217 research outputs found
Comparison of Conventional and Nonconventional Hydrogen Bond Donors in Au<sup>-</sup> Complexes
Although gold has become a well-known nonconventional hydrogen bond acceptor, interactions with nonconventional hydrogen bond donors have been largely overlooked. In order to provide a better understanding of these interactions, two conventional hydrogen bonding molecules (3-hydroxytetrahydrofuran and alaninol) and two nonconventional hydrogen bonding molecules (fenchone and menthone) were selected to form gas-phase complexes with Au-. The Au-[M] complexes were investigated using anion photoelectron spectroscopy and density functional theory. Au-[fenchone], Au-[menthone], Au-[3-hydroxyTHF], and Au-[alaninol] were found to have vertical detachment energies of 2.71 ± 0.05, 2.76 ± 0.05, 3.01 ± 0.03, and 3.02 ± 0.03 eV, respectively, which agree well with theory. The photoelectron spectra of the complexes resemble the spectrum of Au- but are blueshifted due to the electron transfer from Au- to M. With density functional theory, natural bond orbital analysis, and atoms-in-molecules analysis, we were able to extend our comparison of conventional and nonconventional hydrogen bonding to include geometric and electronic similarities. In Au-[3-hydroxyTHF] and Au-[alaninol], the hydrogen bonding comprised of Au-···HO as a strong, primary hydrogen bond, with secondary stabilization by weaker Au-···HN or Au-···HC hydrogen bonds. Interestingly, the Au-···HC bonds in Au-[fenchone] and Au-[menthone] can be characterized as hydrogen bonds, despite their classification as nonconventional hydrogen bond donors
Infrared action spectroscopy of nitrous oxide on cationic gold and cobalt clusters
Understanding the catalytic decomposition of nitrous oxide on finely divided transition metals is an important environmental issue. In this study, we present the results of a combined infrared action spectroscopy and quantum chemical investigation of molecular N2O binding to isolated Aun+ (n ≤ 7) and Con+ (n ≤ 5) clusters. Infrared multiple-photon dissociation spectra have been recorded in the regions of both the N=O (1000–1400 cm-1) and N=N (2100–2450 cm-1) stretching modes of nitrous oxide. In the case of Aun+ clusters only the ground electronic state plays a role, while the involvement of energetically low-lying excited states in binding to the Con+ clusters cannot be ruled out. There is a clear preference for N-binding to clusters of both metals but some O-bound isomers are observed in the case of smaller Con(N2O)+ clusters
Excited States of Proton-bound DNA/RNA Base Homo-dimers: Pyrimidines
We are presenting the electronic photo fragment spectra of the protonated
pyrimidine DNA bases homo-dimers. Only the thymine dimer exhibits a well
structured vibrational progression, while protonated monomer shows broad
vibrational bands. This shows that proton bonding can block some non radiative
processes present in the monomer.Comment: We acknowledge the use of the computing facility cluster GMPCS of the
LUMAT federation (FR LUMAT 2764
The Citation Field of Evolutionary Economics
Evolutionary economics has developed into an academic field of its own,
institutionalized around, amongst others, the Journal of Evolutionary Economics
(JEE). This paper analyzes the way and extent to which evolutionary economics
has become an interdisciplinary journal, as its aim was: a journal that is
indispensable in the exchange of expert knowledge on topics and using
approaches that relate naturally with it. Analyzing citation data for the
relevant academic field for the Journal of Evolutionary Economics, we use
insights from scientometrics and social network analysis to find that, indeed,
the JEE is a central player in this interdisciplinary field aiming mostly at
understanding technological and regional dynamics. It does not, however, link
firmly with the natural sciences (including biology) nor to management
sciences, entrepreneurship, and organization studies. Another journal that
could be perceived to have evolutionary acumen, the Journal of Economic Issues,
does relate to heterodox economics journals and is relatively more involved in
discussing issues of firm and industry organization. The JEE seems most keen to
develop theoretical insights
Microsecond Isomer at the N=20 Island of Shape Inversion Observed at FRIB
Excited-state spectroscopy from the first Facility for Rare Isotope Beams
(FRIB) experiment is reported. A 24(2)-s isomer was observed with the FRIB
Decay Station initiator (FDSi) through a cascade of 224- and 401-keV
rays in coincidence with nuclei. This is the only known
microsecond isomer () in the
region. This nucleus is at the heart of the island of shape inversion
and is at the crossroads of spherical shell-model, deformed shell-model, and ab
initio theories. It can be represented as the coupling of a proton hole and
neutron particle to , .
This odd-odd coupling and isomer formation provides a sensitive measure of the
underlying shape degrees of freedom of , where the onset of
spherical-to-deformed shape inversion begins with a low-lying deformed
state at 885 keV and a low-lying shape-coexisting state at 1058 keV. We
suggest two possible explanations for the 625-keV isomer in Na: a
spherical shape isomer that decays by or a deformed spin isomer that
decays by . The present results and calculations are most consistent with
the latter, indicating that the low-lying states are dominated by deformation.Comment: 7 pages, 5 figures, accepted by Physical Review Letter
Environmental innovation and socio-economic dynamics in institutional and policy contexts
Clinical and In Vitro Studies on Impact of High-Dose Etoposide Pharmacokinetics Prior Allogeneic Hematopoietic Stem Cell Transplantation for Childhood Acute Lymphoblastic Leukemia on the Risk of Post-Transplant Leukemia Relapse
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