Download or read book The Rotational Spectra and Analyses of Astrochemically Relevant Nitriles written by Pristine Matisha Dorman and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotational spectroscopy is a highly precise, analytical method utilized to identify molecular components of the interstellar medium (ISM). Radioastronomers rely on a molecule's pure laboratory rotational spectrum to probe various regions of the ISM for those unique transition frequencies. Each molecular isomer, conformer, isotopologue, and vibrational state has its own distinct rotational spectrum; and, in some cases, those detections can illuminate further extraterrestrial features, like environmental temperature. Rotational spectroscopy can be used to elucidate fundamental properties, such as an equilibrium structure, energy between vibrational states, and quantum state mixing interactions. Our group is keenly interested in the interstellar routes of formation/degradation for biologically fundamental heteroaromatics, such as pyridine. This thesis will focus on the millimeter-wave rotational spectra of astrochemically relevant nitriles and will mostly cover the efforts to determine accurate spectroscopic constants for vibrational states with Coriolis coupling. A comparison of the computationally predicted and experimental values are made to establish the meaningfulness of the determined constants and necessity of utilizing the appropriate rotational Hamiltonian.
Download or read book Synthesis of Astrochemically Relevant Small Molecules for Rotational Spectroscopy written by Samuel Kougias (Ph.D.) and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over 250 molecular species have been detected in the interstellar medium (ISM) via radioastronomy through the observation and assignment of rotational spectra. While relevant to the understanding of the chemical processes of the ISM, the presence of organic molecules in this environment has relevance to astrobiology regarding the origins of organic components critical for life on Earth. The McMahon/Woods group seeks to further develop the library of known celestial molecules by the synthesis and analysis of species theorized to be part of astrochemical systems. Our group has synthesized seven isomeric organic nitriles hypothesized to be present in the ISM and the atmosphere of Saturn's largest moon, Titan. Additionally, these nitriles are isomers of the aromatic heterocycle, pyridine, which has yet to be identified in the ISM. Synthetic methodology for the production and isolation of samples is presented. The isolation of pure samples of these reactive nitriles enables measurement of their laboratory rotational spectra, which are the critical data needed to search for these species in the cosmos via radioastronomy. Impact and importance of the highlighted species to the field of molecular spectroscopy and radioastronomy will be discussed
Download or read book Synthesis of Astrochemically Relevant Small Molecules for Rotational Spectroscopy written by Samuel Kougias (Ph.D.) and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over 250 molecular species have been detected in the interstellar medium (ISM) via radioastronomy through the observation and assignment of rotational spectra. While relevant to the understanding of the chemical processes of the ISM, the presence of organic molecules in this environment has relevance to astrobiology regarding the origins of organic components critical for life on Earth. The McMahon/Woods group seeks to further develop the library of known celestial molecules by the synthesis and analysis of species theorized to be part of astrochemical systems. Our group has synthesized seven isomeric organic nitriles hypothesized to be present in the ISM and the atmosphere of Saturn's largest moon, Titan. Additionally, these nitriles are isomers of the aromatic heterocycle, pyridine, which has yet to be identified in the ISM. Synthetic methodology for the production and isolation of samples is presented. The isolation of pure samples of these reactive nitriles enables measurement of their laboratory rotational spectra, which are the critical data needed to search for these species in the cosmos via radioastronomy. Impact and importance of the highlighted species to the field of molecular spectroscopy and radioastronomy will be discussed
Download or read book Rotational and Structural Analyses of Astrochemically Relevant Molecules written by Houston Hartwell Smith Ph.D. and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotational spectroscopy is an extremely powerful technique that allows for identification of molecules in different gaseous environments given their rotational spectrum has been measured, assigned, and least-squares fit to a proper Hamiltonian. Rotational spectroscopy is unique in that structural isomers, conformers, isotopologues, and vibrational states of a molecule all have a different rotational spectrum enabling their positive identification in a gas sample. Given the specificity of the technique and ubiquity of radio frequencies in the interstellar medium (ISM), the majority of the near 300 molecules detected in the ISM have come from radioastronomy. This thesis comprises the spectral assignment of five molecules with a unifying theme of providing new or updated spectroscopic constants for the search of these molecules in the ISM. Additionally, several molecules (1-cyanocyclobutene, 2-cyanopyrimidine, and cyanopyrazine) have their two lowest-energy vibrationally excited states Coriolis coupled to each other. This thesis uses a two-state, Coriolis coupled Hamiltonian to adequately address the measured rotational spectra, which are greatly affected by this coupling, and this results in an extremely precise determination of the energy separation between the vibrationally excited states. Two other molecules (ketene and methacrylonitrile) utilized the spectroscopic constants of different isotopologues along with high-level theoretical corrections to achieve highly precise and accurate semi-experimental equilibrium structures (reSE) with general precision to the ten-thousandth of an Angstrom and hundredths of a degree for bond distances and angles, respectively.
Download or read book The Study of Nitrogen containing Molecules of Astrochemical Importance Using Rotational Spectroscopy and Computational Chemistry written by Maria Zdanovskaia and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proper analysis of rotational spectra can provide insight into a variety of molecular properties, such as its structure, energy separations between vibrational states, and quantum-mechanical phenomena, such as coupling, to a high degree of accuracy and precision. Data acquired from the analysis can be used as benchmarks for computational chemistry, as well as in the experimental determination of related molecular properties. At the same time, high-level calculations can be used to support the experimental analysis. Additionally, most extraterrestrial molecular identifications are achieved using radioastronomy and require precise laboratory rotational spectroscopy measurements. The work presented in this dissertation details the gas-phase rotational spectral analysis of several molecules containing nitrogen (e.g., 1,2,3-triazole, benzonitrile, phenyl isocyanide, cyanobutadiene) and two nitrogen-less molecules. Some of these species' rotational spectra are studied for the first time and all works provide improved data for use with observational extraterrestrial data. Molecular properties gleaned include highly accurate and precise semi-experimental equilibrium structures, structural comparisons between benzonitrile and phenyl isocyanide, highly precise energy separations between vibrational states, vibrational-state term energies, coupling terms, and anharmonicity constants.
Download or read book Microwave and Millimeter Wave Astrochemistry written by Gilles Rapotchombo Adande and published by . This book was released on 2013 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Progress in our understanding of the chemical composition of the interstellar medium leans both on laboratory analyses of high resolution rotational spectra from molecules that may be present in these regions, and on radio astronomical observations of molecular tracers to constrain astrochemical models. Due to the thermodynamic conditions in outer space, some molecules likely to be found in interstellar regions in relevant abundances are open shell radicals. In a series of laboratory studies, the pure rotational spectra of the transition metal containing radicals sulfur species ScS, YS, VS and ZnSH were obtained for the first time. In addition to accurate and precise rest frequencies for these species, bonding characteristics were determined from fine and hyperfine molecular parameters. It was found that these sulfides have a higher degree of covalent bonding than their mostly ionic oxide counterparts. Isomers and isotope ratios are excellent diagnostic tools for a variety of astrochemical models. From radio observations of isotopes of nitrile species, the galactic gradient of 14N/15N was accurately established. A further study of this ratio in carbon rich asymptotic giant branch stars provided observational evidence for an unknown process in J type carbon stars, and highlighted the need to update stellar nucleosynthesis models. Proper radiative transfer modeling of the emission spectra of interstellar molecules can yield a wealth of information about the abundance and distribution of these species within the observed sources. To model the asymmetric emission of SO and SO2 in oxygen-rich supergiants, an in-house code was developed, and successfully applied to gain insight into circumstellar sulfur chemistry of VY Canis Majoris. It was concluded that current astrochemistry kinetic models, based on spherical symmetry assumptions, need to be revisited.
Download or read book Computational and Spectroscopic Investigations of Species of Astrochemical Relevance written by and published by . This book was released on 2012 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work focuses on several research projects that apply computational or spectroscopic techniques to study molecules of astrochemical relevance. Chapters 1 and 2 discuss computational projects relevant to carbon condensation and fullerene formation as proposed by the coalescence and annealing model. We find that alkynyl substitution of cyclobutadiene provides stabilization of the antiaromatic species which provides support of the proposed poly-alkynl cyclobutadiene intermediate. Further theoretical investigation reveals that the cyclization of the poly-alkynyl cyclobutadiene to form a para diradical via a Bergman cyclization may not be a viable step in fullerene formation and does not lead to the necessary 6-membered rings. This work calls into question the coalescence and annealing model of carbon condensation and fullerene formation. Chapter 3 details a computational investigation of the decomposition of carbonyl diazide into diazirinone. This builds upon previous work refuting the original reports of diazirinone generation and our subsequent work synthesizing carbonyl diazide as a potential precursor. While incomplete, this work shows how the conformers of carbonyl diazide can interconvert and, by loss of nitrogen, can form 3nitreno-carbonylazide or azidoisocyanate. Higher-level, multi-reference calculations, such as SF-EOM-CCSD are likely needed to obtain a more definitive decomposition pathway that leads to diazirinone. Chapters 4 and 5 describe the type of laboratory rotational spectroscopy typically used by radio astronomers to detect molecules in the interstellar medium. Chapter 4 describes the reconstruction and programming of the millimeter-wave spectrometer used to make these measurements. This instrument allowed us to complete an investigation of the rotational spectrum of pyridazine. We have observed several thousand transitions of pyridazine, its isotopomers, and its vibrationally-excited states. This work provides the spectroscopic data that are needed to search for this important 6-membered aromatic heterocycles in the interstellar medium by radioastronomy. Chapter 6 describes an authentic use of computational chemistry to support the experiments completed in an undergraduate organic chemistry laboratory course. As a result of the curriculum redevelopment project, undergraduates are using WebMO and Gaussian to calculate conformers, transition states, reaction intermediates, molecular orbitals, and natural bond orbitals.
Download or read book RNA World Hypothesis and the Origin of Life Astrochemistry Perspective written by Ashraf - Ali and published by Frontiers Media SA. This book was released on 2022-09-26 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopy from Space written by Jean Demaison and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many satellites have recently been launched or are in preparation, which operate in the microwave to IR ranges, the main objective being to observe the earth's atmosphere or interstellar clouds. Analysis of the data they supply requires extensive laboratory work because we still only have sufficiently accurate data (line positions, intensities, and profiles) for only a few species. Furthermore, the observer community is making increasing calls for laboratory data, as new development open up new observational possibilities (such as submillimeter observation). Research on these subjects involves many different areas of specialisation in fields of research that generate a wealth of data. In Spectroscopy from Space the people responsible for field observations explain which results they are expecting from their measurements and how laboratory people can help them to analyse their satellite data. Laboratory spectroscopists explain why what they can do now, and what kinds of experiment and theoretical development that might undertake to meet the needs of the remote sensing community. The problems of distributing reliable laboratory data in a timely way are also addressed.
Download or read book Origins of Life The Primal Self Organization written by Richard Egel and published by Springer Science & Business Media. This book was released on 2011-08-31 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: If theoretical physicists can seriously entertain canonical “standard models” even for the big-bang generation of the entire universe, why cannot life scientists reach a consensus on how life has emerged and settled on this planet? Scientists are hindered by conceptual gaps between bottom-up inferences (from early Earth geological conditions) and top-down extrapolations (from modern life forms to common ancestral states). This book challenges several widely held assumptions and argues for alternative approaches instead. Primal syntheses (literally or figuratively speaking) are called for in at least five major areas. (1) The first RNA-like molecules may have been selected by solar light as being exceptionally photostable. (2) Photosynthetically active minerals and reduced phosphorus compounds could have efficiently coupled the persistent natural energy flows to the primordial metabolism. (3) Stochastic, uncoded peptides may have kick-started an ever-tightening co-evolution of proteins and nucleic acids. (4) The living fossils from the primeval RNA World thrive within modern cells. (5) From the inherently complex protocellular associations preceding the consolidation of integral genomes, eukaryotic cell organization may have evolved more naturally than simple prokaryote-like life forms. – If this book can motivate dedicated researchers to further explore the alternative mechanisms presented, it will have served its purpose well.
Download or read book Laboratory Astrochemistry written by Stephan Schlemmer and published by John Wiley & Sons. This book was released on 2015-04-27 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by leading scientists in the field and intended for a broader readership, this is an ideal starting point for an overview of current research and developments. As such, the book covers a broad spectrum of laboratory astrophysics and chemistry, describing recent advances in experiments, as well as theoretical work, including fundamental physics and modeling chemical networks. For researchers as well as students and newcomers to the field.
Download or read book Laboratory Astrophysics written by Guillermo M. Muñoz Caro and published by Springer. This book was released on 2018-10-11 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the most recent, relevant, comprehensive and significant aspects in the well-established multidisciplinary field Laboratory Astrophysics. It focuses on astrophysical environments, which include asteroids, comets, the interstellar medium, and circumstellar and circumplanetary regions. Its scope lies between physics and chemistry, since it explores physical properties of the gas, ice, and dust present in those systems, as well as chemical reactions occurring in the gas phase, the bare dust surface, or in the ice bulk and its surface. Each chapter provides the necessary mathematical background to understand the subject, followed by a case study of the corresponding system. The book provides adequate material to help interpret the observations, or the computer models of astrophysical environments. It introduces and describes the use of spectroscopic tools for laboratory astrophysics. This book is mainly addressed to PhD graduates working in this field or observers and modelers searching for information on ice and dust processes.
Download or read book Astrochemistry and Astrobiology written by Ian W. M. Smith and published by Springer Science & Business Media. This book was released on 2012-10-28 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrochemistry and Astrobiology is the debut volume in the new series Physical Chemistry in Action. Aimed at both the novice and experienced researcher, this volume outlines the physico-chemical principles which underpin our attempts to understand astrochemistry and predict astrobiology. An introductory chapter includes fundamental aspects of physical chemistry required for understanding the field. Eight further chapters address specific topics, encompassing basic theory and models, up-to-date research and an outlook on future work. The last chapter examines each of the topics again but addressed from a different angle. Written and edited by international experts, this text is accessible for those entering the field of astrochemistry and astrobiology, while it still remains interesting for more experienced researchers.
Download or read book Spectroscopy and Modeling of Biomolecular Building Blocks written by Jean-Pierre Schermann and published by Elsevier. This book was released on 2007-10-16 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectroscopy and Modeling of Biomolecular Building Blocks presents an overview of recent advances in the intertwining of the following research fields: photon and electron spectroscopy, quantum chemistry, modelling and mass-spectrometry. The coupling of these disciplines offers a new point of view to the understanding of isolated elementary building blocks of biomolecules and their assemblies. It allows the unambiguous separation between intrinsic properties of biomolecular systems and those induced by the presence of their environment. The first chapters provide background in modelling (I), frequency-resolved spectroscopy using microwave, infrared and UV photons, time-resolved spectroscopy in the femtosecond domain and energy-resolved electron spectroscopy (II) and production of gas-phase neutral and ionic biomolecular species, mass-spectrometry, ion mobility and BIRD techniques (III). Chapter IV is devoted to case studies of gas-phase experimental investigations coupled to quantum or classical calculations. The topics are structural studies of nucleobases and oligonucleotides, peptides and proteins, sugars; neuromolecules; non-covalent complexes; chiral systems, interactions of low-energy electrons with biomolecules in the radiation chemistry context and very large gas-phase biomolecular systems. The fifth chapter concerns the link between gas-phase and liquid-phase. Different treatments of solvation are illustrated through examples pointing out the influence of progressive addition of water molecules upon properties of nucleobases, peptides, sugars and neuromolecules. Offer a new perspective to the understanding of isolated elementary building blocks of bio molecules Includes case studies of experimental investigations coupled to quantum or classical calculations
Download or read book Vibrational Spectra and Structure written by James R. Durig and published by . This book was released on 1972-01-01 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structure of Small Molecules and Ions written by Ron Naaman and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: The workshop on "The structure of small molecules and ions" was held at the Neve-Han guest house, near Jerusalem, Israel on December 13 to 18 in mem ory of the late Professor Itzhak Plesser. Professor Plesser played a central role in the research done both at the Weizmann Institute and at Argonne National Laboratories on the "Coulomb explosion" method. His friends honored his memory by organizing a meeting in which subjects related to Plesser's interests would be discussed. Just a week be fore the conference started we were struck by another tragedy -the death of our graduate student Ms. Hana Kovner, who participated in many of the Coulomb explosion experiments at the Weizmann Institute. We would like to dedicate these proceedings to her memory as well. The goal of the workshop was to bring together chemists and physicists working on different aspects of the structural problems of small molecular en tities. The time seemed appropriate for discussing experimental and theoretical concepts, since in recent years new methods have been introduced, and a large amount of information has been accumulated on systems not studied before, like unstable molecules, ions, van der Waals molecules and clusters. The program of the workshop reflects, we believe, these new developments. The meeting was characterized by intensive discussions in which the weak nesses and strengths of new and of well established concepts were revealed. We hope that it measured up to the high standards Itzhak Plesser maintained all through his scientific life.
Download or read book The Search for Life s Origins written by National Research Council and published by National Academies Press. This book was released on 1990-02-01 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of planetary biology and chemical evolution draws together experts in astronomy, paleobiology, biochemistry, and space science who work together to understand the evolution of living systems. This field has made exciting discoveries that shed light on how organic compounds came together to form self-replicating molecules-the origin of life. This volume updates that progress and offers recommendations on research programs-including an ambitious effort centered on Mars-to advance the field over the next 10 to 15 years. The book presents a wide range of data and research results on these and other issues: The biogenic elements and their interaction in the interstellar clouds and in solar nebulae. Early planetary environments and the conditions that lead to the origin of life. The evolution of cellular and multicellular life. The search for life outside the solar system. This volume will become required reading for anyone involved in the search for life's beginnings-including exobiologists, geoscientists, planetary scientists, and U.S. space and science policymakers.
