Search results for "PolyAT"
showing 10 items of 53 documents
Ionization dynamics of a model molecular ion
2005
We study the ionization dynamics of a model one-dimensional molecular ion as a function of the internuclear distance R, for different values of the laser intensity. The electron–nucleus potential is assumed to be a Poschl–Teller potential, whose parameters are chosen to have only two bare bound molecular states in the range of R considered. We describe three different theoretical approaches to study the dynamics of the system: an exact numerical, a semiperturbative and a phenomenological approach. All these approaches indicate the presence of a sharp ionization peak for a critical value of the internuclear distance, for which the energy difference between the two bound levels coincides with…
Ferro- and Antiferromagnetic Interactions in Oxalato-Centered Inverse Hexanuclear and Chain Copper(II) Complexes with Pyrazole Derivatives.
2021
Two novel copper(II) complexes of formulas {[Cu(4-Hmpz)4][Cu(4-Hmpz)2(µ3-ox-κ2O1,O2:κO2′:κO1′)(ClO4)2]}n (1) and {[Cu(3,4,5-Htmpz)4]2[Cu(3,4,5-Htmpz)2(µ3-ox-κ2O1,O2:κO2′:κO1′)(H2O)(ClO4)]2[Cu2(3,4,5-Htmpz)4(µ-ox-κ2O1,O2:κ2O2′,O1′)]}(ClO4)4·6H2O (2) have been obtained by using 4-methyl-1H-pyrazole (4-Hmpz) and 3,4,5-trimethyl-1H-pyrazole (3,4,5-Htmpz) as terminal ligands and oxalate (ox) as the polyatomic inverse coordination center. The crystal structure of 1 consists of perchlorate counteranions and cationic copper(II) chains with alternating bis(pyrazole)(µ3-κ2O1,O2:κO2′:κO1′-oxalato)copper(II) and tetrakis(pyrazole)copper(II) fragments. The crystal structure of 2 is made up of perchlorat…
A new general fragmentation reaction in mass spectrometry: The hydrogen-carbon, carbon-carbon double rearrangement of 2 heteroalkyl substituted diphe…
1995
Diphenylmethyl cations formed by benzylic cleavage of the molecular ions of ortho heteroalkyl substituted 1,1-diphenylalkanes undergo the double rearrangement process (H to C followed by C to C) previously reported for ortho-methoxy derivatives. Hence the formation of substituted benzyl (or tropylium) ions allowing this double rearrangement process constitutes an interesting type of fragmentation reaction characteristic for 1,1-diphenylalkanes bearing ortho substituents (OMe, OEt, OiPr, SMe, NHMe, NMe2) which are able to transfer a hydride to the charged benzyl carbon of diphenylmethyl cations formed by benzylic cleavage of the molecular ion.
Glycosylamines of 4,6-O-butylidene-α-d-glucopyranose: synthesis and characterization of glycosylamines, and the crystal structure of 4,6-O-butylidene…
2002
A total of nine glycosylamines of 4,6-O-butylidene-α-D-glucopyranose were synthesized using primary amines having various groups in their ortho- or para-positions. Among these, six are monoglycosylamines, including one primary glycosylamine, and three are bis-glycosylamines. All these compounds were characterized by 1H, 1H–1H COSY, 1H–13C COSY and 13C NMR spectroscopy and FTIR spectra. The FAB mass spectra provided the molecular weights of the products by exhibiting the corresponding molecular ion peaks. The crystal structure of 4,6-O-butylidene-N-(o-chlorophenyl)-β-D-glucopyranosylamine revealed the C-1 glycosylation, the β-anomeric nature, and the 4C1 chair conformation of the saccharide …
Ag44(SeR)30: A Hollow Cage Silver Cluster with Selenolate Protection.
2015
Selenolate protected, stable and atomically precise, hollow silver cluster was synthesized using solid state as well as solution state routes. The optical absorption spectrum shows multiple and sharp features similar to the thiolated Ag44 cluster, Ag44(SR)30 whose experimental structure was reported recently. High-resolution electrospray ionization mass spectrometry (HRESI MS) shows well-defined molecular ion features with two, three, and four ions with isotopic resolution, due to Ag44(SePh) 30. Additional characterization with diverse tools confirmed the composition. The closed-shell 18 electron superatom electronic structure, analogous to Ag44(SR)30 stabilizes the dodecahedral cage with a…
The Crucial Role of Polyatomic Anions in Molecular Architecture: Structural And Magnetic Versatility of Five Nickel(II) Complexes Derived from A N,N,…
2009
Five new nickel(II) complexes [Ni(2)L(2)(N(3))(2)(H(2)O)(2)] (1), [Ni(2)L(2)(NO(3))(2)] (2), [Ni(2)L(2)(O(2)CPh)(CH(3)OH)(2)]ClO(4).0.5CH(3)OH (3), [Ni(3)L(2)(O(2)CPh)(4)] (4), and [Ni(2)L(2)(NO(2))(2)](n) (5) have been synthesized by using a tridentate Schiff base ligand, HL (2-[(3-Methylamino-propylimino)-methyl]-phenol), and the polyatomic monoanions N(3)(-), NO(3)(-), PhCOO(-), or NO(2)(-). The complexes have been structurally and magnetically characterized. The structural analysis reveals that in all five complexes, the Ni(II) ions possess a distorted octahedral geometry. Complexes 1 and 2 are dinuclear with di-mu-1,1-azido and di-mu(2)-phenoxo bridges, respectively. Complex 3 is also …
Selected dissociation‐ and correlation‐consistent configuration interaction by a perturbative criterion
1990
We propose a perturbative criterion to select the most important dissociation‐ or correlation‐consistent type of contributions to perform generalized valence bond‐configuration interaction (GVB‐CI) calculations, dissociation‐consistent configuration interaction (DCCI) or correlation‐consistent configuration interaction (CCCI) approach, respectively. The procedure presented is computationally less demanding than the CCCI proposed by Goddard and co‐workers. To ensure the distance consistency of the MOs used, the nonvalence virtual orbitals are obtained by a projection technique. The results obtained for a few test calculations show the ability of the suggested approach to get close results to…
Determination of dissociation energies by use of energy-dependent decay pathway branching ratios
2001
Abstract We present a method for the determination of dissociation energies of polyatomic systems that undergo sequential fragmentation with energy-dependent decay pathway branching. It allows to experimentally determine the dissociation energy of any polyatomic system that shows such fragmentation behaviour without the need for a specific modelling of the system or of its fragmentation process, thus eliminating several systematic errors of traditional methods. The new method has been applied to the sequential fragmentation of Au+14 and Au+16. The resulting dissociation energies are highly accurate and in good agreement with model-free values based on rates of sequential decays.
Multielemental determination of trace mineral elements in seawater by dynamic reaction cell inductively coupled plasma- mass spectrometry after Al(OH…
2020
Abstract A simple method has been developed for the simultaneous determination of 12 trace mineral elements in seawater using, in some cases, several target isotopes (51V, 52Cr, 55Mn, 58,60Ni, 59Co, 63,65Cu, 64,66,68Zn, 75As, 78Se, 111,113Cd, 206,207,208Pb y 238U) in seawater. The method combined a simple and fast Al(OH)3 co-precipitation method, to pre-concentrate mineral elements and to separate them from the seawater matrix, and inductively coupled plasma mass spectrometry using the dynamic reaction cell with NH3 gas to do quantitative determinations free from polyatomic interferences. The recoveries of trace elements after Al(OH)3 co-precipitation varies between 80% for 111Cd and 116% f…
Strong thermal nonequilibrium in hypersonic CO and CH4 probed by CRDS
2015
A new experimental setup coupling a High Enthalpy Source (HES) reaching 2000 K to a cw-cavity ring-down spectrometer has been developed to investigate rotationally cold hot bands of polyatomic molecules in the [1.5, 1.7] μm region. The rotational and vibrational molecular degrees of freedom are strongly decoupled in the hypersonic expansion produced by the HES and probed by cavity ring-down spectroscopy. Carbon monoxide has been used as a first test molecule to validate the experimental approach. Its expansion in argon led to rotational and vibrational temperatures of 6.7 ± 0.8 K and 2006 ± 476 K, respectively. The tetradecad polyad of methane (1.67 μm) was investigated under similar condit…