoionization cross sections and angular distributions
Journal of the American Chemical Society, 1974
Atomic photoionization cross sections and asymmetry parameters are calculated using a simple oneelectron model potential consisting of the positive nuclear charge at the origin surrounded by a series of negatively charged spherical shells. The radial Schrodinger equation is solved exactly for unbound states of the potential using Whittaker functions. Parameters for the model potential (shell radii and charges) are fitted using SCF charge densities. Applications are made to inner-shell ionizations of atoms and molecules as observed in ESCA (Mg K a and A1 K a photon energies), with emphasis on 1s ionizations for boron through neon and 2s and 2p ionizations for aluminum through argon. The periodic variation in cross section for ionization of a given orbital is discussed in terms of the photoelectron kinetic energy. Effects due to core relaxation are considered for the neon atom. The calculations are compared with experimental X-ray absorption coefficients and photoelectron spectral intensities. hotoelectron spectroscopy using soft X-ray sources P has recently become a widely used experimental technique for studying atoms, molecules, and solids. The basic experiment consists of bombarding a sample to be studied with nearly monoenergetic photons and measuring the properties of the ejected photoelectrons. Although most of the emphasis has centered around the energetics of the photoionization process leading to a determination of electron binding energies, with recent advances in the experimental technique it has become feasible to determine the intensity3 of photoelectron peaks as well as the angular (spatial) distri-bution4l5 of the ejected photoelectrons. With these additional parameters the experimentalist can begin to unravel more complex photoelectron spectra.6 The in-(I) (a) K.
Valence-shell photoionization of chlorinelike Ar^{+} ions
2011
Photoionization (PI) of ions is a fundamental process of importance in many high-temperature plasma environments, such as those occurring in stars and nebulae [1] and in inertial-confinement fusion experiments [2]. Quantitative measurements of photoionization cross sections for ions provide precision data on ionic structure and guidance to the development of theoretical models of multielectron interactions.