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David J Kemp, Laura E Whalley, Adrian M Gardner, William D Tuttle, Lewis G Warner, Timothy G Wright
Two-dimensional laser-induced fluorescence (2D-LIF) spectroscopy is a powerful tool allowing overlapped features in an electronic spectrum to be separated, and interactions between vibrations and torsions to be identified. Here the technique is employed to assign the 790-825 cm-1 region above the origin of the S1 ← S0 transition in para-fluorotoluene, which provides insight into the unusual time-resolved results of Davies and Reid [Phys. Rev. Lett. 109, 193004 (2012)]. The region is dominated by a pair of bands that arise from a Fermi resonance; however, the assignment is complicated by contributions from a number of overtones and combinations, including vibration-torsion ("vibtor") levels...
February 14, 2019: Journal of Chemical Physics
Ruslan L Davidchack, Brian B Laird
No abstract text is available yet for this article.
February 14, 2019: Journal of Chemical Physics
David Picconi, Jeffrey A Cina, Irene Burghardt
This study presents quantum dynamical simulations, using the Gaussian-based multiconfigurational time-dependent Hartree (G-MCTDH) method, of time-resolved coherent Raman four-wave-mixing spectroscopic experiments for the iodine molecule embedded in a cryogenic crystal krypton matrix [D. Picconi et al., J. Chem. Phys. 150, 064111 (2019)]. These experiments monitor the time-evolving vibrational coherence between two wave packets created in a quantum superposition (i.e., a "Schrödinger cat state") by a pair of pump pulses which induce electronic B Πu30+ ⟵XΣg+1 transitions...
February 14, 2019: Journal of Chemical Physics
Zhuang Liu, Wei Luo, Chuanxi Duan
The rovibrational spectrum of the Ar-NO open-shell complex has been measured in the 5.3 µm region using distributed feed-back quantum lasers to probe the direct absorption in a slit-jet supersonic expansion. Five P-subbands, namely, P' ←P″ :1/2←3/2,1/2←1/2,3/2←1/2,5/2←3/2, and 7/2←5/2, are observed, with J up to 15.5. The hyperfine structure due to the nuclei spin of 14 N (I = 1) can be partially resolved in the P' ←P″ :1/2←3/2,1/2←1/2, and 3/2←1/2 subbands. The fine structure of the observed spectrum is analyzed using a modified semi-rigid rotor Hamiltonian [W...
February 14, 2019: Journal of Chemical Physics
Tim Lenzen, Uwe Manthe
An approach to systematically construct vibronically and spin-orbit coupled diabatic potential energy surfaces (PESs) for X(P) + CH4 → HX + CH3 reactions is proposed. Permutational symmetry and permutational invariants of the S4 group and its S3 and S2 × S2 subgroups are used to construct a diabatic model which properly describes the reaction starting from reactants to products. As a first example, the approach is applied to the construction of diabatic potentials for the F(2 P) + CH4 → HF + CH3 reaction...
February 14, 2019: Journal of Chemical Physics
Alexander M Berezhkovskii, Leonardo Dagdug, Sergey M Bezrukov
We study trapping of particles diffusing in a spherical cavity with an absorbing wall containing small static spherical absorbers localized in a spherical region in the center of the cavity. The focus is on the competition between the absorbers and the cavity wall for diffusing particles. Assuming that the absorbers and, initially, the particles are uniformly distributed in the central region, we derive an expression for the particle trapping probability by the cavity wall. The expression gives this probability as a function of two dimensionless parameters: the transparency parameter, characterizing the efficiency of the particle trapping by the absorbers, and the ratio of the absorber-containing region radius to that of the cavity...
February 14, 2019: Journal of Chemical Physics
Nadeepa Jayasundara, Roy B Anunciado, Emma Burgess, Seth Ashman, Lutz Hüwel
We report on calculations-using the LEVEL and BCONT programs by Le Roy, the latter of which is a version modified by B. McGeehan-of the dependence of the radiative lifetime of the Na2 sodium dimer 41 Σg + shelf-state on the initial vibrational and rotational level for corresponding quantum numbers of 0 ≤ v ≤ 75 and 0 ≤ J ≤ 90, respectively. We also present experimental lifetime values for 43 < v < 64, averaged over J = 19 and 21, obtained by a delayed pump-probe method using a previously described molecular beam and time-of-flight apparatus...
February 14, 2019: Journal of Chemical Physics
Si-Fan Liu, Bin Lin, Yu-Fei Xi, Le Zhou, Li-Li Lou, Xiao-Xiao Huang, Xiao-Bo Wang, Shao-Jiang Song
Correction for 'Bioactive spiropyrrolizidine oxindole alkaloid enantiomers from Isatis indigotica fortune' by Si-Fan Liu et al., Org. Biomol. Chem., 2018, 16, 9430-9439.
February 15, 2019: Organic & Biomolecular Chemistry
J Hernández-Rojas, F Calvo
The aggregation and physical growth of polycyclic aromatic hydrocarbon (PAH) molecules was simulated using a coarse-grained (CG) approach based on the Paramonov-Yaliraki (PY) potential and a stochastic Monte Carlo framework, following earlier efforts in which the structure [Phys. Chem. Chem. Phys., 2016, 18, 13736] and equilibrium thermodynamics [Phys. Chem. Chem. Phys., 2017, 19, 1884] were investigated and critically compared to the predictions of all-atom models. Homomolecular and heteromolecular assemblies of pyrene, coronene, and circumcoronene were considered at various temperatures and compositions, and the distributions of aggregation products were characterized...
February 15, 2019: Physical Chemistry Chemical Physics: PCCP
Yuling Hu, Shigong Wang, Xu Yang, Yanzhen Kang, Guicai Ning, Hui Du
The meteorological causes of winter droughts over Southwest China (SWC) have been widely investigated in recent years; however, little information is available on the impact of these droughts on air pollution. This study (1) characterized and quantified the impact of winter droughts on air pollution over SWC and (2) investigated the atmospheric teleconnections associated with the winter droughts in this region using air pollution monitoring data, routinely observed meteorological data, and National Centers for Environmental Prediction/National Center for Atmospheric Research and ERA-Interim reanalysis data...
January 28, 2019: Science of the Total Environment
Han Zhang, Wenjuan Jiang, Payal Chatterjee, Yun Luo
Reversible covalent inhibitors have drawn increasing attention in drug design, as they are likely more potent than noncovalent inhibitors and less toxic than covalent inhibitors. Despite those advantages, the computational prediction of reversible covalent binding presents a formidable challenge because the binding process consists of multiple steps and quantum mechanics (QM) level calculation is needed to estimate the covalent binding free energy. It has been shown that the dissociation rates and the equilibrium dissociation constants vary significantly even with similar warheads, due to noncovalent interactions...
February 14, 2019: Journal of Chemical Information and Modeling
Patrick Commins, Durga Prasad Karothu, Pance Naumov
The mention of the word 'crystal' invokes images of minerals, gems and rocks, all of which are inevitably solid, hard and durable entities with well-defined smooth faces and straight edges. With the discovery, in the first half of the 20th century that many molecular crystals are soft and can be deformed similarly to rubber or plastic (L. A. K. Staveley, Annu. Rev. Phys. Chem. 1962, 13, 351-368), this perception is evolving, and both the common apprehension and formal definition of what a crystal is may require reinterpretation in view of their extraordinary mechanical compliance...
February 14, 2019: Angewandte Chemie
Daniel Oliver, Monika Michaelis, Hendrik Heinz, Victor V Volkov, Carole C Perry
Polypeptide based biosilica composites show promise as next generation multi-functional nano-platforms for diagnostics and bio-catalytic applications. Following the identification of a strong silica binder (LDHSLHS) by phage display, we conduct structural analysis of the polypeptide at the interface with amorphous silica nanoparticles in an aqueous environment. Our approach relies on modelling infrared and Raman spectral responses using predictions of molecular dynamics simulations and quantum studies of the normal modes for several potential structures...
February 12, 2019: Physical Chemistry Chemical Physics: PCCP
Ruojing Peng, Andreas V Copan, Alexander Yu Sokolov
We present a new approach for simulating X-ray absorption spectra based on linear-response density cumulant theory (LR-DCT) [Copan, A. V.; Sokolov, A. Yu. J. Chem. Theory Comput., 2018, 14, 4097 - 4108]. Our new method combines the LR-ODC-12 formulation of LR-DCT with core-valence separation approximation (CVS) that allows to efficiently access high-energy core-excited states. We describe our computer implementation of the CVS-approximated LR-ODC-12 method (CVS-ODC-12) and benchmark its performance by comparing simulated X-ray absorption spectra to those obtained from experiment for several small molecules...
February 11, 2019: Journal of Physical Chemistry. A
(no author information available yet)
No abstract text is available yet for this article.
February 18, 2019: Angewandte Chemie
Katlyn A Fleming, Katie T Freeman, Mike D Powers, Radleigh G Santos, Ginamarie Debevec, Marc A Giulianotti, Richard A Houghten, Skye R Doering, Clemencia Pinilla, Carrie Haskell-Luevano
The centrally expressed melanocortin-3 and melanocortin-4 receptors (MC3R, MC4R) are established targets to treat diseases of positive and negative energy homeostasis. We previously reported (J. Med. Chem. 60:4342 2017) mixture-based positional scanning approaches to identify dual MC3R agonist and MC4R antagonist tetrapeptides. Herein, 46 tetrapeptides were chosen for MC3R agonist screening selectivity profiles, synthesized, and pharmacologically characterized at the mouse melanocortin-1, -3, -4, and -5 receptors...
February 11, 2019: Journal of Medicinal Chemistry
Elias Giannakis, Jonilda Kushta, Despina Giannadaki, George K Georgiou, Adriana Bruggeman, Jos Lelieveld
Agricultural emissions strongly contribute to fine particulate matter pollution (PM2.5) and associated effects on human health. Environmentally-extended input-output models and a regional atmospheric chemistry model (WRF-Chem) were combined to conduct an economy-wide assessment of air pollution and pre-mature mortality in the European Union (EU), associated with a 20% increase in the final demand for the output of the agricultural sector. Model results revealed significant differences in air pollution originating from agricultural growth across the 28 EU countries (EU-28)...
January 31, 2019: Science of the Total Environment
Timur Aslyamov, Vera Pletneva, Aleksey Khlyupin
Adsorption properties of chain fluids are of interest from both fundamental and industrial points of view. Density Functional Theory (DFT) based models are among the most appropriate techniques allowing to describe surface phenomena. At the same time, Statistical Associating Fluid Theory (SAFT) successfully describes bulk pressure-volume-temperature properties of chain-fluids. In this study, we have developed a novel version of the SAFT-DFT approach entitled Random Surface (RS)-SAFT which is capable of describing adsorption of short hydrocarbons on geometrically rough surfaces...
February 7, 2019: Journal of Chemical Physics
Killian Hull, Rebekah M Soliday, Isaiah Sumner, Paul L Raston
No abstract text is available yet for this article.
February 7, 2019: Journal of Chemical Physics
S Orioli, A Ianeselli, G Spagnolli, P Faccioli
No abstract text is available yet for this article.
February 7, 2019: Journal of Chemical Physics
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