Viewpoint pubs.acs.org/JPCA
Recent Advancements in Chemical Physics
I
They play important roles in areas of hydrogen storage and lithium ion batteries [Chem. Phys. Chem. 2011, 12, 2422]. Carl Lineburger (University of Colorado and JILA) presented a detailed discussion of photoelectron spectroscopy of the pyramidal CH3− anion, forming the planar CH3 radical. Velocity-mapped image (VMI) photoelectron spectroscopy was employed to obtain the anion ammonia-like inversion splitting, as well as a very accurate electron affinity of the methyl radical [J. Am. Chem. Soc. 2015, 137, 12939]. This system is analogous to Compton’s seminal investigations of the bent carbon dioxide anion. Michael Duncan (University of Georgia), a long time collaborator and friend of Compton, highlighted advancements in molecular ion spectroscopy when coupled with mass spectrometry, starting with the infrared spectra of solvated transition metal clusters, M+(H2O)n, and including the protonated water clusters, H+(H2O)n. He also detailed his group’s recent demonstration of a photofragment imaging instrument for probing cluster ions, including Ag+(benzene) [J. Phys. Chem. Lett. 2015, 6, 4493]. In addition to his contributions to the field of chemical physics, Bob Compton has always exhibited a passion for chemical education in the physical sciences. Over the years, Compton and Duncan have worked together to develop laser-based laboratory experiments to compliment undergraduate and graduate level physical chemistry and chemical physics courses. Compton discussed some of these experiments, which can now be found in the new collection, Laser Experiments for Chemistry and Physics, Oxford University Press, 2016. This textbook also includes fundamental characteristics and operation of lasers, backgrounds in optics and spectroscopy, and proper safety precautions. Prasad L. Polavarapu (Vanderbilt University) presented new advancements in 3D structural determination of chiral molecules and provided insight into the importance in recent years. Though X-ray crystallography has been one of the main techniques used for this purpose, the need for growing goodquality crystals limits the use of this method. Recent developments in spectroscopic instrumentation for measuring chiroptical spectra and quantum theoretical developments for predicting chiroptical spectra have revolutionized the field of chiroptical spectroscopy. Charles Feigerle (University of Tennessee) wrapped up the first day of the session by sharing some of his experiences with Compton over the years at the University of Tennessee and ORNL and also the value of Compton’s contributions to the field and other researchers through the years. While the second day of the session focused on solid state physics and molecular ion spectroscopy, the third day of the symposium concentrated on theoretical and computational chemistry. Thomas Sommerfeld (Southeastern Louisiana University) discussed collaborative efforts with Compton over the years describing the states formed upon excess electron attachment to molecules and clusters. This included a
n honor of the career of Professor Robert (Bob) N. Compton, a special three-day symposium focusing on recent advances in chemical physics, including gaseous ion chemistry and electronic structure theory, was held at the 67th Southeastern Regional Meeting of the American Chemical Society (SERMACS) in Memphis, TN. The session was organized by Nathan I. Hammer (University of Mississippi) with help from Gregory S. Tschumper (University of Mississippi) and Kit H. Bowen (Johns Hopkins University). The organizers invited a number of esteemed speakers, including many who collaborated with Prof. Compton over the years or worked with him at the University of Tennessee and Oak Ridge National Laboratory (ORNL). This article summarizes the material presented by the invited speakers and acknowledges the successful career of Bob Compton. The symposium started on Wednesday, November 4th, with 12 contributed talks, mostly from graduate students. The morning session on Thursday, November 5th, began with a presentation on the spectral signatures of domain walls in inorganic complexes by a fellow University of Tennessee chemical physics colleague, Janice Musfeldt. She discussed the spectroscopic comparison between vertex- and stripe-containing ErMnO3 and how it provides insight into the electronic properties of multiferroics [Phys. Rev B 2014, 90, 121303R]. E. Ward Plummer (Louisiana State University) presented complementary spectroscopic techniques for the characterization of crystalline materials. By employing second-order nonlinear spectroscopies, such as second harmonic generation (SHG) and femtosecond broadband sum frequency generation (SFG), results suggest improved sensitivity when monitoring a molecular maker (carbon monoxide) vibrational stretching mode. This technique can be generally applied to surface and interface studies of other noncentrosymmetric crystals. Kit Bowen presented details on both historical and recent advancements in the area of negative ion photoelectron spectroscopy. His group has recently focused on unique solvation effects and fixation of CO2 in transition metal anion complexes. The photoelectron data suggested individual character of (M−CO2)−, M = Au, Ag, Cu, cluster anions with respect to either chemisorption or physisorption of the solvating CO2 molecule [J. Chem. Phys. 2015, 143, 174305]. A former graduate student of the Bowen group, Jim Coe from The Ohio State University, followed with a detailed narrative of his work on weakly bound anions, including a discussion of the well-known photoelectron spectra of the hydrated electron cluster anions [J. Chem. Phys. 1990, 92, 3980] and a method for quantifying solvation Gibbs free energies and enthalpies for individual ions which was demonstrated for water and later applied to ammonia [J. Phys. Chem. A 2002, 106, 925]. Puru Jena (Virginia Commonwealth University) delivered an overview on the importance of multiply charged negative ions as well as newly developed organometallic complexes that are much more stable than the classic B12H122− cluster anion. Such novel species are given the names superhalogens and hyperhalogens and exhibit electron affinities as high as 14 eV. © 2015 American Chemical Society
Published: December 31, 2015 12909
DOI: 10.1021/acs.jpca.5b12096 J. Phys. Chem. A 2015, 119, 12909−12910
Viewpoint
The Journal of Physical Chemistry A ‡
discussion of the highly polar molecule p-nitroaniline (pNA), a molecule similar to the chemical analogue nitromethane. These systems are thought to exhibit both valence and dipole-bound character upon excess electron attachment. The theoretical adiabatic electron affinity of pNA (0.73 eV) was shown to be in excellent agreement with the measured value of 0.75 ± 0.1 eV [J. Chem. Phys. 2013, 138, 234304]. Ken Jordan (University of Pittsburgh) connected with attendees by sharing both experimental and theoretical efforts describing negative and positive ions throughout his career, some of which were in collaboration with Compton. Some of his most cited work has been in characterizing protonated water clusters by infrared spectral signatures [Science 2004, 304, 1137 and Science 2005, 308, 1765]. He also discussed his group’s new techniques that describe the products of electron capture to form transient anions. Jordan and Compton share the same appreciation for molecules and clusters that exhibit near zero electron affinities. Gregory Tschumper emphasized the demands of highly accurate and systematically improvable electronic structure methods accompanied by the complete basis set (CBS) limit. His research group focuses on benchmarking harmonic and anharmonic vibrational frequencies for systems that exhibit hydrogen bonding (H2O, HF, and/ or HCl) at the CBS limit with correlated electronic structure methods. The most recent advancement that he discussed is the development of a N-body:Many-body integrated QM:QM method that overcomes the unfavorable scaling of canonical CCSD(T) Hessian computations for noncovalent clusters [J. Chem. Phys. 2013, 139, 184113]. Angela Wilson (University of North Texas) highlighted the significance of main group and nonmain group chemistry by employing DFT and ab initio single reference and multireference methodologies. These computational efforts have been verified with a variety of basis sets for the prediction of structural, energetic, and spectroscopic properties of f-block elements (lanthanide species in the common 3+ oxidation states) [J. Chem. Theory Comput. 2012, 8, 460]. Rodney Bartlett (University of Florida and director of the Quantum Theory Project) delivered an informative discussion involving several new methods for excited states, including TDDFT, EOM-CC, and STEOM-CC. The previously mentioned ab initio and density functional methods focused on core-excitation spectra. Some of his research group’s efforts have developed an ab initio DFT method that is built upon the optimized effective potential strategy for exchange and correlation and is a consistent KSDFT functional. This newly developed method was tested and compared to other KS-DFT functionals for select properties [J. Chem. Phys. 2012, 137, 134102]. This symposium and accompanying symposium dinner would not have been made possible without generous donations from the following supporters: Oak Ridge Associated Universities (ORAU), Cornerstone Laboratories, Coherent, Horiba Scientific, InnoLas Laser, Allied Laser Solutions, Swift Staffing, the University of Mississippi Department of Chemistry and Biochemistry, and the University of Tennessee Department of Chemistry and Department of Physics.
■
Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
AUTHOR INFORMATION
Corresponding Author
*J. T. Kelly. E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
John T. Kelly*,† Jonathan A. Maner‡ Nathan I. Hammer† †
Department of Chemistry and Biochemistry, University of Mississippi, University, Oxford, Mississippi 38677, United States 12910
DOI: 10.1021/acs.jpca.5b12096 J. Phys. Chem. A 2015, 119, 12909−12910
