: 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

N-heterocyclic carbene analogues with low-valent group 13 and group 14 elements: syntheses, structures, and reactivities of a new generation of multitalented ligands.

Hot compressed water (HCW, here water above 200 °C) possesses very interesting properties This series of articles gives an overview of the state of the art as regards the understanding of reactions in HCW In the first part the macroscopic and microscopic properties of HCW will be described, followed by a summary of synthesis reactions published The impact of the unique properties shall be discussed in part II, with the thermal degradation of tert-butylbenzene and the oxidation of methanol being used as examples The studies reported will show that the microscopic properties are of more importance to understanding reactions in HCW than assumed in the past

Hot compressed water as reaction medium and reactant properties and synthesis reactions

Chemical Science Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352; Department of Chemistry, ShelbyHall, University of Alabama, Box 870336, Tuscaloosa, Alabama 35487-0336; Notre Dame Radiation Laboratory, University of Notre Dame,Notre Dame, Indiana 46556; Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 0520-8107; Argonne NationalLaboratory, 9700 South Cass Avenue, Argonne, Illinois 60439; Department of Computer Science and Department of Physics, 2710 University Drive,Washington State University, Richland, Washington 99352-1671; Lawrence Berkeley National Laboratory, 1 Cyclotron Road Mailstop 1-0472,Berkeley, California 94720; Department of Chemistry and Biochemistry, University of Texas at Austin, 1 University Station A5300,Austin, Texas 78712; Office of Basic Energy Sciences, U.S. Department of Energy, SC-141/Germantown Building, 1000 Independence Avenue,S.W., Washington, D.C. 20585-1290; Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson,Hoboken, New Jersey 07030; Department of Chemistry, Johns Hopkins University, 34th and Charles Streets, Baltimore, Maryland 21218;Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062; Department of Chemistry, The Ohio StateUniversity, 100 West 18th Avenue, Columbus, Ohio 43210-1185; Department of Chemistry, Columbia University, Box 3107, Havemeyer Hall,New York, New York 10027; Department of Chemistry, University of Pittsburgh, Parkman Avenue and University Drive,Pittsburgh, Pennsylvania 15260; Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000; Department of Physics andAstronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854-8019; Department of Chemistry,516 Rowland Hall, University of California, Irvine, Irvine, California 92697-2025; Stanford Synchrotron Radiation Laboratory, Stanford LinearAccelerator Center, 2575 Sand Hill Road, Mail Stop 69, Menlo Park, California 94025; School of Chemistry and Biochemistry, Georgia Institute ofTechnology, 770 State Street, Atlanta, Georgia 30332-0400; Geology Department, University of California, Davis, One Shields Avenue,Davis, California 95616-8605; Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue,Cambridge, Massachusetts 02139-4307; Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084Received July 23, 2004

http://casey.brown.edu/chemistry/research/LSWang/publications/194.pdf

Role of water in electron-initiated processes and radical chemistry: issues and scientific advances.

A quantitative theory of the isotropic electron‐nuclear spin interactions of carbon 13 in pi‐electron radicals is presented and applied to the hyperfine splittings observed in the electron spin resonance spectra of these substances. The splittings arise from sigma‐pi interactions which polarize both the 1s and 2s electrons. The 1s‐orbital spin polarization is shown to contribute a term of negative sign with a magnitude comparable to that from the 2s electrons. For an sp2 hybridized carbon atom that is bonded to three atoms, Xi (i=1, 2, 3), the hyperfine constant aC has the form aC=(SC+ ∑ i=13QCXiC)ρπ+ ∑ i=13QXiCCρiπ, where ρπ and ρiπ(i=1,2,3) are the pi‐electron spin densities on atoms C and Xi, respectively. The contribution of the 1s electrons is determined by SC and that of the 2s electrons by the Q's, where QBCA is the sigma‐pi parameter for the nucleus of atom A resulting from the interaction between the bond BC and the pi‐electron spin density on atom B. Calculations for a planar CHC2 fragment model...

THEORETICAL INTERPRETATION OF CARBON-13 HYPERFINE INTERACTIONS IN ELECTRON SPIN RESONANCE SPECTRA. Technical Note Report No. 9

The chemistry of muonium, a light isotope of hydrogen, is investigated for the time period immediately after stopping of its precursor, the positive muon, in the condensed phase. Information is extracted from the initial amplitudes of the muon precession signals arising from muonium and muon-substituted diamagnetic compounds. In liquid water part of the initial spin polarization cannot be accounted for in terms of existing models of muonium formation and reaction. This missing fraction is postulated to arise via a spin exchange interaction of muonium with a hydrated electron. It is also suggested that the chemical fate of the muon is determined by reactions with transient species created in the terminal spur of the muon track.

Radiolysis effects in muonium chemistry

Further improvements to the pulsed EPR spectrometer of Huisjen and Hyde [Rev. Sci. Instrum. 45, 669 (1974)] are described. Special attention is given to techniques for separation of free‐induction‐decay and saturation‐recovery signals. The instrument is suitable for determination of spin‐lattice relaxation times as short as 10−7 sec, and is designed particularly for measurements on dilute solutions of free radicals and of spin‐labeled biomolecules. Analytical solutions of the Bloch equations are obtained that are appropriate for this instrument. The predictions of the equations have been verified by comparison with experiments on the tetracyanoethylene (TCNE) radical anion.

Pulsed EPR spectrometer, II

Muonium-substituted transient radicals observed by muon spin rotation

Saturation-recovery measurements of the spin-lattice relaxation times of some nitroxides in solution

The hyperfine (hf) couplings of all the $^{19}\mathrm{F}$ nuclei in the muonated free radical\ensuremath{\cdot}${\mathrm{C}}_{6}$${\mathrm{F}}_{6}$-Mu have been measured using a level-crossing-resonance technique. Slow damped oscillations of the muon spin polarization in a large longitudinal magnetic field or frequency splittings in transverse field occur at particular field values at which there is a near degeneracy in the muon fluorine hf levels. Thus a resonantlike effect is observed in the muon-spin-rotation spectrum as a function of magnetic field. The positions of such level-crossing resonances allow an accurate determination of the magnitude and sign of the fluorine hf parameters relative to the muon hf parameter.

Paul W. Percival

Papers

Radiolysis effects in muonium chemistry

Pulsed EPR spectrometer, II

Muonium-substituted transient radicals observed by muon spin rotation

Saturation-recovery measurements of the spin-lattice relaxation times of some nitroxides in solution

Resolved nuclear hyperfine structure of a muonated free radical using level-crossing spectroscopy.