Bruce S. Ault

Bio: Bruce S. Ault is an academic researcher from University of Cincinnati. The author has contributed to research in topics: Matrix isolation & Infrared spectroscopy. The author has an hindex of 30, co-authored 269 publications receiving 4190 citations. Previous affiliations of Bruce S. Ault include University of Virginia.

Absorption spectra of matrix‐isolated alkaline earth metal diatomic molecules

Abstract: Mg, Ca, and Sr atoms were codeposited with argon and krypton at 10 K for optical absorption investigation of the van der Waals diatomic molecules. Very strong and weak structured absorptions were observed for Mg2 at 367 and 444 nm, respectively. An unstructured 507 nm and a strong structured 648 nm absorption were found for Ca2, and a strong structured 710 nm absorption was observed for Sr2. Intermediate absorptions with intermediate spacings were observed for CaMg, SrMg, and SrCa in mixed‐metal experiments. The strong absorptions are assigned to 1Σ+u(1S+1P) ←1Σ+g(1S+1S) transitions.

Absorption and emission spectra of matrix‐isolated XeF, KrF, XeCl, and XeBr

Abstract: Argon matrix samples of Kr/F2, Xe/F2, Xe/Cl2, and Xe/Br2 have been photolyzed at 20 K. Emission spectra using uv excitation and uv absorption spectra following photolysis are assigned to the KrF, XeF, XeCl, and XeBr molecules. Vibrational spacings on two KrF and two XeF absorption bands are near RbF and CsF values, which supports the ionic model for the excited states. The vibronic KrF and XeF absorptions, and two very sharp XeCl bands, indicate ground state potential function minima near the ionic excited state values. This suggests that chemical bonding effects are significant in ground state KrF, XeF, and XeCl.

Infrared and Raman spectra of the M+Cl3− ion pairs and their chlorine–bromine counterparts isolated in argon matrices

Abstract: The argon matrix reactions of alkali chloride salts with Cl2 have been investigated through infrared and Raman spectra. In each infrared experiment, an intense product band was observed between 327 and 375 cm−1 and assigned to the antisymmetric stretching vibration ν3 of the Cl3− anion in the ion pair M+Cl3−. Raman spectra of these reaction mixtures yielded the same ν3 bands and, in addition, new signals between 253 and 276 cm−1 which are assigned to the symmetric stretching vibration ν1 of Cl3− in the M+Cl3− species. The observation of two stretching modes in the Raman spectra indicates that the Cl3− ions are asymmetric in these ion pairs. Bromine counterparts and the mixed chlorine–bromine anions were also formed, and used to verify that the anion in the M+X3− species contains three halogen atoms, with the metal ion beside the anion in an asymmetric ’’T’’ shaped structure.

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.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

Abstract: Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy

Abstract: The review covers the knowledge on photoremovable protecting groups and includes all relevant chromophores studied in the time period of 2000–2012; the most relevant earlier works are also discussed.