Search results for "ionization"

Recent developments in resonance ionization mass spectrometry for ultra-trace analysis of actinide elements

2019

Abstract Resonance ionization mass spectrometry is an efficient tool to detect minute amounts of long-lived radio-isotopes in environmental samples. Applying resonant excitation and ionization with pulsed laser radiation within a hot cavity atomizer enables the sensitive detection and precise quantification of long-lived actinide isotopes. Due to the inherently element selective ionization process, this method ensures ultimate suppression of contaminations from other elements and molecules. The characterization of in-source resonance ionization of the actinide elements U, Th, Np, and Am using a compact quadrupole mass spectrometer (QMS) setup are discussed.

Some Observations on Recent Studies Concerning the Electron Ionization Mass Spectrometry of 4(3H)-Quinazolinones

1996

Studies in organic mass spectrometry. Part 24† Electron ionization mass spectra of some aryl(2-nitrobenzo[b]thiophen-3-yl)amines

1999

The main fragmentation routes of eighteen title compounds and of three 5-chloro derivatives have been investigated with the aid of linked scan (B/E = constant) spectrometry, accurate mass measurements and deuterium labelling. Copyright © 1999 John Wiley & Sons, Ltd.

A Comparative Analysis of the Electrophilicity of Organic Molecules between the Computed IPs and EAs and the HOMO and LUMO energies

2007

[EN] The electrophilicity index, omega, of a series of substituted ethylenes used in some relevant organic reactions has been evaluated from the ionization potential JP) and the electron affinity (EA) computed by vertical ionization at the B3LYP/aug-cc-PVTZ level. The corresponding electrophilicity values are well correlated with those obtained from the HOMO and LUMO energies of the neutral molecules. The good linear correlation found between omega(I,A) and omega(H,L)(LBS), and between omega(H,L)(LBS) and omega(H,L)(SBS) allows to confirm the use of the easily available B3LYP/6-31G(*) HOMO and LUMO energies to obtain reasonable values of the global electrophilicity index of organic molecule…

A semi-empirical extrapolation technique for atomic and molecular properties derived from correlated wavefunctions

1976

Abstract A semi-empirical extrapolation technique is suggested for recovering the correlation defect remaining in atomic and molecular properties calculated from highly correlated wavefunctions. These procedures are applied to PNO-CEPA and PNO-IPPA calculations on F, F + , F − , and HF in order to obtain “exact” estimates of the ionization potential, electron affinity, and dissociation energy.

Cooperatively Enhanced Ion Pair Binding with a Hybrid Receptor

2015

A simple 18-crown-6-based bis-urea receptor R(1) was synthesized in three steps from a commercial starting material. The receptor's behavior toward anions, cations, and ion pairs was studied in solution with (1)H NMR, in solid state with single-crystal X-ray diffraction, and in gas phase with mass spectrometry. In 4:1 CDCl3/dimethyl sulfoxide solution the receptor's binding preference of halide anions is I(-) < Br(-) < Cl(-) following the trend of the hydrogen-bonding acceptor ability of the anions. The receptor shows a remarkable positive cooperativity toward halide anions Cl(-), Br(-), and I(-) when complexed with Na(+), K(+), or Rb(+). The solid-state binding modes of R(1) with alkali an…

Resonance ionization spectroscopy of fermium (Z=100)

2003

Laser spectroscopy has been applied for the first time to measure resonant transition frequencies of fermium (Zs 100). A number of 2.7=10 atoms was electrodeposited on a Ta filament and covered with a 1 mm Ti layer. Fm 10

Theoretical spectroscopic parameters of the alkali monofluorides LiF, NaF and KF

1992

Abstract Multireference configuration interaction and second-order perturbation theory are used to determine accurate spectroscopic parameters for the ground state of the alkali monofluorides from LiF to KF. Systematic saturation of the spdf subspaces of the atomic basis sets for the electron affinity of fluorine and the ionization potential of the metals have been shown to be more efficient than for the approximate dissociation energies in the molecule. the calculated rotational and vibrational constants and transitions for the three systems show excellent agreement with the expeirmental data.

Binding Modes of Nonspherical Anions to N-Alkylammonium Resorcinarenes in the Solid State

2012

A series of hydrogen bond stabilized N-alkylammonium resorcinarene salts with nitrate, triflate, and picrate as the counteranions were synthesized and characterized with 1H NMR and electrospray ionization (ESI) mass spectrometry. Together with electrostatic interactions, the binding of the anions with several hydrogen bond donor sites proceeds through a complex array of intra- and intermolecular hydrogen bonds, evidenced by single crystal X-ray diffraction analysis. These N-alkyl ammonium resorcinarenes bind the larger nonspherical anions into deformed cavitand-like structures and enforce a transformation of the resorcinarene conformation from almost symmetrical to extremely distorted.

Electrospray Ionization Mass Spectrometry Studies on the Mechanism of Hydrosilylation of Terminal Alkynes Using an N-Heterocyclic Carbene Complex of …

2006

A new pyridine-4,5-dichloroimidazol-2-ylidene complex of Ir(I) has been obtained, and its catalytic activity toward hydrosilylation of phenylacetylene and 4-aminophenylacetylene has been studied. T...