Download or read book Vibration rotational Spectroscopy and Molecular Dynamics written by Du?an Papou?ek and published by World Scientific. This book was released on 1997 with total page 578 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 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 Millimeter and Submillimeter Spectroscopy of Molecules of Atmospheric Importance written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-12-28 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: In our proposal we laid out work in three areas of relevance to atmospheric science: millimeter and submillimeter spectroscopy, variable temperature pressure broadening, and band and intensity measurements in the FIR. Below we will briefly discuss our progress during the second year of this project. In our millimeter and submillimeter (mm/submm) spectroscopic work, one of our goals has been to work towards the unification of the rotational (primarily obtained by mm/submm techniques) and rotational-vibrational (primarily obtained by infrared techniques) data sets in the context of theoretically well founded models which take advantage of the strengths of the data from each experimental technique. From the point of view of the development of the optimal data base for atmospheric observations, this is clearly a desirable goal. During the first year of this project we did an analysis of a weighted, mixed infrared and mm/submm data set of the n = 0, 1, and 2 torsional states of the ground vibrational state of HOOH. The purpose of this work is to provide a unified understanding of the spectrum, which is applicable in both the rotational and rotational - vibrational regimes. We have succeed in doing this in the context of a single weighted fit which accounts for both data sets to their respective experimental uncertainty (-0.1 and 10 MHz, respectively). Additionally, we have now done a similar analysis on the n = 0 torsional state of v(sub 3) and begun a similar analysis on v(sub 6). For several years we have been working on the mm/submm rotational spectra of the many excited vibrational states of HNO3, again with particular emphasis on the relationships between the mm/submm and infrared spectra. During the first year of this project we were able to use mm/submm spectroscopy to fully resolve the torsional splittings in 2 v(sub 9) and v(sub 5), establish a theoretically well founded quantitative relation between them, and show that both have their physical origin in the tor...
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 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 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 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 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 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 Molecular Vibrational rotational Spectra written by Dusan Papousek and published by . This book was released on 1982 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Millimeter wave Spectroscopic and Collisional Studies of Molecules and Molecular Ions written by John C. Pearson and published by . This book was released on 1995 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Relaxation Studies written by W. J. Orville-Thomas and published by . This book was released on 1972 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Vibrational rotational Spectra written by Dusan Papousek and published by . This book was released on 1982 with total page 323 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 Introduction to Spectroscopy written by Donald L. Pavia and published by . This book was released on 2015 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopy of Molecular Rotation in Gases and Liquids written by A. I. Burshtein and published by Cambridge University Press. This book was released on 1994-07-21 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the fundamental concepts and models which underpin the spectroscopic study of gases and liquids, first published in 1994.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1987 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt:
