Download or read book Rotational Spectra of Elusive Molecules in the Laboratory and in Space written by Silvia Spezzano and published by . This book was released on 2014 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rotational Spectroscopy of Diatomic Molecules written by John M. Brown and published by Cambridge University Press. This book was released on 2003-04-10 with total page 1074 pages. Available in PDF, EPUB and Kindle. Book excerpt: The definitive text on the rotational spectroscopy of diatomic molecules.

Download or read book Vibrational rotational Spectroscopy And Molecular Dynamics written by Dusan Papousek and published by World Scientific. This book was released on 1997-10-31 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book reviews the results of vibration-rotational spectroscopy of molecules obtained recently by combining modern computational methods of quantum chemistry with the new techniques of high-resolution rotational and vibration-rotational spectroscopy. It shows for example that the tunneling vibration-rotational spectroscopy of the van der Waals complexes provides a new look at intermolecular forces while the high precision and sensitivity of the submillimeter-wave and Fourier transform microwave spectroscopy make it possible to study complex rotational spectra of molecules in excited vibrational states. New results of high level ab initio quantum chemical computations of vibrational and rotational energy levels and dipole moment functions of unusual molecules will be discussed together with the recent discovery of clustering of energy levels in asymmetric tops. Group theoretical analysis of floppy molecules, especially the tunneling effects in nonrigid molecules, will also be discussed.

Download or read book Molecular Vibrational rotational Spectra written by Dušan Papoušek and published by Elsevier Science & Technology. This book was released on 1982 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rotational and Vibrational Spectroscopy and Structure Determination of Organic Molecules of Astrochemical Relevance written by Vanessa Linn Orr and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rotational spectrum of a molecule is directly linked to its structure, and the laboratory rotational spectrum provides information for a search for the molecule in extraterrestrial environments through radio astronomy. This thesis presents the analysis of the rotational spectroscopy of three organic molecules that are of interest in astrochemistry and structurally. The rotational spectrum of diketene (H[2]C=CCH[2]OC=O), the dimer of ketene, was analyzed between 240 and 360 GHz. Rotational spectroscopic constants for the ground state and eight higher energy vibrational states were determined with least-squares fits to single-state, sextic distorted-rotor Hamiltonian models. The new X-ray crystal structure and high-level calculations resolve discrepancies between earlier experimental and computational data in the previous literature. 4-Cyano-1,2-butadiene (H[2]C=C=CH-CH[2]CN), a butadiene isomer of the heterocycle pyridine, is a molecule of astrochemical interest. The rotational spectrum was collected from 130 to 375 GHz and has allowed for the determination of the rotational spectroscopic constants for the ground state of the syn conformer. The ground state of the anti conformer ground state exhibits evidence of coupling with the low-energy vibrational state corresponding to the internal rotation of the -CH[2]CN group, [nu]27. The ground state, v = 1, 2, 3, 4 of [nu]27, and [nu]26 of the anti conformer have been incompletely treated with single-state, distorted-rotor Hamiltonian models. The third molecule investigated is the heterocycle thiophene (C[4]H[4]S). The semi-experimental equilibrium structure (r[e][SE]) of thiophene has been determined from 24 isotopologues whose experimental rotational constants are computationally corrected for vibration-rotation interactions and electron mass. This r[e][SE] structure is compared to the best possible theoretical estimate. Finally, the spectroscopic constants for the vibrational states of thiophene between 0 and 1163 cm[−1] are presented. For many of these vibrational states, we combine our mm-wave transitions with high-resolution infrared transitions available from previous literature. The appendices contain information about our collaboration with the Canadian Light Source and updates to our mm-wave spectrometer.

Download or read book Rotational Spectroscopy of Diatomic Molecules written by John M. Brown and published by . This book was released on 2003 with total page 1013 pages. Available in PDF, EPUB and Kindle. Book excerpt: The definitive text on the rotational spectroscopy of diatomic molecules.

Download or read book Reviews in astronomy and space sciences written by Christopher H. K. Chen and published by Frontiers Media SA. This book was released on 2024-05-24 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Astrochemistry of Cosmic Phenomena written by P.D. Singh and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: The IAU symposium No. 150 "Astrochemistry of Cosmic Phenomena" was held at the beautiful and scenic town of Campos do Jordao, Sao Paulo, Brazil from August 5 to 9, 1991, and was attended by 111 registered participants with 17 accompanied guests from 19 countries. The symposium had a wide ranging discussion of the chemistry of astronomical environments with an emphasis on the description of molecular processes that critically influence the nature and evolution of astronomical objects and the identification of specific observations that directly address significant astronomical questions. The subject areas of the symposium included atomic and molecular processes at low and high temperatures and photon interactions, the chemical structure of molecular clouds in the Milky Way and in external galaxies, the chemistry of outflows and their interactions with the interstellar medium, the chemical connections between the interstellar medium and the solar system and pregalactic chemistry. The scientific programme comprised of review talks and con tributed papers, with a general introduction by Professor A. Dalgarno and a final overview of the whole symposium by Professor D. A. Williams. Financial supports from the Sao Paulo State Foundation Support (FAPESP), Brazilian National Research Council(CNPq), Finance Company of Studies and Projects (FINEP), Institute of Astronomy and Geophysics of University of Sao Paulo (IAG-USP) and Inter national Astronomical Union (IAU) are greatfully acknowledged. I am greatly indebted to Professor A.

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 Rotational Spectroscopy of Nitrogen and Chlorine Containing Species to Guide Interstellar and Planetary Observations written by Hayley Ann Bunn and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The following dissertation focuses on the collection and analysis of laboratory rotational spectra of molecules predicted to exist in the interstellar medium and/or planetary atmospheres. This dissertation is split into two main sections based on the terrestrial stability of target molecules. The first part investigates the use of O(1D) insertion reactions for the formation of terrestrially unstable prebiotic molecules, with a particular focus on aminomethanol (NH2CH2OH). The insertion of O(1D) into methylamine is one proposed pathway to form aminomethanol. However, this formation pathway is highly exothermic and results in a complex mixture of reaction products, complicating spectral assignment. A systematic experimental study of these reaction pathways is presented by using millimeter/ submillimeter spectroscopy in the frequency and time domain, and a kinetic box model. An examination of the implications of these results is then presented to assist in future studies aimed at forming and detecting aminomethanol. The second part of this dissertation involves the collection and analysis of the rotational spectra of 2-chloroethanol and 1,2,4-triazole, both of which are terrestrially stable but have complex spectral patterns. The spectrum of each molecule is complicated by nuclear quadrupole coupling in addition to multiple vibrational states, perturbed by Coriolis coupling. The spectra are collected in the millimeter/submillimeter regime providing spectral frequencies directly comparable to radio telescopes. This information, along with the determined rotationalconstants and high order centrifugal distortion constants, will allow for the astronomical search of each species. A complete reSE structure of 1H-1,2,4-triazole is also reported following the analysis of an additional 26 isotopologues.

Download or read book Rotational Structure in the Spectra of Diatomic Molecules written by István Kovács and published by . This book was released on 1969 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 Submillimeter Laboratory Investigations written by Eric Herbst and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Our group was the first to extend studies of the rotational spectra of small and fundamental gas-phase molecules from the microwave into first the millimeter-wave and subsequently the submillimeter-wave region of the spectrum(King & Gordy 1953;Helmingeret al. 1970,1983).A bibliography of the many molecules studied in the laboratory, consisting of over400 papers, is available upon request. The results presented in these papers provide the basis for the identification of a significant fraction of the interstellar spectral lines. For interstellar molecules previously detected at lower frequencies, our submillimeter-wave spectra provide the opportunity for additional study of these species under warmer conditions. For the duration of this proposal and previously, we have concentrated on those molecules with the Largest number of interstellar spectral lines. These species are so-called internal rotors, in which one portion of the molecule(normally a methyl (CH3) group) undergoes a hindered rotational motion with respect to the other portion of the molecule. The hindered rotational motion, known as torsion, leads to quantized states typically separated by 50-100 K and labeled with a quantum number vt= 0,1,2 ... For the three-fold case, each torsional state is also split into two substates-designated A and E. The existence of these extra states compared with normal molecules is of great use for probing warm regions with temperatures too low to excite normal vibrations but higher than the ambient interstellar medium. Strong interactions between torsional and rotational motion, however, make the spectra of some internal rotors quite complex and, for many years, it was very difficult if not impossible to analyze their spectra to microwave accuracy. Without such a detailed analysis, it is not possible to predict the frequencies of the many lines not measured in the laboratory with sufficient precision for use by radio astronomers, nor to determine intensities."--Page 2.

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 Frontiers and Advances in Molecular Spectroscopy written by Jaan Laane and published by Elsevier. This book was released on 2017-11-13 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt: Frontiers and Advances in Molecular Spectroscopy once again brings together the most eminent scientists from around the world to describe their work at the cutting-edge of molecular spectroscopy. Much of what we know about atoms, molecules and the nature of matter has been obtained using spectroscopy over the last one hundred years or so. Going far beyond the topics discussed in Jaan Laane’s earlier book on the subject, these chapters describe new methodologies and applications, instrumental developments and theory, which are taking spectroscopy into still new frontiers. The robust range of topics once again demonstrates the wide utility of spectroscopic techniques. New topics include ultrafast spectroscopy of the transition state, SERS/far-uv spectroscopy, femtosecond coherent anti-Stokes Raman spectroscopy, high-resolution laser induced fluorescence spectroscopy, Raman spectroscopy and biosensors, vibrational optical activity, ultrafast two-dimensional spectroscopy, biology with x-ray lasers, isomerization dynamics and hydrogen bonding, single molecule imaging, spectra of intermediates, matrix isolation spectroscopy and more. Covers spectroscopic investigations on the cutting edge of science Written and edited by leading experts in their respective fields Allows researchers to access a broad range of essential modern spectroscopy content from a single source rather than wading through hundreds of scattered journal articles