DOCSLIB.ORG

Crossed Molecular Beam: I

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Crossed Molecular Beam: I Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1984 Crossed molecular beam: I. Photoionization studies of hydrogen sulfide nda its dimer and trimer, II. A rotating source crossed molecular beam apparatus Harry Frank Prest Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Physical Chemistry Commons Recommended Citation Prest, Harry Frank, "Crossed molecular beam: I. Photoionization studies of hydrogen sulfide nda its dimer and trimer, II. A rotating source crossed molecular beam apparatus " (1984). Retrospective Theses and Dissertations. 9021. https://lib.dr.iastate.edu/rtd/9021 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This reproduction was made from a copy of a document sent to us for microfilming. While the most advanced technology has been used to photograph and reproduce this document, the quality of the reproduction is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help clarify markings or notations which may appear on this reproduction. 1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure complete continuity. 2. When an image on the film is obliterated with a round black mark, it is an indication of either blurred copy because of movement during exposure, duplicate copy, or copyrighted materials that should not have been filmed. For blurred pages, a good image of the page can be found in the adjacent frame. If copyrighted materials were deleted, a target note will appear listing the pages in the adjacent frame. 3. When a map, drawing or chart, etc., is part of the material being photographed, a definite method of "sectioning" the material has been followed. It is customary to begin filming at the upper left hand comer of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued again—beginning below the first row and continuing on until complete. 4. For illustrations that cannot be satisfactorily reproduced by xerographic means, photographic prints can be purchased at additional cost and inserted into your xerographic copy. These prints are available upon request from the Dissertations Customer Services Department. 5. Some pages in any document may have indistinct print. In all cases the best available copy has been filmed. UniversiV MicrOTlms International 300 N. Zeeb Road Ann Arbor, Ml 48106 8423666 Prest, Harry Frank CROSSED MOLECULAR BEAM: I. PHOTOIONIZATION STUDIES OF HYDROGEN-SULFIDE AND ITS DIMER AND TRIMER. II. A ROTATING SOURCE CROSSED MOLECULAR BEAM APPARATUS Iowa State University PH.D. 1984 University Microfilms Intsrnâtionsi 300 N. Zeeb Road, Ann Arbor, Ml 48106 PLEASE NOTE: in all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark -J . 1. Glossy photographs or pages \/ 2. Colored illustrations, paper or print 3. Photographs with dark background 4. Illustrations are poor copy \/ 5. Pages with black marks, not original copy 6. Print shows through as there is text on both sides of page 7. Indistinct, broken or small print on several pages 8. Print exceeds margin requirements 9. Tightly bound copy with print lost in spine 10. Computer printout pages with indistinct print 11. Page(s) lacking wfhen material received, and not available from school or author. 12. Page(s) seem to be missing in numbering only as text follows. 13. Two pages numbered . Text follows. 14. Curling and wrinkled pages 15. Other University Microfilms International Crossed molecular beam; I. Photoionization studies of hydrogen sulfide and its dimer and trimer II. A rotating source crossed molecular beam apparatus by Harry Frank Prest A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Chemistry Major: Physical Chemistry Approved: Members of the Committee: Signature was redacted for privacy. Signature was redacted for privacy. In Charge of Major Work Signature was redacted for privacy. the Maj( pa Signature was redacted for privacy. For Qfh^Gfâduate College Iowa State University Ames, Iowa 1984 i i TABLE OF CONTENTS Page DEDICATION iv ACKNOWLEDGEMENTS v GENERAL INTRODUCTION 1 Explanation of Thesis Format 4 PART I. PHOTOIONIZATION OF HYDROGEN SULFIDE AND ITS CLUSTERS 5 Introduction 5 References 12 SECTION I. MOLECULAR BEAM PHOTOIONIZATION STUDY OF H^S 14 Introduction 14 Experimental 15 Results and Discussion 18 References 37 SECTION II. PHOTOIONIZATION STUDY OF (HgS); AND (HgS)] 40 Introduction 40 Experimental 42 Results and Discussion 43 References 71 PART II. THE ROTATING SOURCE CROSSED MOLECULAR BEAM APPARATUS 74 Introduction 74 References 77 SECTION I. GENERAL CONSIDERATIONS AND DESIGN CRITERIA 73 Signal Considerations 78 Source Considerations 82 i i i Page Detector Design Considerations 85 The Rotating Detector Apparatus 86 References 93 SECTION II. THE ROTATING SOURCE APPARATUS 95 Apparatus Description 96 Characteristics of the Rotating Source Apparatus 133 Summary and Suggestions for Future Research 157 References 163 GENERAL CONCLUSIONS 168 APPENDIX A. PUMPING SPEED AND CONDUCTANCE 169 References 179 APPENDIX B. RSA EXPERIMENTAL CONTROL 180 Prest-X System Description 180 Prest-X Hardware 181 iV DEDICATION To my parents, grandparents, family and friends for their boundless love reflected in their unflagging encouragement and unconditional support. And to my teachers, Paul Harteck, Henry B. Hoi linger, Robert R. Reeves, Ernst Seglie, and Robert L. Strong who graciously and patiently encouraged and inspired a much less than promising student. These precious gifts I will forever treasure. V ACKNOWLEDGEMENTS Here I can list but a few of the many individuals that I am deeply grateful to for earnestly aiding me in my efforts. My thanks to Roland Struss and Norbert Cent for teaching me mechanical drawing and design and with whom I enjoyed many fruitful discussions. At one time or another, I've benefited from, and now thank, all the members of the Ames Laboratory Research Machine Shops, most especially Jerry Hand, Kent Mogard and Charles Burg. My thanks to Jerry Hand for finding the time and materials required. The majority of the rotating source apparatus was fabricated by Kent Mogard who did the impossible on a regular basis. Charles Burg performed rapid and vac-tight welding on everything from feedthroughs to the beam source chambers. I also greatly appreciate the efforts of the machinists of the ISU Chemistry Machine Shop, Eldon Ness, George Steininger and John Sauke, for taking care of the seemingly omnipresent emergency and "I needed it yesterday" stuff. My thanks to Harold Skank, John Erickson and Darv/in Lekwa of the Instrumentation Group for digging up all the parts and constructing all the in-house electronics, especially the controllers and microprocessor. Many thanks to Dr. Harry J. Svec for solving the difficult fiscal problems that made the RSA possible, advising me, and proofing this text. I am deeply indebted to Dr. H. Fritz Franzen for reminding me neither science nor the scientist are one-dimensional. I wish to thank Yoshi Ono, Steve H. Linn, Tzeng Wen-Bih (for "their part in obtaining the H^S data") and Shao Jian-Dong for sharing the encouraging discussions, frustrations, and absurd situations that have been graduate school. VI I will always be grateful for the mechanical talent reflected in the rotating source apparatus which is due to the man who showed me mechanical mastery and allowed me to make the thousands of mistakes necessary to acquire the small portion I possess; Mr. Samuel W. Prest, Sr. (and to Mrs. Maddy F. Prest who made sure each mistake was followed by the proper medical treatment). 1 GENERAL INTRODUCTION To someone who could grasp the universe from one unified viewpoint, the entire creation would appear as a unique fact and a great truth. J. D'Alembert The fundamental physical event is the collision; the primary process whereby information is obtained and exchanged. Seeking to understand the general nature of the collision and the participants, the event can be divided phenomenologically into: 1. an initial state 2. an intermediate state 3. a final state. The diversity of the manifestations and the information contained in the character of the collision event have required the development of numerous theoretical and experimental approaches. The molecular beam technique allows the preparation and study of unique species in an isolated environment. The singular nature of this environment permits a variety of spectroscopic techniques to be applied to the unperturbed species over relatively long time scales. Originally "simple" effusive sources, such as Knudsen ovens, were exclusively used; primarily due to the ease of maintaining the required vacuum. However, improvements in vacuum technology have allowed implementation of nonef- fusive sources, such as the supersonic nozzle source, with dramatic increases in the intensity of the collision participant(s) enabling the investigation of even less prominent processes. Further, an ever 2 increasing array of sensitive and specific detection techniques, each with its own advantages and disadvantages, are bringing more and more detail to our knowledge of molecular processes. The first part of this thesis examines the ionizing collision of a vacuum ultraviolet (VUV) photon with a molecular species. In general, the number of parameters accessible to experimental control or observa­ tion is limited: 1.
Load more

Recommended publications
  • University Microfilms International 300 N
    MOLECULAR BEAM KINETICS. Item Type text; Thesis-Reproduction (electronic) Authors Sentman, Judith Barlow. Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 03/10/2021 03:47:31 Link to Item http://hdl.handle.net/10150/274898 INFORMATION TO USERS This reproduction was made from a copy of a document sent to us for microfilming. While the most advanced technology has been used to photograph and reproduce this document, the quality of the reproduction is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help clarify markings or notations which may appear on this reproduction. 1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure complete continuity. 2. When an image on the film is obliterated with a round black mark, it is an indication of either blurred copy because of movement during exposure, duplicate copy, or copyrighted materials that should not have been filmed. For blurred pages, a good image of the page can be found in the adjacent frame. If copyrighted materials were deleted, a target note will appear listing the pages in the adjacent frame.
    [Show full text]
  • A Novel Crossed-Molecular-Beam Experiment for Investigating Reactions of State- and Conformationally Selected Strong-field-Seeking Moleculesa)
    A novel CMB setup for strong-field-seeking molecules A novel crossed-molecular-beam experiment for investigating reactions of state- and conformationally selected strong-field-seeking moleculesa) L. Ploenes,1 P. Straňák,1 H. Gao,1, 2 J. Küpper,3, 4, 5, 6 and S. Willitsch1, b) 1)Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland 2)Present address: Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China 3)Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany 4)Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany 5)Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany 6)Department of Chemistry, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany (Dated: 14 May 2021) The structure and quantum state of the reactants have a profound impact on the kinetics and dynamics of chemical reactions. Over the past years, significant advances have been made in the control and manipulation of molecules with external electric and magnetic fields in molecular-beam experiments for investigations of their state-, structure- and energy-specific chemical reactivity. Whereas studies for neutrals have so far mainly focused on weak-field-seeking species, we report here progress towards investigating reactions of strong-field-seeking molecules by introducing a novel crossed-molecular-beam experiment featuring an electrostatic deflector. The new setup enables the characteri- sation of state- and geometry-specific effects in reactions under single-collision conditions. As a proof of principle, we present results on the chemi-ionisation reaction of metastable neon atoms with rotationally state-selected carbonyl sulfide (OCS) molecules and show that the branching ratio between the Penning and dissociative ionisation pathways strongly depends on the initial rotational state of OCS.
    [Show full text]
  • Induced Fluorescence Spectroscopy of Li (2 PJ-2 5 112, A.=670.7 Nm) Between 700 and 1000 K John M
    A study of the reaction Li+ HCI by the technique of time-resolved laser­ 2 2 induced fluorescence spectroscopy of Li (2 PJ-2 5 112, A.=670.7 nm) between 700 and 1000 K John M. C. Plane and Eric S. Saltzman Rosenstiel School ofMarine and Atmospheric Science, University ofMiami, Miami, Florida 33149-1098 (Received 16 June 1987; accepted 9 July 1987) A kinetic study is presented of the reaction between lithium atoms and hydrogen chloride over the temperature range 700-1000 K. Li atoms are produced in an excess ofHCl and He bath gas by pulsed photolysis ofLiCl vapor. The concentration of the metal atoms is then monitored in real time by the technique of laser-induced fluorescence of Li atoms at A. = 670. 7 nm using a pulsed nitrogen-pumped dye laser and box-car integration of the fluorescence signal. Absolute second-order rate constants for this reaction have been measured at T = 700, 750, 800, and 900 K. At T = 1000 K the reverse reaction is sufficiently fast that equilibrium is rapidly established on the time scale of the experiment. A fit of the data between 700 and 900 K to the Arrhenius form, with 20' errors calculated from the absolute errors in the rate 10 3 1 constants, yields k(T) = (3.8 ± l.l) X 10- exp[ - (883 ± 218)/TJ cm molecule- • s- . This result is interpreted through a modified form of collision theory which is constrained to take account of the conservation of total angular momentum during the reaction. Thereby we 1 obtain an estimate for the reaction energy threshold, E0 = 8.2 ± 1.4 kJ mo1- (where the error arises from uncertainty in the exothermicity of the reaction), in very good agreement with a crossed molecular beam study of the title reaction, and substantially lower than estimates of E 0 from both semiempirical and ab initio calculations of the potential energy surface.
    [Show full text]
  • WO 2016/186536 Al 24 November 2016 (24.11.2016) P O P C T
    (12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date WO 2016/186536 Al 24 November 2016 (24.11.2016) P O P C T (51) International Patent Classification: BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, C01B 3/08 (2006.01) C01B 3/10 (2006.01) DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, HR, HU, ID, IL, IN, IR, IS, JP, KE, KG, KN, KP, KR, (21) International Application Number: KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, ME, MG, PCT/SE20 15/000030 MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, (22) International Filing Date: PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA, SC, 15 May 2015 (15.05.2015) SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (25) Filing Language: English (84) Designated States (unless otherwise indicated, for every (26) Publication Language: English kind of regional protection available): ARIPO (BW, GH, (71) Applicant: HYDROATOMIC INST /INFORMATION- GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, ST, SZ, STJANST I SOLNA AB [SE/SE]; Boforsgatan 27, 123 TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, 46 Farsta (SE). TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, (72) Inventor: PRYTZ, Sven-Erik; Angsklockevagen 26, LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, 18157 Lidingo (SE).
    [Show full text]
  • Lawrence Berkeley Laboratory UNIVERSITY of CALIFORNIA Materials & Molecular Research Division
    LBL-10863 c..~ Preprint Lawrence Berkeley Laboratory UNIVERSITY OF CALIFORNIA Materials & Molecular Research Division Submitted to the Journal of Chemical Physics MASS AND ORIENTATION EFFECTS IN DISSOCIATIVE COLLISIONS BETWEEN RARE GAS ATOMS AND ALKALI HALIDE MOLECULES F. P. Tully, N. H. Cheung, H. Haberland, and Y. T. Lee "'::CEfVcA.,. !.:~ v'.r~r,:NG': :m::E!.EY l.ABORATORV May 1980 JUN 20 1980 TWO-WEEK LOAN COpy This is a Library Circulating Copy which may be borrowed for two weeks. For.a personal retention copy~ call Tech. Info. Division~ Ext. 6782. r ()) r} ._ r -l Prepared for the U.S. Department of Energy under Contract W-7405-ENG-48 DISCLAIMER This document was prepared as an account of work sponsored by the United States, Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor the Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or the Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or the Regents of the University of California.
    [Show full text]
  • MARK, NICHOLAS R., M.S. a New Crossed Molecular Beam Apparatus for the Study of the Cl + O 3 Reaction Probed Via Direct Absorption of Millimeter/Submillimeter- Waves
    MARK, NICHOLAS R., M.S. A New Crossed Molecular Beam Apparatus for the Study of the Cl + O 3 Reaction Probed Via Direct Absorption of Millimeter/Submillimeter- Waves. (2012) Directed by Dr. Liam M. Duffy. 87 pp. For decades, molecular beam scattering experiments have been used to understand the forces and dynamics that are involved in chemical reactions at the quantum mechanical level. Using millimeter/submillimeter-waves the dynamics for the scattering of a bimolecular collision can be probed via pure rotational spectroscopy. Focus of this research is the reaction between ozone and chlorine, which has been widely studied due its key role in the catalytic destruction cycle of ozone in the atmosphere. For this research, a new crossed molecular beam apparatus was successfully designed and constructed. The apparatus consists of independently rotating arms to allow for reactants to be collided at a wide range of angles, and therefore relative velocities, and can easily be adapted for use in numerous types of scattering experiments. Ozone was successfully created and trapped to produce a molecular beam, which has been characterized from a pinhole and slit nozzle. Though no products have been seen from the experiments to date, the critical work has been completed so the system can be optimized in the future. A NEW CROSSED MOLECULAR BEAM APPARATUS FOR THE STUDY OF THE Cl + O 3 REACTION PROBED VIA DIRECT ABSORPTION OF MILLIMETER/SUBMILLIMETER-WAVES by Nicholas R. Mark A Thesis Submitted to The Faculty of the Graduate School at The University of North Carolina at Greensboro in Partial Fulfillment of the Requirements for the Degree Master of Science Greensboro 2012 Approved by ___________________________ Committee Chair APPROVAL PAGE This thesis has been approved by the following committee of the Faculty of the Graduate School at the University of North Carolina at Greensboro.
    [Show full text]
  • Collisions Between Cold Molecules in a Superconducting Magnetic Trap
    Collisions between cold molecules in a superconducting magnetic trap Yair Segev*, Martin Pitzer*, Michael Karpov*, Nitzan Akerman, Julia Narevicius and Edvardas Narevicius Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel. Abstract Collisions between cold molecules are essential for studying fundamental aspects of quantum chemistry, and may enable formation of quantum degenerate molecular matter by evaporative cooling. However, collisions between trapped, naturally occurring molecules have so far eluded direct observation due to the low collision rates of dilute samples. We report the first directly observed collisions between cold, trapped molecules, achieved without the need of laser cooling. We magnetically capture molecular oxygen in a 0.8K∙kB deep superconducting trap, and set bounds on the ratio between the elastic and inelastic scattering rates, the key parameter determining the feasibility of evaporative cooling. We further co-trap and identify collisions between atoms and molecules, paving the way to studies of cold interspecies collisions in a magnetic trap. Introduction Cold bimolecular collisions play a central role in a variety of processes, including interstellar chemistry1, and are used for the detailed examination of fundamental physics in two-body interactions2–5 and the preparation of new states of quantum matter6. Experimental efforts started with the pioneering work of Herschbach and Lee7, with the first use of a crossed molecular beam apparatus for physical chemistry. State of the art experiments in moving frames of reference are ever pushing the limits to lower collision energies8–12, but the low collision rates associated with such cold, dilute gases eventually necessitate trapping for long durations.
    [Show full text]
  • Crossed Molecular Beam Experiments of Radical-Neutral Reactions Relevant to the Formation of Hydrogen Deficient Molecules in Extraterrestrial Environments
    Astrochemistry: From Molecular Clouds to Planetary Systems IA U Symposium, Vol. 197, 2000 Y. C. Minh and E. F. van Dishoeck, eds. Crossed Molecular Beam Experiments of Radical-Neutral Reactions Relevant to the Formation of Hydrogen Deficient Molecules in Extraterrestrial Environments R. I. Kaiser!, N. Balucani/, O. Asvany", and Y. T. Lee Institute of Atomic and Molecular Sciences, 1, Section 4, Roosevelt Rd., 107 Taipei, Taiwan, ROC Abstract. During the last 5 years, laboratory experiments relevant to the formation of carbon-bearing molecules in extraterrestrial environ- ments have been performed employing the crossed molecular beam tech- nique and a high intensity source of ground state atomic carbon, C(3Pj ). These investigations unraveled for the first time detailed information on the chemical reaction dynamics, involved collision complexes and inter- mediates, and - most important - reaction products of neutral-neutral reactions. Here, we extend these studies even further, and report on very recent crossed beam experiments of cyano radical, CN(2~+), reac- tions with unsaturated hydrocarbons to form nit riles in extraterrestrial environments and Saturn's moon Titan. Further, preliminary results on reactions of small carbon clusters C2(1 ~t), and C3 (1~t) with acetylene, ethylene, and methylacetylene to synthesize hydrogen-deficient carbon- bearing molecules are presented. 1. Introduction In the gas phase of the interstellar medium (ISM), about 97% of all molecular species are neutral, whereas only 3% are ions (Scheffler & Elsasser 1988). These ions, radicals, and closed shell molecules are predominantly confined to distinct interstellar environments such as interstellar clouds, hot cores, and circumstellar envelopes of dying carbon and oxygen stars.
    [Show full text]
  • Lawrence Berkeley Laboratory
    LBL-23925 Lawrence Berkeley Laboratory UNIVERSITY OF CALIFORNIA Materials & Chemical Sciences Division Published as a chapter in Nobel Prize Winners, H.W. Wilson Company, New York, NY, August 1987 Yuan T. Lee - 1986 Nobel Prize in Chemistry •' :C *j H.F. Schaefer III I. June 1987 TWOWEEK.LOAN COPY. This is a LiSrary..Circulating Copy which thay be borrowed for two we .. ,ZIM R .. A. low - Su ) fl Prepared for the U.S. Department of Energy under Contract DE-AC03-76SF00098 DISCLAIMER This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor the Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or the Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or the Regents of the University of California. Yuan T. Lee - 1986 Nobel Prize in Chemistry * Henry F. Schaefer III Department of Chemistry, and Lawrence Berkeley Laboratory University of California, Berkeley, California 94720 To appear in the book Nobel Prize Winners, published by the H.
    [Show full text]
  • Arxiv:2012.10470V1 [Physics.Atom-Ph] 18 Dec 2020 Contents II Acknowlegements VIII
    Molecular Collisions: from Near-cold to Ultra-cold Yang Liu1, ∗ and Le Luo1, † 1School of Physics and Astronomy, Sun Yat-Sen University, Zhuhai, 519082, China (Dated: December 22, 2020) In the past two decades, the revolutionary technologies of creating cold and ultracold molecules have provided cutting-edge experiments for studying the fundamental phenomena of collision physics. To a large degree, the recent explosion of interest in the molecular collisions has been sparked by dramatic progress of experimental capabilities and theoretical methods, which permit molecular collisions to be explored deep in the quantum mechanical limit. Tremendous experimental advances in the field has already been achieved, and the authors, from an experimental perspective, provide a review of these studies for exploring the nature of molecular collisions occurring at tem- peratures ranging from the Kelvin to the nanoKelvin regime, as well as for applications of producing ultracold molecules. PACS numbers: 34.10.+x, 34.20.-b, 34.20.Gj, 34.50.Lf Contents References 29 I. Introduction 1 I. Introduction II. Theory of molecular collisions 2 Collision processes governed by intra-particle interac- A. Potential energy surface 2 tion play a pivotal role in nuclear physics, condensed mat- B. Scattering theory 4 ter physics, atomic and molecular physics, and chemistry. 1. Quantum capture theory 4 Understanding the quantum nature of these collisions 2. Wigner threshold laws 8 is important for controlling chemical reaction, precision 3. Quantum defect theory 9 measurement, improving energy efficiency, and exploring novel phases of matter. Quantum collisions related to III. Experiment: Near cold collision 10 chemical kinetics and reaction dynamics have been stud- A.
    [Show full text]
  • Electric-Field Affected Low-Energy Collisions Between Co-Trapped
    Electric-Field Affected Low-Energy Collisions between Co-Trapped Ammonia and Rubidium by L. Paul Parazzoli B.S., University of Washington, 2001 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Physics 2010 This thesis entitled: Electric-Field Affected Low-Energy Collisions between Co-Trapped Ammonia and Rubidium written by L. Paul Parazzoli has been approved for the Department of Physics Heather J. Lewandowski Thomas Schibli Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. iii Parazzoli, L. Paul (Ph.D., Physics) Electric-Field Affected Low-Energy Collisions between Co-Trapped Ammonia and Rubidium Thesis directed by Prof. Heather J. Lewandowski This thesis describes the effect of an electric field on the interaction between rubidium and ammonia at 100 mK. The ability to study low energy interactions between molecules and atoms provides new tools to understand how the processes that govern these interactions work. For example, the use of external electric and magnetic fields provides tools to spatially orient molecules to show how this affects the dynamics of the interaction. The use of electric fields have been proposed to affect dipole-dipole interactions, however we have showed that the space-orienting effect of the field can have a significant effect even in the absence of dipole-dipole interaction. To measure this effect, we trap ammonia molecules in a single quantum state using an electrostatic trap.
    [Show full text]
  • Constructing Velocity Distributions in Crossed-Molecular Beam Studies Using Fourier Transform Doppler Spectroscopy
    MONGE, JOSUÉ ROBERTO, M.S. Constructing Velocity Distributions in Crossed- Molecular Beam Studies using Fourier Transform Doppler Spectroscopy. (2012) Directed by Liam M. Duffy. 74 pp. The goal of our scattering experiments is to derive the distribution the differential cross-section and elucidate the dynamics of a bimolecular collision via pure rotational spectroscopy. We have explored the use of a data reduction model to directly trans- form rotational line shapes into the differential cross section and speed distribution of a reactive bimolecular collision. This inversion technique, known as Fourier Transform Doppler Spectroscopy (FTDS), initially developed by James Kinsey [1], deconvolves the velocity information contained in one-dimensional Doppler Profiles to construct the non-thermal, state-selective three-dimensional velocity distribution. By employ- ing an expansion in classical orthogonal polynomials, the integral transform in FTDS can be simplified into a set of purely algebraic expressions technique; i.e. the Taatjes method [2]. In this investigation, we extend the Taatjes method for general use in recovering asymmetric velocity distributions. We have also constructed a hypothet- ical asymmetric distribution from adiabatic scattering in Argon–Argon to test the general method. The angle- and speed-components of the sample distribution were derived classically from a Lennard-Jones 6-12 potential, with collisions at 60 meV, and mapped onto Radon space to generate a set of discrete Doppler profiles. The sample distribution was reconstructed from these profiles using FTDS. Both distri- butions were compared along with derived total cross sections for the Argon–Argon system. This study serves as a template for constructing velocity distributions from bimolecular scattering experiments using the FTDS inversion technique.
    [Show full text]