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Lester Andrews

Bio: Lester Andrews is an academic researcher from University of Virginia. The author has contributed to research in topics: Infrared spectroscopy & Molecule. The author has an hindex of 68, co-authored 888 publications receiving 24613 citations. Previous affiliations of Lester Andrews include Ames Research Center & Environmental Molecular Sciences Laboratory.


Papers
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Journal ArticleDOI
TL;DR: In this paper, laser-ablated cobalt atoms have been reacted with CO molecules during condensation in excess argon, and the CoCO molecule was observed after deposition, and Co(CO)2,3,4 are formed on annealing in agreement with earlier matrix work.
Abstract: Laser-ablated cobalt atoms have been reacted with CO molecules during condensation in excess argon. The CoCO molecule is observed after deposition, and Co(CO)2,3,4 are formed on annealing in agreement with earlier matrix work. Cobalt carbonyl anions are also produced and trapped. On the basis of isotopic substitution and density functional calculations, a sharp absorption at 1804.0 cm-1 is assigned to the C−O stretching mode of CoCO-, 1768.9 and 1860.2 cm-1 bands to antisymmetric and symmetric C−O stretching vibrations of bent Co(CO)2-, and 1826.9 and 1890.0 cm-1 absorptions to the antisymmetric stretching modes of Co(CO)3- and Co(CO)4-, respectively.

27 citations

Journal ArticleDOI
TL;DR: In this paper, laser-ablated Be atoms and H2O molecules during condensation with excess argon at 10 K gave three new molecules, HOBeOH, HBeOBeH and HOBeOH, which were characterized by matrix infrared observation of isotopic frequencies and density functional theory calculations.
Abstract: Reactions of laser-ablated Be atoms and H2O molecules during condensation with excess argon at 10 K gave three new molecules. The direct insertion product HBeOH was characterized by matrix infrared observation of isotopic frequencies and density functional theory calculations. The major product, HOBeOH, was formed by reaction of water with BeO, made from HBeOH decomposition. Another product, HBeOBeH, was formed by the reaction of a second Be atom with HBeOH.

27 citations

Journal ArticleDOI
TL;DR: In this article, the BP86 functional and 6-311G* basis sets were used to predict the vibrational frequencies of linear beryllium species, including BeNC, BeCN, HBeNC and HBeCN.
Abstract: Laser-ablated beryllium atoms have been reacted with hydrogen cyanide (H12CN, H13CN, and D12CN) during condensation in excess argon at 6−7 K. In the matrix infrared spectrum, the major products observed are BeNC, BeCN, HBeNC, and HBeCN. Consistent with typical beryllium bonding, these new beryllium species are linear molecules. Density functional theory calculations on these products with the BP86 functional and 6-311G* basis sets predict vibrational frequencies extremely well, even for HBeCN where mixing between the nearly isoenergetic Be−H and C⋮N stretching modes causes significant complications in the spectra. Although B3LYP and MP2 calculations are more sophisticated than the BP86 method, they do not predict the vibrational frequencies of these products nearly as well. More important is the carbon 12/13 isotopic frequency ratio as a description of the normal modes, and the BP86 method generates 12/13 ratios much closer to observed values for HBeCN than frequency ratios from the more time-consuming CI...

27 citations

Journal ArticleDOI
TL;DR: In this paper, pulsed laser evaporated magnesium atoms were codeposited with O 2 in excess argon on a 10 K substrate, and the sharp dominant product band a 767.7 cm -1 showed magnesium and oxygen isotopic splittings and shifts in excellent agreement with shifts predicted for linear OMgO.
Abstract: Pulsed laser evaporated magnesium atoms were codeposited with O 2 in excess argon on a 10 K substrate. The sharp dominant product band a 767.7 cm -1 showed magnesium and oxygen isotopic splittings and shifts in excellent agreement with shifts predicted for linear OMgO. Sharp 971.7- and 591.7 cm -1 bands exhibited isotopic shifts appropriate for the linear MgOMgO species. The pulsed laser evaporation process imparts sufficient kinetic energy to Mg atoms to provide the activation energy for insertion into the O 2 molecule

27 citations

Journal ArticleDOI
TL;DR: The 15°K deposition of alkaline earth metal atoms and ozone molecules at high dilution in argon yielded intense bands near 800 cm −1 and in the region, 450-650 cm − 1.

27 citations


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Book
01 Sep 2001
TL;DR: A Chemist's Guide to Density Functional Theory should be an invaluable source of insight and knowledge for many chemists using DFT approaches to solve chemical problems.
Abstract: "Chemists familiar with conventional quantum mechanics will applaud and benefit greatly from this particularly instructive, thorough and clearly written exposition of density functional theory: its basis, concepts, terms, implementation, and performance in diverse applications. Users of DFT for structure, energy, and molecular property computations, as well as reaction mechanism studies, are guided to the optimum choices of the most effective methods. Well done!" Paul von RaguE Schleyer "A conspicuous hole in the computational chemist's library is nicely filled by this book, which provides a wide-ranging and pragmatic view of the subject.[...It] should justifiably become the favorite text on the subject for practioneers who aim to use DFT to solve chemical problems." J. F. Stanton, J. Am. Chem. Soc. "The authors' aim is to guide the chemist through basic theoretical and related technical aspects of DFT at an easy-to-understand theoretical level. They succeed admirably." P. C. H. Mitchell, Appl. Organomet. Chem. "The authors have done an excellent service to the chemical community. [...] A Chemist's Guide to Density Functional Theory is exactly what the title suggests. It should be an invaluable source of insight and knowledge for many chemists using DFT approaches to solve chemical problems." M. Kaupp, Angew. Chem.

3,550 citations

Journal ArticleDOI
TL;DR: In this paper, the authors survey the local density functional formalism and some of its applications and discuss the reasons for the successes and failures of the local-density approximation and some modifications.
Abstract: A scheme that reduces the calculations of ground-state properties of systems of interacting particles exactly to the solution of single-particle Hartree-type equations has obvious advantages. It is not surprising, then, that the density functional formalism, which provides a way of doing this, has received much attention in the past two decades. The quality of the energy surfaces calculated using a simple local-density approximation for exchange and correlation exceeds by far the original expectations. In this work, the authors survey the formalism and some of its applications (in particular to atoms and small molecules) and discuss the reasons for the successes and failures of the local-density approximation and some of its modifications.

3,285 citations

Journal ArticleDOI
TL;DR: The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.
Abstract: The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

2,582 citations

Journal ArticleDOI
TL;DR: The detection methods and generation mechanisms of the intrinsic reactive oxygen species (ROS) in photocatalysis were surveyed comprehensively and the major photocatalyst used in heterogeneous photocatalytic systems was found to be TiO2.
Abstract: The detection methods and generation mechanisms of the intrinsic reactive oxygen species (ROS), i.e., superoxide anion radical (•O2–), hydrogen peroxide (H2O2), singlet oxygen (1O2), and hydroxyl radical (•OH) in photocatalysis, were surveyed comprehensively. Consequently, the major photocatalyst used in heterogeneous photocatalytic systems was found to be TiO2. However, besides TiO2 some representative photocatalysts were also involved in the discussion. Among the various issues we focused on the detection methods and generation reactions of ROS in the aqueous suspensions of photocatalysts. On the careful account of the experimental results presented so far, we proposed the following apprehension: adsorbed •OH could be regarded as trapped holes, which are involved in a rapid adsorption–desorption equilibrium at the TiO2–solution interface. Because the equilibrium shifts to the adsorption side, trapped holes must be actually the dominant oxidation species whereas •OH in solution would exert the reactivity...

2,249 citations

01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : 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

1,652 citations