Download or read book Aspects of Collision induced Absorption of Hydrogen and Deuterium written by Paul G. Gillard and published by . This book was released on 1983 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aspects of Collision induced Absorption of Hydrogen and Deuterium written by Paul G. Gillard and published by . This book was released on 1983 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Collision induced Absorption of Hydrogen Containing Systems written by Hua-Kuang Lee and published by . This book was released on 2020 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Big Bang, hydrogen and helium were produced, with very small quantities of deuterium, tritium, and lithium. Due to gravitational attraction, the gases began to congregate. The conversion of gravitational potential energy to kinetic energy raised the temperature. For the gas clouds to continue to contract for form stars, some cooling mechanism was needed. In this thesis, ab initio calculations of collision-induced dipoles are reported, for use in evaluating collision-induced emission as a potential cooling mechanism during the formation of the first stars. In nonequilibrium conditions, molecular hydrogen and atomic hydrogen can coexist, so transient dipoles formed during collisions of molecular hydrogen with either molecular hydrogen or atomic hydrogen may contribute to cooling. The first stars that were formed in the universe are called Population III stars. This thesis includes calculations that are relevant to the observed radiative profiles of very old, very cool white dwarf stars. The detected radiation from the stars is a combination of the radiation from both the core and the stellar atmosphere. Radiation coming from the core may be absorbed by the atmosphere and then reemitted at a lower frequency. The core temperature and the radiative spectrum from the core can be evaluated by fitting the high-energy end of the spectrum with a black-body radiative profile. Often the radiative profile at lower energy does not fit the predicted profile, based on the core temperature. This is attributed to absorption in the stellar atmosphere, due to transient dipoles formed during collisions of hydrogen molecules with hydrogen atoms, helium atoms, or other hydrogen molecules.Due to the harsh conditions that are required for the existence of atomic hydrogen, experimental data collision-induced absorption involving atomic hydrogen is not available from experiment. Also, results at very high temperatures are not available from experiment. The collision-induced dipoles and collision-induced absorption spectra must be determined through computational work. The interest in atomic hydrogen for the astrophysical applications leads to the three research projects that are described in this thesis: 1) the dipole moment of the H2-H system in various configurations, 2) the energy and dipole moment of equilateral/isosceles triangular H3, and 3) the correlation energy and dipole of He-H.This thesis contains high-level ab initio computational results for all three projects, obtained with comparatively large basis sets. The results for H2-H are the best available. The collision-induced dipole has been expressed as a series in the spherical harmonics of the H2 bond vector and the intermolecular vector for various bond lengths and intermolecular separations. The calculated coefficients in this series are reported, and it is shown that the coefficients converge to the known analytical forms at long range. For H3, the energies of the three lowest states are reported as functions of the H-H separation and vertex angle in equilateral and isosceles triangular configurations. The conical intersection is located. For He-H, the calculated correlation energies and the correlation contribution to the dipole are shown to match the known long-range forms very accurately. The leading sp-charge density matrix on H shows the predicted R7 behavior. It appears that larger basis sets are required to show the same behavior at the He center.
Download or read book Collision induced Absorption of the First Overtone Bands of H2 and D2 written by Mahmoud Hasan Abu-Kharma and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Collision induced Absorption by Molecular Deuterium D2 in the Rototranslational Band the Fundamental Band and the First Overtone Band of written by Martin Andreas Abel and published by . This book was released on 2010 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electric charge distribution of molecules such as H2 and D2 is inversion-symmetric so that permanent dipole moments do not exist: such molecules are infrared-inactive. It is therefore interesting that gaseous, liquid, and solid hydrogen and its isotopes actually absorb infrared radiation, for example if gas densities are sufficiently high. The observed absorption arises from electric dipole moments induced by intermolecular interactions. It is of a supermolecular origin, due to binary (or higher-order) molecular complexes that may be transient (i.e., in a collisional encounter) or relatively stable (van-der-Waals molecule). Interaction-induced electric dipoles arise from the same mechanisms that generate the intermolecular forces: exchange forces, dispersion forces, and multipolar induction. Recently the induced dipole and potential energy surfaces of H2 pairs have been obtained by advanced quantum-chemical calculations. Interaction-induced absorption, more commonly called collision-induced absorption (CIA), by H2 pairs is an important opacity source in the atmospheres of various types of planets and cool stars, such as late stars, low-mass stars, brown dwarfs, certain white dwarfs, etc., and therefore of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra of their cores, mainly due to collision-induced absorption by collisional complexes of hydrogen and helium in the stellar atmospheres. Before proceeding to the frequencies and temperatures of interest it is good to check the new potential energy surface and induced dipole surface in all possible ways by comparison with existing isotopic laboratory measurements. Furthermore, the new potential energy surface is directly compared with previously available, well established intermolecular potential energy surfaces. The electric charge distributions of deuterium and hydrogen are very similar. The new potential energy and induced dipole surfaces were originally obtained to facilitate the computation of the collision-induced absorption of hydrogen. However, by replacing the rotovibrational wavefunctions of H2 with those of D2 the surfaces can also be used to calculate the collision-induced absorption of deuterium pairs, thereby probing them further. At the temperature of 298K existing measurements of the collision-induced absorption of D2--D2 gas are compared with our quantum scattering calculations in the D2 fundamental band (approximately 2,500cm−1 to 4,500cm−1). Furthermore, measurements of the collision-induced absorption of deuterium (D2) in the D2 first overtone band (about 5,250cm−1 to 7,250cm−1) at 201K are reported. These measurements are compared with ab initio calculations of the absorption spectra. Close agreement of measured and calculated spectra is seen.
Download or read book Collision induced Absorption in Gases written by Lothar Frommhold and published by . This book was released on 1993 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the theory and experiment of collision-induced absorption of infrared radiation in dense gases.
Download or read book Collision induced absorption of nitrogen methane and hydrogen methane pairs written by Michael Buser and published by . This book was released on 2004 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Density Effects in the Collision induced Absorption Spectra of Molecular Hydrogen written by James P. A. Youden and published by . This book was released on 1985 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Calculated Pressure induced Vibrational Absorption in H2 H2 Collisions in Hydrogen Gas written by R. W. Patch and published by . This book was released on 1971 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Technical Note written by and published by . This book was released on 1971 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Collision induced Absorption of Molecular Hydrogen in the First Overtone Region written by Edward Van Nostrand and published by . This book was released on 1981 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Theory of Collision induced Absorption and a Study of Gaseous written by Mary Moon and published by . This book was released on 1985 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Collisional Effects on Molecular Spectra written by Jean-Michel Hartmann and published by Elsevier. This book was released on 2008-08-12 with total page 429 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas phase molecular spectroscopy is a powerful tool for obtaining information on the geometry and internal structure of isolated molecules as well as on the interactions that they undergo. It enables the study of fundamental parameters and processes and is also used for the sounding of gas media through optical techniques. It has been facing always renewed challenges, due to the considerable improvement of experimental techniques and the increasing demand for accuracy and scope of remote sensing applications. In practice, the radiating molecule is usually not isolated but diluted in a mixture at significant total pressure. The collisions among the molecules composing the gas can have a large influence on the spectral shape, affecting all wavelength regions through various mechanisms. These must be taken into account for the correct analysis and prediction of the resulting spectra. This book reviews our current experimental and theoretical knowledge and the practical consequences of collisional effects on molecular spectral shapes in neutral gases. General expressions are first given. They are formal of difficult use for practical calculations often but enable discussion of the approximations leading to simplified situations. The first case examined is that of isolated transitions, with the usual pressure broadening and shifting but also refined effects due to speed dependence and collision-induced velocity changes. Collisional line-mixing, which invalidates the notion of isolated transitions and has spectral consequences when lines are closely spaced, is then discussed within the impact approximation. Regions where the contributions of many distant lines overlap, such as troughs between transitions and band wings, are considered next. For a description of these far wings the finite duration of collisions and concomitant breakdown of the impact approximation must be taken into account. Finally, for long paths or elevated pressures, the dipole or polarizability induced by intermolecular interactions can make significant contributions. Specific models for the description of these collision induced absorption and light scattering processes are presented. The above mentioned topics are reviewed and discussed from a threefold point of view: the various models, the available data, and the consequences for applications including heat transfer, remote sensing and optical sounding. The extensive bibliography and discussion of some remaining problems complete the text. State-of-the-art on the subject A bibliography of nearly 1,000 references Tools for practical calculations Consequences for other scientific fields Numerous illustrative examples Fulfilling a need since there is no equivalent monograph on the subject
Download or read book Simulation Study of Three Instrument Displays to Assist in Airplane Thrust Management written by Milton D. McLaughlin and published by . This book was released on 1970 with total page 802 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three displays were evaluated on a piloted simulator, each of which provided information which could be used in thrust management. The three displays were (1) rate of change of speed, (2) potential flight-path angle, and (3) potential rate of climb. Results are presented in the form of time histories, histograms, and pilot comments. The results include comparisons of flight-path and speed control and throttle activity with and without each display and pilot comments.
Download or read book Semiempirical Electric Dipole Moment and Its Derivative in H2 H2 and H2 H Collisions written by R. W. Patch and published by . This book was released on 1970 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Spectroscopy written by R F Barrow and published by Royal Society of Chemistry. This book was released on 2007-10-31 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: Specialist Periodical Reports provide systematic and detailed review coverage of progress in the major areas of chemical research. Written by experts in their specialist fields the series creates a unique service for the active research chemist, supplying regular critical in-depth accounts of progress in particular areas of chemistry. For over 80 years the Royal Society of Chemistry and its predecessor, the Chemical Society, have been publishing reports charting developments in chemistry, which originally took the form of Annual Reports. However, by 1967 the whole spectrum of chemistry could no longer be contained within one volume and the series Specialist Periodical Reports was born. The Annual Reports themselves still existed but were divided into two, and subsequently three, volumes covering Inorganic, Organic and Physical Chemistry. For more general coverage of the highlights in chemistry they remain a 'must'. Since that time the SPR series has altered according to the fluctuating degree of activity in various fields of chemistry. Some titles have remained unchanged, while others have altered their emphasis along with their titles; some have been combined under a new name whereas others have had to be discontinued. The current list of Specialist Periodical Reports can be seen on the inside flap of this volume.
