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.

Reactions of Laser-Ablated Vanadium Atoms with Dioxygen. Infrared Spectra of VO, VO2, OOVO2, and V2O2 in Solid Argon

Abstract: Laser-ablated V atoms react with O2 to give primarily the bent VO2 dioxide molecule and a smaller yield of the monoxide VO. The OVO valence angle is estimated as 118 ± 3° from oxygen isotopic ν3 fr...

Significant Interactions between Uranium and Noble‐Gas Atoms: Coordination of the UO2+ Cation by Ne, Ar, Kr, and Xe Atoms

Abstract: Laser-ablated uranium cation reacts with O2 to give UO2+, which is found to form UO2+(Ng)n (Ng = Ne, Ar, Kr, Xe) complexes on condensation with excess noble gas. Experiments with mixtures of noble gases lead to five new absorptions for the mixed UO2+(Ng)x(Ng')y complexes and show that the coordination number is five for Ng = Ar, Kr, and Xe. These results are consistent with predictions by relativistic density functional calculations and indicate significant bonding between U and noble-gas atoms.

FTIR spectra of hydrogen fluoride complexes in solid argon

Abstract: Les molecules HF sont codeposees avec des bases dans le domaine de forces de N 2 a N(CH 3 ) 3 avec de l'argon en exces a 12 K. Les spectres mettent en evidence des complexes lies par liaison hydrogene de stœchiometrie 1:1 et 1:2. Discussion

Reactions of Laser-Ablated Iron Atoms with Oxygen Molecules: Matrix Infrared Spectra and Density Functional Calculations of OFeO, FeOO, and Fe(O2)

Abstract: Reactions of laser-ablated Fe atoms and O2 molecules in argon condensing on a 10 K surface have produced sharp infrared absorptions at 1204.5, 945.6, and 797.1 cm-1 that are identified as FeOO and OFeO, respectively, through the use of isotopic substitution and DFT structure and isotopic frequency calculations. Annealing to 30 and 50 K produced a strong 956.0-cm-1 band, which is due to cyclic Fe(O2); visible photolysis destroyed the 1204.5-cm-1 FeOO band, but it was regenerated on annealing. Formation of the more stable dioxo insertion product OFeO requires activation energy whereas the superoxo and peroxo addition products FeOO and Fe(O2) can be formed on diffusion of cold reagents in solid argon. The FeOO spectrum observed and calculated here compares favorably with those reported for oxyhemoproteins, which provides further support for the Fe−O−O binding geometry in these biologically important metalloproteins.

A Chemist's Guide to Density Functional Theory

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.

The density functional formalism, its applications and prospects

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.

The Halogen Bond

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.

Generation and Detection of Reactive Oxygen Species in Photocatalysis

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...

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

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