Charge-Transfer and Energy-Transfer Processes in π-Conjugated Oligomers and Polymers: A Molecular Picture

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

http://alpha.chem.umb.edu/chemistry/ch611/documents/C-Htransitionmetalbonds.pdf

Carbonhydrogen-transition metal bonds

The restricted active space (RAS) state interaction approach with spin-orbit coupling

Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a by-product of the very oxidation chemistry it largely initiates. Much effort is focussed on the reduction of surface levels of ozone owing to its health impacts but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve due to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate-change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner.

/pdf/tropospheric-ozone-and-its-precursors-from-the-urban-to-the-1p9j5d9h0o.pdf

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

The information to be obtained from the study of unstable molecules in the vapour phase by photoelectron spectroscopy is reviewed, using examples drawn from high-temperature pyrolysis experiments and rapid atom-molecule reaction. An example is given of a chemi-ionization reaction studied by electron spectroscopy, and the information to be obtained from such studies is outlined.

Properties of gas-phase ions. Information to be obtained from photoelectron spectroscopy of unstable molecules

2-Azidoacetic acid (N3CH2CO2H) has been synthesized and characterized by a variety of spectroscopic techniques, and the thermal decomposition of this molecule studied by matrix isolation infrared s...

Study of the Thermal Decomposition of 2-Azidoacetic Acid by Photoelectron and Matrix Isolation Infrared Spectroscopy

High-temperature photoelectron spectroscopy: the vanadium monoxide molecule

Products of the gas‐phase reactions M+N2O and M+O3, where M=Na or K, have been investigated with UV photoelectron spectroscopy and bands have been assigned with the assistance of results from ab initio molecular orbital calculations. For the M+N2O reactions, the observed products were MO+N2. Measurement of the photoelectron bands associated with the metal monoxide MO allowed determination of the first adiabatic ionization energies of NaO and KO. The values obtained were AIE[NaO(X 2Π)]=(7.1±0.1) eV and AIE[KO(X 2Π)]=(6.9±0.1) eV. A similar study of the Li+N2O reaction gave AIE[LiO(X 2Π)]=(7.6±0.2) eV. The reactions M+O3, with M=Na or K, were observed to give MO+O2 as the major reaction products. However, for each reaction, a band was observed which was assigned to the first ionization energy of the secondary reaction product MO2. From the spectra obtained, the first adiabatic ionization energies of NaO2 and KO2 were measured as AIE[NaO2(X 2A2)]=(6.2±0.2) eV and AIE[KO2(X 2A2)]=(5.7±0.1) eV. For both the M+...

A Study of the Products of the Gas-Phase Reactions M + N2O and M + O3, Where M = Na or K with Ultraviolet Photoelectron Spectroscopy,

The CF (X 2Π) radical has been investigated with vacuum ultraviolet photoelectron spectroscopy and ab initio molecular orbital calculations. Only one band was observed and it was assigned to the ionization CF+(X 1Σ+)←CF(X 2Π). For this band, the adiabatic and vertical ionization potentials were measured as (9.11±0.01) and (9.55±0.01) eV, respectively, and analysis of the vibrational structure in this band allowed we and re for CF+(X 1Σ+) to be determined as (1840±30) cm−1 and (1.148±0.005) A. Comparison is made with other first row diatomic fluorides that have also been studied with PES.

John M. Dyke

Papers

Properties of gas-phase ions. Information to be obtained from photoelectron spectroscopy of unstable molecules

Study of the Thermal Decomposition of 2-Azidoacetic Acid by Photoelectron and Matrix Isolation Infrared Spectroscopy

High-temperature photoelectron spectroscopy: the vanadium monoxide molecule

A Study of the Products of the Gas-Phase Reactions M + N2O and M + O3, Where M = Na or K with Ultraviolet Photoelectron Spectroscopy,

A photoelectron spectroscopic study of the ground state of CF+ via the ionization process CF+(X 1Σ+)←CF(X 2Π)