Despite several space mission and astronomical observation made from earth, the structure, color and mode of formation of Jupiter planet and other Jovian planet remain largely unknown. Understanding the atmosphere, haze and the colors of these planets, especially the great red spot (GRS) of Jupiter and its belts are still a big challenge for both experimenters and theorists. Jupiter’s colors range from blue to orange with some green regions. The most important chemical components that are responsible for the coloring of Jupiter and other Jovian planets are mainly CH4, NH4SH, H2O and NH3 [1-3]. Although an explanation for the color of Jupiter have been suggested to involve these species or other related molecules arise from the interaction between these species in gas phase. In this report, we present our studies on the color of Jupiter. We have examined the electronic structure, stability infra-red and UV-Vis spectroscopy of NH4SH and other related molecules in crystalline and gas phase using Density Functional Theory (DFT) and ab-initio methods, are we report new insights from the spectroscopy NH4SH in explaining the different color regions of Jupiter. References: 1.Roman, M.T., Banfield, D., Gierasch, P.J., Icarus, 225, 93 (2013). 2.Atreya,S.K et al., Planet Space Sci., 47, 1243 (1999). 3.Weidenschilling, S.J., Lewis, J.S., Icarus 20, 465 (1973).

Recent studies indicate that nitrogen oxide species in the atmosphere, including N₂O₅ and ONONO₂, undergo a new class of S_N2-type substitution reactions when in contact with seawater and sea spray aerosols.P. J. Kelleher, F. S. Menges, J. W. DePalma, J. K. Denton, M. A. Johnson, G. H. Weddle, B. Hirshberg, R. B. Gerber, J. Phys. Chem. Lett. 8, 4710 (2017).^,R. B. Gerber, L. McCaslin, N. V. Karimova, Faraday Discuss. (Accepted).^,L. M. McCaslin, M. A. Johnson, R. B. Gerber, (In review)he reactions of atmospheric nitrogen oxides with seawater play many integral roles in regulating levels of O₃, OH, NO_x, and CH₄, thus directly affecting radiative forcing and global climate. However, the effect of the number of water molecules on the mechanisms for this new group of S_N2-type reactions of nitrogen oxides and the competition of these processes with hydrolysis have not yet been characterized. Here we present the mechanisms and timescales of S_N2-type substitution and hydrolysis reactions of N₂O₅ with seawater in the cluster series N₂O₅ + Cl⁻ + nH₂O (n=1-5). Previous studies of the cluster N₂O₅ + Cl⁻ + H₂O provide deep insights into the local behavior of these systems.^c The presented studies of this cluster with water molecules added one-by-one allows for a detailed understanding of the effects of a solvation shell as it is built, providing a connection between the behavior of these small clusters and atmospherically relevant systems. Vibrational spectroscopic signatures of key intermediates are discussed and compared to recent and ongoing experiments.^a

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P. J. Kelleher, F. S. Menges, J. W. DePalma, J. K. Denton, M. A. Johnson, G. H. Weddle, B. Hirshberg, R. B. Gerber, J. Phys. Chem. Lett. 8, 4710 (2017).\end R. B. Gerber, L. McCaslin, N. V. Karimova, Faraday Discuss. (Accepted). L. M. McCaslin, M. A. Johnson, R. B. Gerber, (In review)T

Condensed-phase systems represent a vast swath of chemical problems that are of biological and atmospheric interest. Force fields for simulations of these liquid phases need to be able to model intermolecular interactions accurately. Moreover, reliable potentials for spectroscopic calculations need to reproduce site energies and molecular properties, as well as predict fluctuations in molecular coupling appropriately. A local mode approach to the calculation of IR spectra of condensed phase systems of CH stretches will be taken. This is justified because solutions of only CH stretches tend to exhibit less correlated network behavior than solutions of mixed CH/XH (X=O,N) stretch solvents due to weaker intermolecular forces. In an effort to understand solvent effects in the condensed phase, previously developed model gas-phase Hamiltonians will be extended to describe liquid CH stretch systems. As a first step, benzene will be investigated due to its high degree of symmetry and availability of force fields that describe its intermolecular interactions. Benzene represents a technical challenge for vibrational spectroscopy due to the presence of a Fermi triad in its CH stretch IR spectrum. By incorporating these couplings into the model Hamiltonian, it will be possible to consider solvent effects on the IR spectrum of the noncovalently bound benzene dimer. Extension of the dimer model to the condensed phase will allow for discussion of other relevant spectra of benzene, especially its vibrational sum-frequency generation (VSFG) spectrum.

Water plays a very important role in surface science of electrochemical interfaces, closely associated with energy source, environment, our living, and life processes. However, it is very difficult to be observed from normal Raman spectra of water in electrochemical interfaces. Although the surface-enhanced Raman scattering effect can have million-fold Raman signal enhancement for molecules on adsorbed silver and gold electrodes of nanostructures, the surface-enhanced Raman spectrum of water is hard to be measured due to its very small Raman scattering cross section, weak adsorption ability, and very few surface molecular number relative to the bulk. Thus only electrochemical SERS spectra of water have been observed in electrode/electrolyte interfaces so far. Our present work focuses on the chemical enhancement from hydrogen bonding interaction, surface adsorption, halide ions, interfacial electric field effects on SERS signals of water adsorbed on silver electrodes, by combining the metallic cluster model and hybrid density functional theory (DFT-B3LYP) methods. The interfacial structures, binding interactions and the anion effect from different halides including chloride, bromide, and iodide ions have been analyzed and compared with experimental measurements in literatures. Then the excited states of halide ions modified active sites on roughened silver electrode have been discussed. Especially, our time-dependent DFT (TD-DFT) calculations predicted that halide ions can form low-lying excited states of surface complexes, like the photon-induced electron transfer states, and finally contribute to the chemical enhancement of SERS signals of water. Furthermore, we proposed that the halide effect on the relative SERS intensities of water is a good example for understanding the chemical enhancement of SERS active sites modified by halide ions in electrochemical systems.

Some reactions producing extremely hot nascent products-with vibrational quantum numbers at least as high as 30-nevertheless form relatively long-lived weakly-bound van der Waals (vdW) complexes with bath gas molecules that are observable via microwave rotational spectroscopy. One example is SiO, formed in the reaction of various silanes with oxygen. M. C. McCarthy, S. A. Ndengué and R. Dawes, The rotational spectrum and potential energy surface of the Ar-SiO complex, J. Chem. Phys. 149, 134308 (2018).he reason for the long lifetimes of the complexes, despite having internal energies that greatly exceed the vdW well depth, is the very weak coupling between the intra- and intermolecular modes. Theoretical calculations of such unbound resonance states can be much more challenging than ordinary bound state calculations since approaches to deal with the dissociating wavefunction (such as complex absorbing potentials) are less straightforward and much more time consuming. We have demonstrated that a simplified approach of making a series of vibrationally effective PESs for the intermolecular coordinates (one for each reaction product vibrational quantum number of interest) can produce vdW levels for the complex that are of spectroscopic accuracy. Here we will describe how our freely available PES fitting code called AUTOSURF E. Quintas-Sánchez and R. Dawes, AUTOSURF: A Freely Available Program to Construct Potential Energy Surfaces, J. Chem. Inf. Model. 59, 262-271 (2019). R. Dawes and E. Quintas-Sánchez, The Construction of Ab Initio-Based Potential Energy Surfaces, Reviews in Computational Chemistry, Volume 31, Chapter 5, pp. 199-263, John Wiley & Sons (2018). can be used to construct the necessary PESs using automation. The code is demonstrated here by presenting spectroscopic-quality potential energy surfaces for Ar-CS and Ar-SiS complexes.

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 M. C. McCarthy, S. A. Ndengué and R. Dawes, The rotational spectrum and potential energy surface of the Ar-SiO complex, J. Chem. Phys. 149, 134308 (2018).T  E. Quintas-Sánchez and R. Dawes, AUTOSURF: A Freely Available Program to Construct Potential Energy Surfaces, J. Chem. Inf. Model. 59, 262-271 (2019).

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Using a series of vibrationally effective PESs constructed using the automated AUTOSURF code, E. Quintas-Sánchez and R. Dawes, AUTOSURF: A Freely Available Program to Construct Potential Energy Surfaces, J. Chem. Inf. Model. 59, 262-271 (2019). R. Dawes and E. Quintas-Sánchez, The Construction of Ab Initio-Based Potential Energy Surfaces, Reviews in Computational Chemistry, Volume 31, Chapter 5, pp. 199-263, John Wiley & Sons (2018). rovibrational levels and predicted microwave transition frequencies of the SiS-Ar and CS-Ar complexes were computed variationally. A series of shifting rotational transition frequencies were computed as a function of the diatom vibrational quantum number. For each system, the predicted spectra are compared with experimental microwave measurements.

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Footnotes:

 E. Quintas-Sánchez and R. Dawes, AUTOSURF: A Freely Available Program to Construct Potential Energy Surfaces, J. Chem. Inf. Model. 59, 262-271 (2019).

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Proteins and peptides are of interest to many different research groups across all fields of chemistry and biology. Of special interest is understanding conformational changes within proteins that occur due to different amino acid substituents, especially those that differ by just a side chain. However, it is very difficult to completely analyze a protein’s full local environment due to spectral congestion from the different conformers of each protein. Thus, small peptides (N-chain, N=1-5) are used as model systems for both floppy and non-floppy chain systems to probe the effect of the R-group on the conformation population. Prior in the Garand group, conformations of protonated triglycine (Gly₃H⁺) have been found for the bare peptide as well as when the peptide has one water molecule clustered around it. Therefore, in order to investigate how varying the side chain affects the conformations of these chained peptides, protonated trialanine (Ala₃H⁺) is used due to the fact that the side chain here is changed from a hydrogen to a methyl group. Utilizing Cryogenic Ion Vibrational Spectroscopy (CIVS) and electronic structure calculations, highly resolved structural features of these systems will be elucidated. Conformer-specific IR-IR double resonance techniques will be used in to quantify the contribution of various conformers. This technique will allow the probing of how non-covalent interactions, with particular focus on intramolecular peptide H-bonding, change as a function of side chain. From these model systems, it will then be possible to extrapolate such characterization to larger peptides. Further on, through the use of microsolvation, it will be possible to determine the changes in conformation as a function of not only the side chain, but also through water-peptide H-bonding interactions.

Late transition metals are studied as model systems for single atom catalysis in the gas phase with infrared photodissociation spectroscopy. Clusters of M⁺(acetylene)_n (n = 1-8) are produced via laser vaporization of either cobalt, rhodium, or platinum rods in a supersonic expansion of argon containing acetylene. Infrared photodissociation spectroscopy of smaller clusters is accomplished with the aid of argon tagging. Larger clusters are studied through the elimination of one or more acetylene ligands. These spectra are assigned with the aid of B3LYP/Def2TZVP computations. The structure and size of the inner coordination sphere is discussed.

Because of the involvement of low-lying 3d levels in bonding and polarizability, calcium resembles an early transition metal. In a biological context, calcium has bonding flexibility, high availability, and is an essential component of many proteins. It is metered or gated by voltage or ligands through calcium channels, and is processed and remodeled in bone and shell structure. In the case of diatomics, ab-initio calculations and the interpretation of Rydberg spectra can be used to infer effective atomic charges, and dipole-dipole or dipole-quadrupole polarizability for the Ca cation, and charge and dipole-dipole polarizability for the ligand. Calculations with an external point-charge perturbation can provide additional types of molecular polarizability values. Calculations on calcium difluoride, CaF2, which, surprisingly, is non-linear, can provide the same type of information about the atomic constituents. We compare the metal and ligand effective atomic electric properties of the diatomic and triatomic, and compare to the values used for biological systems.