Advances in Asymmetric Autocatalysis and Related Topics 1St Edition Download Free
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Understanding the Bonding of Second Period Diatomic Molecules Spdf Vs MCAS
Understanding the Bonding of Second Period Diatomic Molecules Spdf vs MCAS By Joel M Williams (text and images © 2013) The html version with updates and higher resolution images is at the author’s website (click here) Abstract The current spdf and MO modeling of chemical molecules are well-established, but do so by continuing to assume that non-classical physics is operating. The MCAS electron orbital model is an alternate particulate model based on classical physics. This paper describes its application to the diatomic molecules of the second period of the periodic table. In doing so, it addresses their molecular electrostatics, bond strengths, and electron affinities. Particular attention is given to the anomalies of the carbon diatom. Questions are raised about the sensibleness of the spdf model’s spatial ability to contain two electrons on an axis between diatoms and its ability to form π-bonds from parallel p-orbitals located over the nuclei of each atom. Nitrogen, carbon monoxide, oxygen, and fluorine all have the same inter-nuclei bonding: all “triple bonds” of varying strength caused by different numbers of anti-bonding electrons. The spdf model was devised for single atoms by physicists and mathematicians. Kowtowing to them, chemists produce hybrid orbitals to explain how atoms could actually form molecules. Drawing these hybrids and meshing them on paper might look great, but, constrained to measured interatomic physical dimensions and electrostatic interactions, bonding based on the spdf-hybrids (sp, sp2, sp3) is illogical. To have even one electron occupy the “bond” region between the nuclei of diatomic molecules, at the expense of reduced coverage elsewhere, does not make sense for stable molecules. -
Determination of Aluminium As Oxide
DETERMINATION OF ALUMINIUM AS OXIDE By William Blum CONTENTS Page I. Introduction 515 II. General principles 516 III. Historical 516 IV. Precipitation of aluminium hydroxide. 518 1. Hydrogen electrode studies 518 (a) The method 518 (b) Apparatus and solutions employed 518 (c) Results of hydrogen electrode experiments 519 (d) Conclusions from hydrogen electrode experiments 520 2. Selection of an indicator for denning the conditions of precipita- '. tion . 522 3. Factors affecting the form of the precipitate 524 4. Precipitation in the presence of iron 525 V. Washing the precipitate . 525 VI. Separation from other elements 526 VII. Ignition and weighing of the precipitate 528 1. Hygroscopicity of aluminium oxide 529 2. Temperature and time of ignition 529 3. Effect of ammonium chloride upon the ignition 531 VIII. Procedure recommended 532 IX. Confirmatory experiments 532 X. Conclusions '534 I. INTRODUCTION Although a considerable number of precipitants have been pro- posed for the determination of aluminium, direct precipitation of aluminium hydroxide by means of ammonium hydroxide, fol- lowed by ignition to oxide, is most commonly used, especially if no separation from iron is desired, in which latter case special methods must be employed. While the general principles involved in this determination are extremely simple, it has long been recog- nized that certain precautions in the precipitation, washing, and ignition are necessary if accurate results are to be obtained. While, however, most of these details have been studied and dis- cussed by numerous authors, it is noteworthy that few publica- tions or textbooks have taken account of all the factors. In the 515 ; 516 Bulletin of the Bureau of Standards [Voi.i3 present paper it seems desirable, therefore, to assemble the various recommendations and to consider their basis and their accuracy. -
Discharge Plasmas of Molecular Gases
/ J ¥4~r~~~: 'o j~ ~7 ~,~U;~I u t= ~]f~LL*~ ~~~~~~; 4. Isotope Separation in Discharge Plasmas of Molecular Gases EZOUBTCHENKO, Alexandre N.t, AKATSUKA Hiroshi and SUZUKI Masaaki Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152-8550, Japan (Received 25 December 1997) Abstract We review the theoretical principles and the experimental methods of isotope separation achieved through the use of discharge plasmas of molecular gases. Isotope separation has been accomplished in various plasma chemical reactions. It is experimentally and theoretically shown that a state of non- equilibrium in the plasmas, especially in the vibrational distribution functions, is essential for the isotope redistribution in the reagents and products. Examples of the reactions, together with the isotope separ- ation factors known up to the present time, are shown to separate isotopic species of carbon, nitrogen and oxygen molecules in the plasma phase, generated by glow discharge and microwave discharge. Keywords: isotope separation, vibrational nonequilibrium, glow discharge, microwave discharge, plasma chemistry 4.1 Introduction isotopic species will be redistributed between the rea- Plasmas generated by electric discharge of molecu- gents and the products. We can elaborate a new lar gases under moderate pressures (10 Torr < p < method of the plasma isotope separation for light ele- 200 Torr) are usually in a state of nonequilibrium. We ments . can define various temperatures according to the kine- There were a few experimental studies of isotope tics of various particles in such plasmas, for example, separation phenomena in the nonequilibrium electric electron temperature ( T*), gas translational temperature discharge. Semiokhin et al. measured C02 enrichment ( To), gas rotational temperature ( TR) and vibrational in i3C02 and 12C160180 with a separation factor a ~ temperature ( Tv), where the relationships T* > Tv ;~ 1.01 in the C02 Silent (barrier) discharge in the pres- TR- To usually hold. -
©2018 Alexander Hook ALL RIGHTS RESERVED
©2018 Alexander Hook ALL RIGHTS RESERVED A DFT STUDY OF HYDROGEN ABSTRACTION FROM LIGHT ALKANES: Pt ALLOY DEHYDROGENATION CATALYSTS AND TIO2 STEAM REFORMING CATALYSTS By ALEXANDER HOOK A dissertation submitted to the School of Graduate Studies Rutgers, The State University of New Jersey In partial fulfillment of the requirements For the degree of Doctor of Philosophy Graduate Program in Chemical and Biochemical Engineering Written under the direction of Fuat E. Celik And approved by __________________________ __________________________ __________________________ __________________________ New Brunswick, New Jersey May, 2018 ABSTRACT OF THE DISSERTATION A DFT STUDY OF HYDROGEN ABSTRACTION FROM LIGHT ALKANES: Pt ALLOY DEHYDROGENATION CATALYSTS AND TiO2 STEAM REFORMING CATALYSTS By ALEC HOOK Dissertation Director: Fuat E. Celik Sustainable energy production is one of the biggest challenges of the 21st century. This includes effective utilization of carbon-neutral energy resources as well as clean end-use application that do not emit CO2 and other pollutants. Hydrogen gas can potentially solve the latter problem, as a clean burning fuel with very high thermodynamic energy conversion efficiency in fuel cells. In this work we will be discussing two methods of obtaining hydrogen. The first is as a byproduct of light alkane dehydrogenation where we obtain a high value olefin along with hydrogen gas. The second is in methane steam reforming where hydrogen is the primary product. Chapter 1 begins by introducing the reader to the current state of the energy industry. Afterwards there is an overview of what density functional theory (DFT) is and how this computational technique can elucidate and complement laboratory experiments. It will also contain the general parameters and methodology of the VASP software package that runs the DFT calculations. -
A Chemical Kinetics Network for Lightning and Life in Planetary Atmospheres P
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by St Andrews Research Repository The Astrophysical Journal Supplement Series, 224:9 (33pp), 2016 May doi:10.3847/0067-0049/224/1/9 © 2016. The American Astronomical Society. All rights reserved. A CHEMICAL KINETICS NETWORK FOR LIGHTNING AND LIFE IN PLANETARY ATMOSPHERES P. B. Rimmer and Ch Helling School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK; [email protected] Received 2015 June 3; accepted 2015 October 22; published 2016 May 23 ABSTRACT There are many open questions about prebiotic chemistry in both planetary and exoplanetary environments. The increasing number of known exoplanets and other ultra-cool, substellar objects has propelled the desire to detect life andprebiotic chemistry outside the solar system. We present an ion–neutral chemical network constructed from scratch, STAND2015, that treats hydrogen, nitrogen, carbon, and oxygen chemistry accurately within a temperature range between 100 and 30,000 K. Formation pathways for glycine and other organic molecules are included. The network is complete up to H6C2N2O3. STAND2015 is successfully tested against atmospheric chemistry models for HD 209458b, Jupiter, and the present-day Earth using a simple one- dimensionalphotochemistry/diffusion code. Our results for the early Earth agree with those of Kasting for CO2,H2, CO, and O2, but do not agree for water and atomic oxygen. We use the network to simulate an experiment where varied chemical initial conditions are irradiated by UV light. The result from our simulation is that more glycine is produced when more ammonia and methane is present. -
Chapter 10 Theories of Electronic Molecular Structure
Chapter 10 Theories of Electronic Molecular Structure Solving the Schrödinger equation for a molecule first requires specifying the Hamiltonian and then finding the wavefunctions that satisfy the equation. The wavefunctions involve the coordinates of all the nuclei and electrons that comprise the molecule. The complete molecular Hamiltonian consists of several terms. The nuclear and electronic kinetic energy operators account for the motion of all of the nuclei and electrons. The Coulomb potential energy terms account for the interactions between the nuclei, the electrons, and the nuclei and electrons. Other terms account for the interactions between all the magnetic dipole moments and the interactions with any external electric or magnetic fields. The charge distribution of an atomic nucleus is not always spherical and, when appropriate, this asymmetry must be taken into account as well as the relativistic effect that a moving electron experiences as a change in mass. This complete Hamiltonian is too complicated and is not needed for many situations. In practice, only the terms that are essential for the purpose at hand are included. Consequently in the absence of external fields, interest in spin- spin and spin-orbit interactions, and in electron and nuclear magnetic resonance spectroscopy (ESR and NMR), the molecular Hamiltonian usually is considered to consist only of the kinetic and potential energy terms, and the Born- Oppenheimer approximation is made in order to separate the nuclear and electronic motion. In general, electronic wavefunctions for molecules are constructed from approximate one-electron wavefunctions. These one-electron functions are called molecular orbitals. The expectation value expression for the energy is used to optimize these functions, i.e. -
Directed Gas Phase Formation of Silicon Dioxide and Implications for the Formation of Interstellar Silicates
ARTICLE DOI: 10.1038/s41467-018-03172-5 OPEN Directed gas phase formation of silicon dioxide and implications for the formation of interstellar silicates Tao Yang 1,2, Aaron M. Thomas1, Beni B. Dangi1,3, Ralf I. Kaiser 1, Alexander M. Mebel 4 & Tom J. Millar 5 1234567890():,; Interstellar silicates play a key role in star formation and in the origin of solar systems, but their synthetic routes have remained largely elusive so far. Here we demonstrate in a combined crossed molecular beam and computational study that silicon dioxide (SiO2) along with silicon monoxide (SiO) can be synthesized via the reaction of the silylidyne radical (SiH) with molecular oxygen (O2) under single collision conditions. This mechanism may provide a low-temperature path—in addition to high-temperature routes to silicon oxides in circum- stellar envelopes—possibly enabling the formation and growth of silicates in the interstellar medium necessary to offset the fast silicate destruction. 1 Department of Chemistry, University of Hawai’iatMānoa, Honolulu, HI 96822, USA. 2 State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China. 3 Department of Chemistry, Florida Agricultural and Mechanical University, Tallahassee, FL 32307, USA. 4 Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA. 5 Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN, UK. Correspondence and requests for materials should be addressed to R.I.K. (email: [email protected]) or to A.M.M. (email: mebela@fiu.edu) or to T.J.M. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:774 | DOI: 10.1038/s41467-018-03172-5 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/s41467-018-03172-5 — 28 + 28 + he origin of interstellar silicate grains nanoparticles ( SiO2 ), and 44 ( SiO ). -
Gas Phase Formation of C-Sic3 Molecules in the Circumstellar Envelope of Carbon Stars
Gas phase formation of c-SiC3 molecules in the circumstellar envelope of carbon stars Tao Yanga,b,1,2, Luke Bertelsc,1, Beni B. Dangib,3, Xiaohu Lid,e, Martin Head-Gordonc,2, and Ralf I. Kaiserb,2 aState Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China; bDepartment of Chemistry, University of Hawai‘iatManoa, Honolulu, HI 96822; cDepartment of Chemistry, University of California, Berkeley, CA 94720; dXinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China; and eNational Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, P. R. China Contributed by Martin Head-Gordon, May 17, 2019 (sent for review July 20, 2018; reviewed by Piergiorgio Casavecchia and David Clary) Complex organosilicon molecules are ubiquitous in the circumstel- Modern astrochemical models propose that the very first lar envelope of the asymptotic giant branch (AGB) star IRC+10216, silicon–carbon bonds are formed in the inner envelope of the but their formation mechanisms have remained largely elusive until carbon star, which is undergoing mass loss at the rates of several − now. These processes are of fundamental importance in initiating a 10 5 solar masses per year (22, 23). Pulsations from the central chain of chemical reactions leading eventually to the formation of star may initiate shocks, which (photo)fragment the circumstellar — organosilicon molecules among them key precursors to silicon car- materials (24, 25). These nonequilibrium conditions cause tem- — bide grains in the circumstellar shell contributing critically to the peratures of 3,500 K or above (19) and lead to highly reactive galactic carbon and silicon budgets with up to 80% of the ejected metastable fragments such as electronically excited silicon atoms, materials infused into the interstellar medium. -
Alcl3(G)=3Alcl(G) Reaction in the Subhalide Process of Aluminium (Study of Extractive Metallurgy of Aluminium (1))
Equilibrium of the 2Al(l)+AlCl3(g)=3AlCl(g) Reaction in the Subhalide Process of Aluminium (Study of Extractive Metallurgy of Aluminium (1)) By Takeaki Kikuchi*, Toshio Kurosawa* and Testuo Yagihashi* Equilibriumconstants of a fundamental reaction of the aluminium subhalide process, 2Al(l)+AlCl3(g)= 3AlCl(g), were determined by the flow method using argon carrier between 1000℃ and 1250℃. As a result of this experiment, equilibrium constants and standard free energy were obtained by the following equation: The heat of formation and entropy of AlCl(g) obtained from the experimental data and other thermodynamic values were -22,250cal/mot and 48.7cal/mol respectively. By the use of the equilibrium constants, the reaction ratio of aluminium trichloride was calculated at a reduced pressure and in argon carrier, respectively. (Receivedmarch 10, 1964) I. Introduction trichloride supplied to the reaction zone were applied Aluminium is produced by means of the fused salt previously. In this investigation, the latter method electrolysis using alumina obtained mainly from rela- was selected to obtain the equilibrium constants. tively higher grade bauxite. However, another 1. Experimental apparatus extraction method called the Gross or subhalide process has recently been investigated, and some technological The apparatus used in this experiment is shown by or industrialization reports have already been the schematic diagram in Fig. 1. The apparatus con- sists of an argon purifier, aluminium trichloride evapora- published. In this process, crude aluminium alloy is produced tor, reaction tube, and condensing tube of aluminium by reduction of alumina bearing ores with carbonaceous trichloride gas. Argon in a bomb was purified and reducing material such as coke or charcoal in the measured by passing through concentrated sulphuric acid, calcium chloride, soda lime, phosphorus pentoxide first step, and then aluminium trichloride gas is alld magnesium chip hea七ed at 400℃. -
Rotational Spectroscopy of the Isotopic Species of Silicon Monosulfide, Sisw
PAPER www.rsc.org/pccp | Physical Chemistry Chemical Physics Rotational spectroscopy of the isotopic species of silicon monosulfide, SiSw H. S. P. Mu¨ller,*ab M. C. McCarthy,cd L. Bizzocchi,e H. Gupta,cdf S. Esser,g H. Lichau,a M. Caris,a F. Lewen,a J. Hahn,g C. Degli Esposti,e S. Schlemmera and P. Thaddeuscd Received 2nd January 2007, Accepted 23rd January 2007 First published as an Advance Article on the web 20th February 2007 DOI: 10.1039/b618799d Pure rotational transitions of silicon monosulfide (28Si32S) and its rare isotopic species have been observed in their ground as well as vibrationally excited states by employing Fourier transform microwave (FTMW) spectroscopy of a supersonic molecular beam at centimetre wavelengths (13–37 GHz) and by using long-path absorption spectroscopy at millimetre and submillimetre wavelengths (127–925 GHz). The latter measurements include 91 transition frequencies for 28Si32S, 28Si33S, 28Si34S, 29Si32S and 30Si32Sinu = 0, as well as 5 lines for 28Si32Sinu = 1, with rotational quantum numbers J00 r 52. The centimetre-wave measurements include more than 300 newly recorded lines. Together with previous data they result in almost 600 transitions (J00 =0 and 1) from all twelve possible isotopic species, including 29Si36S and 30Si36S, which have fractional abundances of about 7 Â 10À6 and 4.5 Â 10À6, respectively. Rotational transitions were observed from u = 0 for the least abundant isotopic species to as high as u = 51 for the main species. Owing to the high spectral resolution of the FTMW spectrometer, hyperfine structure from the nuclear electric quadrupole moment of 33S was resolved for species containing this isotope, as was much smaller nuclear spin-rotation splitting for isotopic species involving 29Si. -
Product Detection of the CH Radical Reactions with Ammonia and Methyl-Substituted Amines Jérémy Bourgalais, Kacee L
Product Detection of the CH Radical Reactions with Ammonia and Methyl-Substituted Amines Jérémy Bourgalais, Kacee L. Caster, Olivier Durif, David L. Osborn, Sébastien D. Le Picard, Fabien Goulay To cite this version: Jérémy Bourgalais, Kacee L. Caster, Olivier Durif, David L. Osborn, Sébastien D. Le Picard, et al.. Product Detection of the CH Radical Reactions with Ammonia and Methyl-Substituted Amines. Journal of Physical Chemistry A, American Chemical Society, 2019, 123 (11), pp.2178-2193. 10.1021/acs.jpca.8b11688. hal-02089225 HAL Id: hal-02089225 https://hal-univ-rennes1.archives-ouvertes.fr/hal-02089225 Submitted on 11 Apr 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Page 1 of 47 The Journal of Physical Chemistry 1 2 3 Product Detection of the CH Radical Reactions with Ammonia and 4 5 6 Methyl-Substituted Amines 7 8 1 2 3 4 9 Jeremy Bourgalais, Kacee L. Caster, Olivier Durif, David L. Osborn, Sebastien D. Le 10 11 Picard,3 and Fabien Goulay2,* 12 13 1 LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, 14 -
Diatomic Carbon Measurements with Laser-Induced Breakdown Spectroscopy
University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Masters Theses Graduate School 5-2015 Diatomic Carbon Measurements with Laser-Induced Breakdown Spectroscopy Michael Jonathan Witte University of Tennessee - Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_gradthes Part of the Atomic, Molecular and Optical Physics Commons, and the Plasma and Beam Physics Commons Recommended Citation Witte, Michael Jonathan, "Diatomic Carbon Measurements with Laser-Induced Breakdown Spectroscopy. " Master's Thesis, University of Tennessee, 2015. https://trace.tennessee.edu/utk_gradthes/3423 This Thesis is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Masters Theses by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a thesis written by Michael Jonathan Witte entitled "Diatomic Carbon Measurements with Laser-Induced Breakdown Spectroscopy." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Master of Science, with a major in Physics. Christian G. Parigger, Major Professor We have read this thesis and recommend its acceptance: Horace Crater, Joseph Majdalani Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Diatomic Carbon Measurements with Laser-Induced Breakdown Spectroscopy A Thesis Presented for the Master of Science Degree The University of Tennessee, Knoxville Michael Jonathan Witte May 2015 c by Michael Jonathan Witte, 2015 All Rights Reserved.