Photoionization of Kcs Molecule: Origin of the Structured Continuum?
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On the Photoionization of Large Molecules
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector ________ ~~__ On the Photoionization of Large Molecules C. H. Becker and K. J. Wu* Molecular Phvxics L‘tbordtorv, SRI Irlternatmnal, Menlo Park. ialifornia, USA There is no apparent limit to the size of a molecule for which photoionization can occur. It is argued that it is difficult to obtain useful photoionization mass spectra of peptides (above - 2000 u), proteins, and oligonucleotides, because of the high internal energy of these polar molecules as a result of the desorption event and because vibrationally excited radical cations readily fragment. Evidence to support this hypothesis is presented from the 1%nm single-photon ionization 61’1) mass spectra of the cyclic decapeptide gramicidin S and of fullerencs, from null SPI results with the linear peptides substance P and gramicidin D and oligonucleotides, and from a variety of data found in the literature. The literature data include mass spectra from jet-cooled peptides, perfluorinated polyethers, collisional ioniza- tion of small neutral peptides, and the ultraviolet photoelectron spectroscopy of polymeric solids. (1 Am Sot Mass Spcctrom 1995, 6, 883-888) uch recent effort in mass spectrometry has (MALD), peptides and proteins show significant de- been directed toward the analysis of peptides grees of metastable decay that increases with the mass M and proteins [l, 21, DNA [3, 41, and other of the molecule [ll]. Even for the MALD technique, large biopolymers. Successful analytical approaches to considered currently to be the “gentlest” of all stimu- date have used the direct ionization associated with lated desorption techniques in that it permits observa- the desorption process, especially with laser desorp- tion of the quasimolecular ions of large proteins and tion. -
Improved Treatment of the Photoionization Process in the Laser Induced Optical Breakdown in the Laser Tissue
U.P.B. Sci. Bull., Series A, Vol. 81, Iss. 4, 2019 ISSN 1223-7027 IMPROVED TREATMENT OF THE PHOTOIONIZATION PROCESS IN THE LASER INDUCED OPTICAL BREAKDOWN IN THE LASER TISSUE Violeta PETROVIĆ1 and Hristina DELIBAŠIĆ1 The development of laser technology led to the discovery that laser-living tissue (cells) interactions have significant biomedical applications and can be used to perform precise surgical procedures of 'water-like' tissues (such as the eye). When the focus is located within transparent biological cells and tissues, nonlinear absorption processes initiate a laser induced optical breakdown. The threshold for breakdown is defined by a certain critical free electron density. An in depth understanding of these processes orientated our theoretical research to the development of rate equations describing electron density growth in a transparent biological media exposed to a femtosecond laser pulse. In order to provide an accurate theoretical model and to predict damage occurrence, we took into account the losses through diffusion of electrons out of the focal volume, cascade ionization and the model of photoionization based on the standard Keldysh and ADK theory. Keywords: laser-induced breakdown, avalanche process, Keldysh theory. 1. Introduction The advent of high-power lasers opened the door for a wide range of laser application [1, 2, 3]. The effect known as the breakdown is a very important topic due to its role in laser applications. Breakdown is an effect which can be produced by high electric field strengths. This means that after a spark the medium becomes electrically conducting. Laser-induced breakdown (LIB) can occur in any media: solid, liquid, or gas. -
Mixtures Comment on What You Observe in This Photograph
Elements Compounds Mixtures Comment on what you observe in this photograph. How do the sweets in this photograph model the idea of elements, compounds and mixtures? Elements, Compounds & Mixtures By the end of this topic students should be able to… • Identify elements, compounds and mixtures. • Define and explain the terms element, compound and mixture. • Give examples of elements, compounds and mixtures. • Describe the similarities and differences between elements, compounds and mixtures. Elements, Compounds & Mixtures How can I classify the different materials in the world around me? Elements, Compounds & Mixtures Elements, Compounds & Mixtures Elements, Compounds & Mixtures Elements, Compounds & Mixtures Elements, Compounds & Mixtures Elements, Compounds & Mixtures • What other classification systems do scientists use? • One example is the classification of plants and animals in biology. Elements, Compounds & Mixtures Could I have a brief introduction to elements, compounds and mixtures? Elements, Compounds & Mixtures • Iron and sulfur are both chemical elements. • A mixture of iron and sulfur can be separated by a magnet because iron can be magnetised but sulfur cannot. Elements, Compounds & Mixtures Duration 10 seconds. Duration • Iron and sulfur are both chemical elements. • A mixture of iron and sulfur can be separated by a magnet because iron can be magnetised but sulfur cannot. Elements, Compounds & Mixtures • Iron and sulfur react to form the compound iron(II) sulfide. • The compound iron(II) sulfide has new properties that are different to those of iron and sulfur, e.g. iron(II) sulfide is not attracted towards a magnet. Elements, Compounds & Mixtures Duration Duration 25 seconds. • Iron and sulfur react to form the compound iron(II) sulfide. -
Assessment of Portable HAZMAT Sensors for First Responders
The author(s) shown below used Federal funds provided by the U.S. Department of Justice and prepared the following final report: Document Title: Assessment of Portable HAZMAT Sensors for First Responders Author(s): Chad Huffman, Ph.D., Lars Ericson, Ph.D. Document No.: 246708 Date Received: May 2014 Award Number: 2010-IJ-CX-K024 This report has not been published by the U.S. Department of Justice. To provide better customer service, NCJRS has made this Federally- funded grant report available electronically. Opinions or points of view expressed are those of the author(s) and do not necessarily reflect the official position or policies of the U.S. Department of Justice. Assessment of Portable HAZMAT Sensors for First Responders DOJ Office of Justice Programs National Institute of Justice Sensor, Surveillance, and Biometric Technologies (SSBT) Center of Excellence (CoE) March 1, 2012 Submitted by ManTech Advanced Systems International 1000 Technology Drive, Suite 3310 Fairmont, West Virginia 26554 Telephone: (304) 368-4120 Fax: (304) 366-8096 Dr. Chad Huffman, Senior Scientist Dr. Lars Ericson, Director UNCLASSIFIED This project was supported by Award No. 2010-IJ-CX-K024, awarded by the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice. The opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect those of the Department of Justice. This document is a research report submitted to the U.S. Department of Justice. This report has not been published by the Department. Opinions or points of view expressed are those of the author(s) and do not necessarily reflect the official position or policies of the U.S. -
Direct Measurement of Electron Numbers Created at Near-Infrared Laser-Induced Ionization of Various Gases
Direct Measurement of Electron Numbers Created at Near-Infrared Laser-Induced Ionization of Various Gases A. Sharma1, M. N. Slipchenko1, K. A. Rahman1, M. N. Shneider2, and A. Shashurin1 1 Purdue University, West Lafayette, IN, USA 2 Princeton University, Princeton, NJ, USA Abstract In this work, we present temporally resolved measurements of electron numbers created at photoionization of various gases by femtosecond laser pulse at 800 nm wavelength. The experiments were conducted in O2, Xe, Ar, N2, Kr and CO at room temperature and atmospheric pressure. Elastic microwave scattering was used to directly measure the electron numbers. Numbers of electrons in the range 3108 to 31012 electrons were produced by the laser pulse energies 100-700 J. After the laser pulse, plasma decayed on the time scale varied from 1 to 40 ns depending on the gas type and governed by two competing processes, namely, the creation of new electrons from ionization of the metastable atoms and loss of the electrons due to dissociative recombination and attachment to oxygen. Introduction Broad research history of the laser-induced plasmas is related to studies of various nonlinear effects at laser beam propagation such as laser pulse filamentation, laser beam collapse, self-trapping, dispersion, modulation instability, pulse splitting etc.1,2,3,4,5 These effects are various manifestations of the combined action of focusing Kerr nonlinearity (optical Kerr effect) and defocusing nonlinearity due to plasmas. Nowadays laser-induced plasmas find very wide application for plasma-assisted combustion, combustion diagnostics, laser-induced breakdown spectroscopy etc. 5 Conventional techniques for diagnostics of laser-induced plasmas pose detrimental 16 17 - limitations. -
Photoionization
DLJSRF/R 1 fh ~ · DARESBURY SYNCHROTRON RADIATION LECTURE NOTE SERIES No.1 PHOTOIONIZATION by C. Bottcher Science Research Council DARESBURY LABORATORY Daresbury, Warrington, WA4 4AD DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or 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 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. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. © SCIENCE RESEARCH COUNCIL 1974 Enquiries about copyright and reproduction should be addressed to : The Librarian, Daresbury Laboratory, Daresbury, Warrington, WA44AD. IMPORTANT The SRC does not accept any responsibility for loss or damage arising from the use of information contained in any of its reports or in any communication about its tests or investigations. Printed by McCorquodale Printers Ltd., NAwton-IA-Willow,;. M ersey side. DARESBURY SYNCHROTRON RADIATION LECTURE NOTE SERIES No.1 PHOTOIONIZATION C. Bottcher Department of Theoretical Physics University of Manchester Notes on a series of lectures given at Daresbury Laboratory, November 1973 Science Research Council DARESBURY LABORATORY 1974 iWASlER FOREWORD These lectures were given in November 1973 to experimental physicists using the Synchrotron Radiation Facility at Daresbury. -
Photoionization and Excitation of Free Variable Size Van Der Waals Clusters in the Inner Shell Regime
Photoionization and Excitation of Free Variable Size van der Waals Clusters in the Inner Shell Regime Dissertation zur Erlangung des naturwissenschaftlichen Doktorgrades der Bayerischen Julius-Maximilians-Universit¨at Wurzburg¨ vorgelegt von Ioana Lavinia Bradeanu aus Bucharest Wurzburg¨ 2005 Eingereicht am: bei der Fakult¨at fur¨ Chemie und Pharmazie 1. Gutachter: 2. Gutachter: der Dissertation 1. Prufer:¨ 2. Prufer:¨ 3. Prufer:¨ des Offentlichen¨ Promotionskolloquiums Tag der mundlichen¨ Prufung:¨ Doktorurkunde ausgeh¨andigt am: Abstract Photoionization from core levels provides element-specific information on the electronic structure of atoms, molecules, and condensed matter. Post-collision interaction (PCI) is investigated in free, variable size krypton and argon clusters near the Kr 3d- and Ar 2p-ionization energies. Photoionization of free Van der Waals clusters is reported using zero kinetic energy (ZEKE) photoelectron spectroscopy in the Ar 2p, Ne 1s, Kr 3d and N 1s excitation regime. ZEKE photoelectron spectroscopy is used as an experimental technique for investigating the core ionization process as a function of cluster size. It is found that the asymmetry, which is a consequence of PCI, is characteristically smaller for clusters than for isolated atoms. Moreover, there is less asymmetry for bulk-sites than for surface-sites in variable size rare gas clusters. The emission of ultraviolet fluorescence from variable size argon clusters is investigated in the Ar 2p-excitation regime (240–270 eV). The results are assigned in terms of plausi- ble relaxation processes occurring in the 2p-excitation regime. This implies that charge separation mechanisms are active, which occur after electronic relaxation of the core hole. Besides electron impact ionization within clusters caused by Auger electrons, the inter- atomic Coulombic decay (ICD) mechanism appears to be a plausible way to rationalize the experimental findings. -
Time-Discretized Extreme and Vacuum Ultraviolet Spectroscopy of Spark
Journal of Physics D: Applied Physics PAPER Related content - Photoionization capable, extreme and Time-discretized extreme and vacuum ultraviolet vacuum ultraviolet emission in developing low temperature plasmas in air J Stephens, A Fierro, S Beeson et al. spectroscopy of spark discharges in air, N2 and O2 - A nanosecond surface dielectric barrier discharge at elevated pressures: time- To cite this article: D Trienekens et al 2016 J. Phys. D: Appl. Phys. 49 035201 resolved electric field and efficiency of initiation of combustion I N Kosarev, V I Khorunzhenko, E I Mintoussov et al. - Optical emission spectroscopy study in the View the article online for updates and enhancements. VUV–VIS regimes of a developing low- temperature plasma in nitrogen gas A Fierro, G Laity and A Neuber Recent citations - Guided ionization waves: The physics of repeatability XinPei Lu and Kostya (Ken) Ostrikov - Practical considerations for modeling streamer discharges in air with radiation transport J Stephens et al - Photoionization capable, extreme and vacuum ultraviolet emission in developing low temperature plasmas in air J Stephens et al This content was downloaded from IP address 129.118.3.25 on 05/09/2018 at 18:26 IOP Journal of Physics D: Applied Physics Journal of Physics D: Applied Physics J. Phys. D: Appl. Phys. J. Phys. D: Appl. Phys. 49 (2016) 035201 (5pp) doi:10.1088/0022-3727/49/3/035201 49 Time-discretized extreme and vacuum 2016 ultraviolet spectroscopy of spark © 2016 IOP Publishing Ltd discharges in air, N2 and O2 JPAPBE D Trienekens1,2, -
Time-Resolved Resonance Raman Spectroscopy: Exploring Reactive Intermediates
focal point review SANGRAM KESHARI SAHOO AND SIVA UMAPATHY DEPARTMENT OF INORGANIC AND PHYSICAL CHEMISTRY INDIAN INSTITUTE OF SCIENCE BANGALORE -560012, INDIA ANTHONY W. PARKER CENTRAL LASER FACILITY RESEARCH COMPLEX AT HARWELL SCIENCE &TECHNOLOGY FACILITIES COUNCIL RUTHERFORD APPLETON LABORATORY HARWELL OXFORD DIDCOT OXFORDSHIRE, UK OX11 0QX Time-Resolved Resonance Raman Spectroscopy: Exploring Reactive Intermediates The study of reaction mechanisms involves technique. The simultaneous advances in con- efficient spectrometers, and high speed, highly systematic investigations of the correlation temporary time-resolved Raman spectroscopic sensitive multichannel detectors able to collect between structure, reactivity, and time. The techniques and computational methods have a complete spectrum. This review article will challenge is to be able to observe the chemical done much towards visualizing molecular provide a brief chronological development of changes undergone by reactants as they change fingerprint snapshots of the reactive interme- the experimental setup and demonstrate how into products via one or several intermediates diates in the microsecond to femtosecond time experimentalists have conquered numerous such as electronic excited states (singlet and domain. Raman spectroscopy and its sensitive challenges to obtain background-free (remov- triplet), radicals, radical ions, carbocations, counterpart resonance Raman spectroscopy ing fluorescence), intense, and highly spectrally resolved Raman spectra in the nanosecond to carbanions, carbenes, nitrenes, nitrinium ions, have been well proven as means for determin- microsecond (ns–ls) and picosecond (ps) time etc. The vast array of intermediates and ing molecular structure, chemical bonding, domains and, perhaps surprisingly, laid the timescales means there is no single ‘‘do-it-all’’ reactivity, and dynamics of short-lived inter- mediates in solution phase and are advanta- foundations for new techniques such as spatial- geous in comparison to commonly used time- ly offset Raman spectroscopy. -
Carbon Monoxide Interacting with Free-Electron-Laser Pulses
Carbon monoxide interacting with free-electron-laser pulses H. I. B. Banks Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom A. Hadjipittas Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom A. Emmanouilidou Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom Abstract. We study the interaction of a heteronuclear diatomic molecule, carbon monoxide, with a free-electron laser (FEL) pulse. We compute the ion yields and the intermediate states by which the ion yields are populated. We do so using rate equations, computing all relevant molecular and atomic photoionisation cross-sections and Auger rates. We find that the charge distribution of the carbon and oxygen ion yields differ. By varying the photon energy, we demonstrate how to control higher- charged states being populated mostly by carbon or oxygen. Moreover, we identify the differences in the resulting ion yields and pathways populating these yields between a homonuclear molecule, molecular nitrogen, and a heteronuclear molecule, carbon monoxide, interacting with an FEL pulse. These two molecules have similar electronic structure. We also identify the proportion of each ion yield which accesses a two-site double-core-hole state and tailor pulse parameters to maximise this proportion. PACS numbers: 33.80.Rv, 34.80.Gs, 42.50.Hz arXiv:2004.11641v1 [physics.atom-ph] 24 Apr 2020 Submitted to: J. Phys. B: At. Mol. Opt. Phys. Carbon monoxide interacting with free-electron-laser pulses 2 1. Introduction X-ray free-electron lasers (XFELs) [1{3] have introduced new tools and techniques for the investigation and imaging of atoms and molecules [4, 5]. -
Some Basic Concepts
Topics SI units Protons, electrons and neutrons Elements and allotropes States of matter Atomic number 1 Isotopes Relative atomic mass The mole Some basic Gas laws The periodic table concepts Radicals and ions Molecules and compounds Solution concentration Stoichiometry Oxidation and reduction Basic nomenclature 1.1 What is chemistry and why is it important? Matter, be it animal, vegetable or mineral, is composed of chemical elements or combinations thereof. Over a hundred elements are known, although not all are abundant by any means. The vast majority of these elements occur naturally, but some, such as technetium and curium, are artificial. Chemistry is involved with the understanding of the properties of the elements, how they interact with one another, and how the combination of these elements gives compounds that may undergo chemical changes to generate new compounds. Life has evolved systems that depend on carbon as a fundamental element; carbon, hydrogen, nitrogen and oxygen are particularly important in biological systems. A true understanding of biology and molecular biology must be based upon a full knowledge of the structures, properties and reactivities of the molecular components of life. This basic knowledge comes from the study of chemistry. The line between physical and chemical sciences is also a narrow one. Take, for example, the rapidly expanding field of superconducting materials – compounds that possess negligible resistance to the flow of electrons. Typically, this property persists only at very low temperatures but if the super- " conducting materials are to find general application, they must operate at Superconductors: ambient temperatures. Although a physicist may make the conductivity meas- see Box 9.4 urements, it is the preparation and study of the chemical composition of the materials that drive the basic research area. -
Counting the Electrons in a Multiphoton Ionization by Elastic Scattering of Microwaves Received: 10 November 2017 A
www.nature.com/scientificreports OPEN Counting the electrons in a multiphoton ionization by elastic scattering of microwaves Received: 10 November 2017 A. Sharma1, M. N. Slipchenko 2, M. N. Shneider3, X. Wang1, K. A. Rahman2 & A. Shashurin1 Accepted: 31 January 2018 Multiphoton ionization (MPI) is a fundamental frst step in high-energy laser-matter interaction and Published: xx xx xxxx is important for understanding the mechanism of plasma formation. With the discovery of MPI more than 50 years ago, there were numerous attempts to determine the basic physical constants of this process in direct experiments, namely photoionization rates and cross-sections of the MPI; however, no reliable data was available until now, and the spread in the literature values often reaches 2–3 orders of magnitude. This is due to the inability to conduct absolute measurements of plasma electron numbers generated by MPI, which leads to uncertainties and, sometimes, contradictions between MPI cross-section values utilized by diferent researchers across the feld. Here, we report the frst direct measurement of absolute plasma electron numbers generated at MPI of air, and subsequently we precisely determine the ionization rate and cross-section of eight-photon ionization of oxygen −130 −8 16 −1 molecule by 800 nm photons σ8 = (3.3 ± 0.3)×10 W m s . The method, based on the absolute measurement of the electron number created by MPI using elastic scattering of microwaves of the plasma volume in Rayleigh regime, establishes a general approach to directly measure and tabulate basic constants of the MPI process for various gases and photon energies.