scholarly journals Photoionisation of Unusual States of Matter: Atomic Ions, Excited States and Open-shell Atoms

1986 ◽  
Vol 39 (5) ◽  
pp. 799
Author(s):  
Steven T Manson ◽  
Samir K Bhattacharya
Keyword(s):  
Excited States ◽  
Periodic Table ◽  
Ground States ◽  
Closed Shell ◽  
Open Shell ◽  
Atomic Ions

Our understanding of the photoionisation of ground states of closed-shell atoms is fairly good. The situation is otherwise for open-shell atoms and for ions and excited states throughout the periodic table. Nevertheless, a number of interesting effects have been predicted theoretically in these unusual states of matter. In this paper, some of these predictions, not yet tested by experiment, shall be discussed, along with their implications.

scholarly journals Generalized Single Excitation Configuration Interaction: An Investigation into the Impact of the Inclusion of Non-Orthogonality on the Calculation of Core-Excited States

2019 ◽  
Author(s):  
Katherine J. Oosterbaan ◽  
Alec F. White ◽  
Diptarka Hait ◽  
Martin Head-Gordon
Keyword(s):  
Excited States ◽  
Configuration Interaction ◽  
Ground States ◽  
Closed Shell ◽  
Open Shell ◽  
Spatial Symmetry ◽  
Exchange Approximation ◽  
Novel Method ◽  
The Impact

<div>In this paper, we investigate different non-orthogonal generalizations of the configuration interaction with single substitutions (CIS) method for the calculation of core-excited states. Fully non-orthogonal CIS (NOCIS) has been described previously for singlets and doublets and this paper reports the extension to triplet molecules. In addition to NOCIS, we present a novel method, 1C-NOCIS(1C-NOCIS), for open-shell molecules which is intermediate between NOCIS and the static exchange approximation (STEX). We explore this hierarchy of spin-pure methods for singlet, doublet, and triplet molecules and conclude that, while NOCIS provides the best results and preserves the spatial symmetry of the wavefunction, 1C-NOCIS retains much of the accuracy of NOCIS at a dramatically reduced cost. For molecules with closed-shell ground states, STEX and 1C-NOCIS are identical.</div>

scholarly journals Generalized Single Excitation Configuration Interaction: An Investigation into the Impact of the Inclusion of Non-Orthogonality on the Calculation of Core-Excited States

2019 ◽  
Author(s):  
Katherine J. Oosterbaan ◽  
Alec F. White ◽  
Diptarka Hait ◽  
Martin Head-Gordon
Keyword(s):  
Excited States ◽  
Configuration Interaction ◽  
Ground States ◽  
Closed Shell ◽  
Open Shell ◽  
Spatial Symmetry ◽  
Exchange Approximation ◽  
Novel Method ◽  
The Impact

<div>In this paper, we investigate different non-orthogonal generalizations of the configuration interaction with single substitutions (CIS) method for the calculation of core-excited states. Fully non-orthogonal CIS (NOCIS) has been described previously for singlets and doublets and this paper reports the extension to triplet molecules. In addition to NOCIS, we present a novel method, 1C-NOCIS(1C-NOCIS), for open-shell molecules which is intermediate between NOCIS and the static exchange approximation (STEX). We explore this hierarchy of spin-pure methods for singlet, doublet, and triplet molecules and conclude that, while NOCIS provides the best results and preserves the spatial symmetry of the wavefunction, 1C-NOCIS retains much of the accuracy of NOCIS at a dramatically reduced cost. For molecules with closed-shell ground states, STEX and 1C-NOCIS are identical.</div>

Transalkylierung und protonenkatalysierte C-C-Spaltung bei n-Butyl-und n-Pentylbenzol in der Gasphase / Transalkylation and Proton Catalyzed C-C-Cleavage of Gaseous n-Butyl and w-Pentyl Benzenes

1979 ◽  
Vol 34 (3) ◽  
pp. 495-501 ◽  
Author(s):  
C. Wesdemiotis ◽  
H. Schwarz ◽  
C. C. Van de Sande ◽  
F. Van Gaever
Keyword(s):  
Hydrogen Exchange ◽  
Closed Shell ◽  
Open Shell ◽  
Molecular Ions ◽  
Exchange Reactions ◽  
Intramolecular Exchange ◽  
Carbon Carbon Bond ◽  
Exchange Processes ◽  
Reaction Channels ◽  
Alkyl Benzenes

Abstract The investigation of several 13carbon and deuterium labelled n-butyl and n-pentyl benzenes demonstrate that chemical ionization (reagent gas: methane) induces specific carbon-carbon bond cleavages of the alkyl group. The extent of competing reaction channels as for instance direct alkene elimination versus dealkylation/reprotonation is analyzed. Partial hydrogen exchange processes between reagent ions and substrate molecules are restricted to the phenyl ring. Intramolecular exchange reactions between the side chain and the aromatic ring which are typical for the open shell molecular ions of alkyl benzenes are not observed for analogous closed shell cations.

scholarly journals Exploring Cu/Al cluster growth and reactivity: from embryonic building blocks to intermetalloid, open-shell superatoms

2021 ◽  
Author(s):  
Max Schütz ◽  
Christian Gemel ◽  
Maximilian Muhr ◽  
Christian Jandl ◽  
Samia Kahlal ◽  
...  
Keyword(s):  
Closed Shell ◽  
Building Blocks ◽  
Open Shell ◽  
Cluster Growth ◽  
Powerful Technique

Cu/Al cluster growth reactions leading to open- and closed-shell superatoms are investigated. Therein, LIFDI-MS is presented as a powerful technique for the in situ detection of cluster identities and reactivity patterns.

Stresses and Deformations of Toroidal Shells of Elliptical Cross Section: With Applications to the Problems of Bending of Curved Tubes and of the Bourdon Gage

1952 ◽  
Vol 19 (1) ◽  
pp. 37-48
Author(s):  
R. A. Clark ◽  
T. I. Gilroy ◽  
E. Reissner
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Practical Interest ◽  
Closed Shell ◽  
Open Shell ◽  
Elliptical Cross Section ◽  
Axially Symmetric ◽  
Elliptical Cross ◽  
Two Parameters ◽  
Toroidal Shells

Abstract This paper is concerned with the application of the theory of thin shells to several problems for toroidal shells with elliptical cross section. These problems are as follows: (a) Closed shell subjected to uniform normal wall pressure. (b) Open shell subjected to end bending moments. (c) Combination of the results for the first and second problems in such a way as to obtain results for the stresses and deformations in Bourdon tubes. In all three problems the distribution of stresses is axially symmetric but only in the first problem are the displacements axially symmetric. The magnitude of stresses and deformations for given loads depends in all three problems on the magnitude of the two parameters bc/ah and b/c where b and c are the semiaxes of the elliptical section, a is the distance of the center of the section from the axis of revolution, and h is the thickness of the wall of the shell. For sufficiently small values of bc/ah trigonometric series solutions are obtained. For sufficiently large values of bc/ah asymptotic solutions are obtained. Numerical results are given for various quantities of practical interest as a function of bc/ah for the values 2, 1, 1/2, 1/4 of the semiaxes ratio b/c. It is suggested that the analysis be extended to still smaller values of b/c and to cross sections other than elliptical.

scholarly journals cAAC‐Stabilized 9,10‐diboraanthracenes—Acenes with Open‐Shell Singlet Biradical Ground States

2020 ◽  
Vol 59 (43) ◽  
pp. 19338-19343 ◽  
Author(s):  
Christian Saalfrank ◽  
Felipe Fantuzzi ◽  
Thomas Kupfer ◽  
Benedikt Ritschel ◽  
Kai Hammond ◽  
...  
Keyword(s):  
Ground States ◽  
Open Shell

Changes in Electronic Properties of Polymeric One-Dimensional {[M(CN)2]−}n(M = Au, Ag) Chains Due to Neighboring Closed-Shell Zn(II) or Open-Shell Cu(II) Ions

2011 ◽  
Vol 50 (1) ◽  
pp. 231-237 ◽  
Author(s):  
François Baril-Robert ◽  
Xiaobo Li ◽  
Michael J. Katz ◽  
Andrew R. Geisheimer ◽  
Daniel B. Leznoff ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Closed Shell ◽  
Open Shell ◽  
One Dimensional

scholarly journals Ligand-Mediated Spin State Changes in a Cobalt-Dipyrrin-Bisphenol Complex

2020 ◽  
Author(s):  
Nicolaas P. van Leest ◽  
Wowa Stroek ◽  
Maxime A. Siegler ◽  
Jarl Ivar van der Vlugt ◽  
Bas de Bruin
Keyword(s):  
Cobalt Complex ◽  
Closed Shell ◽  
Open Shell ◽  
Triplet Ground State ◽  
Redox Active Ligand ◽  
Redox Active ◽  
Square Planar ◽  
Amine Adducts ◽  
Meso Position ◽  
Electronic Ground

ABSTRACT: The influence of a redox-active ligand on spin changing events induced by coordination of exogenous donors is investigated within the cobalt complex <b>[Co<sup>II</sup>(DPP<sup>•2‒</sup>)]</b>, bearing a redox-active <b>DPP<sup>2‒</sup></b> ligand (DPP = dipyrrin-bis-(<i>o,p</i>-di-tert-butylphenolato) with a pentafluorophenyl moiety on the meso-position. This square planar complex was subjected to coordination of THF, pyridine, tBuNH<sub>2</sub> and AdNH<sub>2</sub> (Ad = 1‑adamantyl), and the resulting complexes were analyzed with a variety of experimental (XRD, NMR, UV-Vis, HRMS, SQUID, Evans’ method) and computational (DFT, NEVPT2-CASSCF) techniques to elucidate the respective structures, spin states and orbital compositions of the corresponding octahedral bis-donor adducts, relative to <b>[Co<sup>II</sup>(DPP<sup>•2‒</sup>)]</b>. This starting species is best described as an open-shell singlet complex containing a <b>DPP<sup>•2‒</sup></b> ligand radical that is antiferromagnetically coupled to a low-spin (S = ½) cobalt(II) center. The redox-active <b>DPP<sup>n‒</sup></b> ligand plays a crucial role in stabilizing this complex, and in its facile conversion to the triplet THF-adduct <b>[Co<sup>II</sup>(DPP<sup>•2‒</sup>)(THF)<sub>2</sub>]</b> and closed-shell singlet pyridine and amine adducts <b>[Co<sup>III</sup>(DPP<sup>3‒</sup>)(L)<sub>2</sub>]</b> (L = py, tBuNH<sub>2</sub> or AdNH<sub>2</sub>). Coordination of the weak donor THF to <b>[Co<sup>II</sup>(DPP<sup>•2-</sup>)]</b> changes the orbital overlap between the <b>DPP<sup>•2‒</sup></b> ligand radical π-orbitals and the cobalt(II) metalloradical d-orbitals, which results in a spin-flip to the triplet ground state without changing the oxidation states of the metal or <b>DPP<sup>•2‒</sup></b> ligand. In contrast, coordination of the stronger donors pyridine, tBuNH<sub>2</sub> or AdNH<sub>2</sub> induces metal-to-ligand single-electron transfer, resulting in formation of low-spin (S = 0) cobalt(III)-complexes <b>[Co<sup>III</sup>(DPP<sup>3‒</sup>)(L)<sub>2</sub>]</b> containing a fully reduced <b>DPP<sup>3‒</sup></b> ligand, thus explaining their closed-shell singlet electronic ground states.

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