DOCSLIB.ORG

Electron Solvation and the Unique Liquid Structure of a Mixed‐Amine

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electron Solvation and the Unique Liquid Structure of a Mixed‐Amine Angewandte Communications Chemie International Edition:DOI:10.1002/anie.201609192 Liquid Phases German Edition:DOI:10.1002/ange.201609192 Electron Solvation and the Unique Liquid Structure of aMixed-Amine Expanded Metal:The Saturated Li–NH3–MeNH2 System Andrew G. Seel, Helen Swan, Daniel T. Bowron, Jonathan C. Wasse,Thomas Weller, Peter P. Edwards,Christopher A. Howard, and Neal T. Skipper* Abstract: Metal–amine solutions provideaunique arena in the solutions are electrolytic, whereby the metal valence which to study electrons in solution, and to tune the electron electrons have been ionized into solution and exist as solvated density from the extremes of electrolytic through to true electrons propagating between solvent cavities.[3] Increasing metallic behavior.The existence and structure of anew class of the concentration results in metallization in the liquid phase, concentrated metal-amine liquid, Li–NH3–MeNH2,ispre- which for the Li NH3 system occurs at amere 4mol%metal [2] À sented in which the mixed solvent produces anovel type of (MPM). Interestingly at lower temperatures,below TC = electron solvation and delocalization that is fundamentally 210 K, the point of the Mott-type metal–insulator transition different from either of the constituent systems.NMR, ESR, (MIT) is obscured by apronounced liquid–liquid phase and neutron diffraction allowthe environment of the solvated separation.[2] This illustrates that the localized and delocalized electron and liquid structure to be precisely interrogated. electron states do not readily co-exist, which is dramatically Unexpectedly it was found that the solution is truly homoge- manifested by the fact that the more concentrated metallic neous and metallic.Equally surprising was the observation of solution floats above the dilute electrolytic phase for T< [2,4] strong longer-range order in this mixed solvent system. This is Tc. Above 8MPM the solutions do not exhibit phase despite the heterogeneity of the cation solvation, and it is separation, appearing golden up to the concentration limit of [5] [6,7] concluded that the solvated electron itself acts as astructural 20 MPM, theexpanded metal Li(NH3)4. Theconcentra- template.This is aquite remarkable observation, given that the tion and temperature dependence of this liquid–liquid phase liquid is metallic. separation has been mapped through multi-element NMR spectroscopy.[8] Alkali metals demonstrate an exceptional solubility in NH3, Along with metal concentration, chemical tunability of yielding intensely colored conducting solutions that have the electronic properties of these systems can be achieved by [1,2] fascinated chemists since the time of Sir Humphry Davy. varying the amine.Lithium will also dissolve in MeNH2 to Varying the concentration of metal in these liquids dramat- yield asystem whereby solvated electrons transition to [3,9–12] ically alters the electronic,magnetic,and structural properties ametallic state. TheMIT in Li–MeNH2 occurs at of the solutions,and enables us to experimentally determine 15 MPM, anotably higher concentration than in Li–NH3. the manner in which liquid systems accommodate excess No liquid–liquid phase separation has been detected across electron density.Atalow concentration of metal/electrons, the full concentration range of Li–MeNH2,and the solution remains adeep blue,albeit with ametallic luster. The 1 1 conductivity of liquid Li(MeNH2)4 is 400 WÀ cmÀ (compared 1 1 [*] Dr.A.G.Seel, Prof. P. P. Edwards to 15000 WÀ cmÀ in Li(NH3)4), which is close to Motts Department of Chemistry,Inorganic Chemistry Laboratory minimum conductivity limit, demonstrating that the Li– UniversityofOxford MeNH2 system lies just on the metallic side of the MIT. South Parks Road, Oxford, OX1 3QR (UK) Thediffering metallic properties of Li–NH3 and Li– Dr.H.Swan, Dr.J.C.Wasse, Dr.T.Weller,Dr. C. A. Howard, MeNH2 are also reflected in their distinct liquid struc- Prof. N. T. Skipper [13,14] Department of Physics and Astronomy,University College London tures. All metallic metal amines share the trait of being [13–16] Gower Street, London, WC1E 6BT (UK) highly structured liquids, with distinct M(solv)–M(solv) E-mail:[email protected] correlations.Inboth Li–NH3 and Li–MeNH2 solutions,Liis Dr.H.Swan found to be four-coordinate,which has subsequently been National Nuclear Laboratory,Culham Science Centre found to be the case in the gas phase,[17–19] and through Abingdon, OX14 3DB (UK) computational investigation.[1,19–21] Thevolumetric expansion Dr.D.T.Bowron of these liquid metals across their insulator–metal transition is ISIS Spallation Neutron Source also accompanied by the appearance of void spaces,which is STFC RutherfordAppleton Laboratory presumably linked to the conduction electron density.InLi– Chilton, Didcot, OX11 0QX (UK) NH3 these voids take the form of channels between Li(NH3)4 Supportinginformation for this article can be found under: units,[13] whereas in Li(MeNH ) the voids are spatially http://dx.doi.org/10.1002/anie.201609192. 2 4 isolated.[14] This is concordant with magnetic measurements 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. that suggest electronic conduction in Li(MeNH ) is via rapid KGaA. This is an open access article under the terms of the Creative 2 4 Commons AttributionLicense, which permits use, distribution and migration of electrons between these polaronic voids,which [22,23] reproduction in any medium, provided the original work is properly begin to localize in the solid state. cited. Angew.Chem. Int.Ed. 2017, 56,1561 –1565 2017 The Authors. Published by Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim 1561 Angewandte Communications Chemie Thequestion then is how amixture of Li(NH3)4 and Li(MeNH2)4 will behave.Surprisingly,perhaps,these mixed amine solutions have only previously been studied by optical absorption towards the limit of infinite dilution.[24] Herein we report the first studies of the liquid structure of Li-NH3- MeNH2 in the concentrated regime at 20 MPM, an empirical stoichiometry of Li(NH3)2(MeNH2)2.Wenote that after equilibration these solutions appear to the eye as homoge- nous red/bronze liquids (Figure 1), which upon dilution 7 Figure 1. Topleft: Li NMR for 20 MPM Li(NH3)2(MeNH2)2 Topright: Temperaturedependence of the 7Li Knight shift, Bottom left:Homog- enization of the 20 MPM system showing initial phase separation (left) and homogenous liquid (right). Bottom right:ESR line shape for 20 MPM Li(NH3)2(MeNH2)2. Figure 2. Top: Experimentaltotal structure factors for 20 MPM 6Li– nat demonstrate apronounced liquid–liquid phase separation ND3–CD3ND2 and Li–ND3–CD3ND2 solutions. Middle:First-order Li whereby the lustrous phase floats above adeep-blue solution. differencestructure factor.Bottom:Corresponding Li partial pair correlation. We have observed this phase separation across avery large concentration range of Li, from 2–19 MPM. As confirmation of the homogeneity at 20 MPM, Figure 1shows that only 7 asingle feature is witnessed in the corresponding Li NMR Table 1: Isotopic substitutions in samples of 20 MPM Li–NH3–MeNH2. spectrum. This has proven to be an extremely sensitive Sample Li NH3 MeNH2 [8] indication of homogeneity in previous metal–amine studies. nat 7 A Li ND3 CD3ND2 Interestingly,the Li peak appears at higher ppm than both nat [8,12,25] B Li NH3 CD3NH2 Li(NH3)4 and Li(MeNH2)4, suggesting ahigher conduc- nat C Li [NH3 :ND3][CD3NH2 :CD3ND2] tion electron spin-density at the Li nucleus (or indeed larger nat D Li ND3 CH3ND2 nat molar spin susceptibility) in the mixed amine than in either of E Li ND3 [CD3ND2 :CH3ND2] 7 nat the parent amines.The temperature dependence of the Li F Li NH3 CH3NH2 [8] nat Knight shift and the Dysonian lineshape of the ESR are also G Li [NH3 :ND3][CD3ND2 :CH3NH2 :CD3NH2 :CH3ND2] 7 indicative of ahomogeneous metallic system.[22,26,27] H Li ND3 CD3ND2 Neutron diffraction is auniquely powerful method for determining the liquid structure of metal amines,allowing for anumber of isotopically distinct samples to be measured the homogeneity of the 20 MPM solution. Thepre-peak is (defined in the Experimental Section below). Figure 2 astructural feature witnessed in solvated-electron systems as presents an example fit to an experimental total structure they transition to the metallic state,and arises owing to strong factor, F(Q), from samples Aand HinTable 1. Also shown is intermediate range ordering in the liquid.[13–15] Integration of the difference spectrum [F6 (Q) Fnat (Q)] and its Fourier the principal peak in the DG (r)distribution corresponds to Li À Li Li transform, the Li-centered total pair correlation function, the coordination number of Li, and is consistent with 1 DGLi(r). Thesingle principal peak at 1.75 À ,and impor- approximately 4solvent molecules,asreported previously 1 [13,14] tantly the existence of asharp pre-peak at 0.97 À ,attest to for other Li–RNH2 systems. 1562 www.angewandte.org 2017 The Authors. Published by Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim Angew.Chem. Int.Ed. 2017, 56,1561 –1565 Angewandte Communications Chemie To determine the spatial arrangement of lithium and Importantly,the EPSR model also reveals the statistical amine species in the system, the empirical potential structure distribution of ammonia and methylamine molecules in the + refinement (EPSR) technique was invoked to produce [Li(NH3)n(MeNH2)m] tetrahedral complexes (Supporting astructural model that was refined simultaneously to all the Information, Figure S2). This distribution shows that for isotopically unique experimental F(Q)functions (Table 1).[28] around 40%ofcations (n,m)is(2,2), for around 50%itis Figure 3shows the EPSR fits to the experimental data, (1,3) or (3,1), and for the remaining 10%itis(0,4) or (4,0). with the EPSR model fitting well the experimentally obtained Thecation solvation is therefore significantly heterogeneous, partial structure factors.The corresponding real-space distri- and it is all the more surprising that we observe asharp bution of solvent molecules around the lithium ions is given in diffraction pre-peak in our data, indicative of longer-range order in the liquid.
Load more

Recommended publications
  • Gas-Phase Electrochemistry: Measuring Absolute Potentials and Investigating Ion and Electron Hydration*
    Pure Appl. Chem., Vol. 83, No. 12, pp. 2129–2151, 2011. doi:10.1351/PAC-CON-11-08-15 © 2011 IUPAC, Publication date (Web): 7 October 2011 Gas-phase electrochemistry: Measuring absolute potentials and investigating ion and electron hydration* William A. Donald1,‡ and Evan R. Williams2 1School of Chemistry, Bio21 Institute of Molecular Science and Biotechnology, and ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, University of Melbourne, Melbourne, Victoria, Australia; 2Department of Chemistry, University of California, Berkeley, CA, USA Abstract: In solution, half-cell potentials and ion solvation energies (or enthalpies) are meas- ured relative to other values, thus establishing ladders of thermochemical values that are ref- erenced to the potential of the standard hydrogen electrode (SHE) and the proton hydration energy (or enthalpy), respectively, which are both arbitrarily assigned a value of 0. In this focused review article, we describe three routes for obtaining absolute solution-phase half- cell potentials using ion nanocalorimetry, in which the energy resulting from electron capture (EC) by large hydrated ions in the gas phase are obtained from the number of water mole- cules lost from the reduced precursor cluster, which was developed by the Williams group at the University of California, Berkeley. Recent ion nanocalorimetry methods for investigating ion and electron hydration and for obtaining the absolute hydration enthalpy of the electron are discussed. From these methods, an absolute electrochemical scale and ion solvation scale can be established from experimental measurements without any models. Keywords: absolute potentials; clusters; electrochemistry; electron capture dissociation; elec- tron transfer; gaseous state; hydrated ions; hydration; ion nanocalorimetry; solvation; thermo chemistry.
    [Show full text]
  • Periodic Trends and the S-Block Elements”, Chapter 21 from the Book Principles of General Chemistry (Index.Html) (V
    This is “Periodic Trends and the s-Block Elements”, chapter 21 from the book Principles of General Chemistry (index.html) (v. 1.0M). This book is licensed under a Creative Commons by-nc-sa 3.0 (http://creativecommons.org/licenses/by-nc-sa/ 3.0/) license. See the license for more details, but that basically means you can share this book as long as you credit the author (but see below), don't make money from it, and do make it available to everyone else under the same terms. This content was accessible as of December 29, 2012, and it was downloaded then by Andy Schmitz (http://lardbucket.org) in an effort to preserve the availability of this book. Normally, the author and publisher would be credited here. However, the publisher has asked for the customary Creative Commons attribution to the original publisher, authors, title, and book URI to be removed. Additionally, per the publisher's request, their name has been removed in some passages. More information is available on this project's attribution page (http://2012books.lardbucket.org/attribution.html?utm_source=header). For more information on the source of this book, or why it is available for free, please see the project's home page (http://2012books.lardbucket.org/). You can browse or download additional books there. i Chapter 21 Periodic Trends and the s-Block Elements In previous chapters, we used the principles of chemical bonding, thermodynamics, and kinetics to provide a conceptual framework for understanding the chemistry of the elements. Beginning in Chapter 21 "Periodic Trends and the ", we use the periodic table to guide our discussion of the properties and reactions of the elements and the synthesis and uses of some of their commercially important compounds.
    [Show full text]
  • Coordination Chemistry in Liquid Ammonia and Phosphorous Donor Solvents
    Coordination Chemistry in Liquid Ammonia and Phosphorous Donor Solvents Kersti B. Nilsson Faculty of Natural Resources and Agricultural Sciences Department of Chemistry Uppsala Doctoral thesis Swedish University of Agricultural Sciences Uppsala 2005 Acta Universitatis Agriculturae Sueciae 2005: number 21 ISSN 1652-6880 ISBN 91-576-7020-x © 2005 Kersti B. Nilsson, Uppsala Tryck: SLU Service/Repro, Uppsala 2005 Abstract Nilsson, K. B., Coordination chemistry in liquid ammonia and phosphorous donor solvents. Doctor’s dissertation. ISSN 1652-6880, ISBN 91-576-7020-x The thesis summarizes and discusses the results from coordination chemistry studies of solvated d10 metal and copper(II) ions, and mercury(II) halide complexes in the strong electron-pair donor solvents liquid and aqueous ammonia, trialkyl phosphite, triphenyl phosphite and trialkylphosphine. The main techniques used are EXAFS, metal NMR and vibrational spectroscopy, and crystallography. Four crystal structures containing ammonia solvated metal ions have been determined. Questions addressed concern whether any changes in the preferential coordination numbers and geometries occur when these metal ions are transferred from aqueous ammonia to liquid ammonia solution, or to phosphorous donor solvents. Liquid ammonia and trialkyl phosphites are found to possess similar electron-pair donor properties, DS=56 for both, while trialkylphosphines are known to be even stronger electron-pair donors. The studies reveal that the ammonia-solvated d10 metal ions obtain very different configurations in liquid ammonia, with gold(I) being linear, copper(I) and silver(I) trigonal, zinc(II) and mercury(II) tetrahedral, and cadmium(II), indium(III) and thallium(III) octahedral. The ammonia-solvated copper(I) and silver(I) ions are linear in aqueous ammonia solution because of the lower ammonia activity, as the third ammine complexes are very weak in aqueous systems.
    [Show full text]
  • Synthesis of K2se Solar Cell Dopant in Liquid NH3 by Solvated Electron T Transfer to Elemental Selenium ⁎ D
    Electrochemistry Communications 93 (2018) 44–48 Contents lists available at ScienceDirect Electrochemistry Communications journal homepage: www.elsevier.com/locate/elecom Synthesis of K2Se solar cell dopant in liquid NH3 by solvated electron T transfer to elemental selenium ⁎ D. Colombaraa,b, , A.-M. Gonçalvesb, A. Etcheberryb a Université du Luxembourg, Physics and Materials Science Research Unit – 41, Rue du Brill, L-4422 Belvaux, Luxembourg b Université de Versailles, Institut Lavoisier de Versailles – 45, Avenue des États Unis, 78000 Versailles, France ARTICLE INFO ABSTRACT Keywords: This study explores the rich chemistry of elemental selenium reduction to monoselenide anions. The simplest Solvated electron possible homogeneous electron transfer occurs with free electrons, which is only possible in plasmas; however, Liquid ammonia alkali metals in liquid ammonia can supply unbound electrons at much lower temperatures, allowing in situ Microelectrode analysis. Here, solvated electrons reduce elemental selenium to K2Se, a compound relevant for alkali metal Alkali metal selenide extrinsic doping doping of Cu(In,Ga)Se solar cell material. It is proposed that the reaction follows pseudo first-order kinetics Chalcopyrite 2 with an inner-sphere or outer-sphere oxidation semi reaction mechanism depending on the concentration of sol- Copper indium gallium diselenide vated electrons. 1. Introduction the 1930s as powerful reducing agents in both organic and inorganic synthesis [20–23]. It was first proposed by Kraus [24, 25] and has Alkali metals play a crucial role in the world's most efficient solar subsequently been accepted that alkali metals dissociate at least par- cell devices based on the chalcopyrite Cu(In,Ga)Se2 (CIGS) semi- tially into alkali cations and solvated electrons under the action of li- conductor, where they act as extrinsic dopants [1–3].
    [Show full text]
  • Deuterium Atom Pickup in Srq Solvated by Ammonia
    7 May 1999 Chemical Physics Letters 304Ž. 1999 350±356 Cluster size specific chemistry: deuterium atom pickup in Srq solvated by ammonia David C. Sperry, James I. Lee, James M. Farrar ) Department of Chemistry, UniÕersity of Rochester, Rochester, NY 14627-0216, USA Received 14 January 1999; in final form 25 February 1999 Abstract We report on recent experimental evidence for deuterium atom pickup in metal ion±polar solvent clusters. Mass spectral q analysis shows the existence of species that correspond to the empirical formula SrŽ. ND3 nx D , where x is as large as 4 for clusters in the size range ns10±15. Photodissociation spectra of several of these clusters indicate that their structures are q very different from the purely ammoniated analogs, SrŽ. ND3 n . Based on deuterium scavenging data and absorption q spectra, we propose the formation of SrD to account for one of the excess deuteriums, and the existence of solvated ND4 to account for additional deuterium atoms in the cluster. q 1999 Elsevier Science B.V. All rights reserved. 1. Introduction mine structure and reactivity. Johnson and collabora- torswx 4,5 reported on reactions of neutral electron y Clusters are a unique form of matter, intermediate scavengers withŽ. H2 On , arguing that an electron to isolated gas-phase molecules and condensed me- transfer mechanism explains the formation of sol- dia. These small aggregates of molecules and atoms vated charge transfer products. are free to exhibit properties distinct from either the Spectroscopic techniques have been used exten- gas or condensed phases. Much attention has been sively to understand the structures of solutions as focused on determining the structure and electronic modeled by cluster systemswx 6±12 .
    [Show full text]
  • Relaxation Dynamics and Genuine Properties of the Solvated Electron
    Relaxation Dynamics and Genuine Properties of the Solvated Electron in Neutral Water Clusters Thomas E. Gartmann,¥ Loren Ban,¥ Bruce L. Yoder, Sebastian Hartweg, Egor Chasovskikh, and Ruth Signorell* Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093, Zürich, Switzerland ¥ These authors contributed equally to this work. * E-mail: [email protected] Abstract: We have investigated the solvation dynamics and the genuine binding energy and photoemission anisotropy of the solvated electron in neutral water clusters with a combination of time-resolved photoelectron velocity map imaging and electron scattering simulations. The dynamics was probed with a UV probe pulse following above-band-gap excitation with a EUV pump pulse. The solvation dynamics is completed within about 2 ps. Only a single band is observed in the spectra, with no indication for isomers with distinct binding energies. Data analysis with an electron scattering model reveals a genuine binding energy in the range of 3.55-3.85 eV and a genuine anisotropy parameter in the range of 0.51-0.66 for the ground-state hydrated electron. All these observations coincide with those for liquid bulk, which is rather unexpected for an average cluster size of 300 molecules. 1 The broad attention that solvated electrons in their ground and excited states have attracted over many decades can be attributed to them being among the simplest quantum solutes as well as to their important role in a wide range of fields. Many studies have focused on excess electrons in water and anion water clusters1-37 (and refs.
    [Show full text]
  • Inventory of World-Wide PCB Destruction Capacity
    UNITED NATIONS ENVIRONMENT PROGRAMME United Nations Inventory of World-wide PCB Destruction Capacity First Issue December 1998 Prepared by UNEP Chemicals in co-operation with the Secretariat of the Basel Convention (SBC) INTER-ORGANIZATION PROGRAMME FOR THE SOUND MANAGEMENT OF CHEMICALS IOMC _________________________________________________________________________________________________________ A cooperative agreement among UNEP, ILO, FAO, WHO, UNIDO, UNITAR and OECD The publication is intended to serve as a first guide on available PCB destruction facilities. While the information provided is believed to be accurate, UNEP disclaim any responsibility for the possible inaccuracies or omissions and consequences which may flow from them. Neither UNEP nor any individual involved in the preparation of this report shall be liable for any injury, loss, damage or prejudice of any kind that may be caused by any persons who have acted based on their understanding of the information contained in this publication. The designation employed and the presentation material in this report do not imply any expression of any opinion whatsoever on the part of the United Nations or UNEP concerning the legal status of any country, territory, city or area or any of its authorities, or concerning any delimitation of its frontiers or boundaries. This publication was developed under contract with AEA Technology Environment. Any views expressed in the document do not necessarily reflect the views of UNEP. The photo on the cover page is taken from the UNEP/SBC pilot project in Côte d'Ivoire, 1997. This publication is produced within the framework of the Inter-Organization Programme for the Sound Management of Chemicals (IOMC) Material in this publication may be freely quoted or reprinted, but acknowledgement is requested together with a reference to the document number.
    [Show full text]
  • Main Attributes of Nuclides Presented in This Book
    Appendix A Main Attributes of Nuclides Presented in This Book Data given in TableA.1 can be used to determine the various decay energies for the specific radioactive decay examples as well as for the nuclear activation examples presented in this book. M stands for the nuclear rest mass; M stands for the atomic rest mass. The data were obtained from the NIST and are based on CODATA 2010 as follows: 1. Data for atomic masses M are given in atomic mass constants u and were obtained from the NIST at: (http://www.physics.nist.gov/pml/data/comp.cfm). 2. Rest mass of proton mp, neutron mn, electron me, and of the atomic mass constant u are from the NIST (http://www.physics.nist.gov/cuu/constants/index. html) as follows: −27 2 mp = 1.672 621 777×10 kg = 1.007 276 467 u = 938.272 046 MeV/c (A.1) −27 2 mn = 1.674 927 351×10 kg = 1.008 664 916 u = 939.565 379 MeV/c (A.2) −31 −4 2 me = 9.109 382 91×10 kg = 5.485 799 095×10 u = 0.510 998 928 MeV/c (A.3) − 1u= 1.660 538 922×10 27 kg = 931.494 060 MeV/c2 (A.4) 3. For a given nuclide, its nuclear rest energy was determined by subtracting the 2 rest energy of all atomic orbital electrons (Zmec ) from the atomic rest energy M(u)c2 as follows 2 2 2 Mc = M(u)c − Zmec = M(u) × 931.494 060 MeV/u − Z × 0.510 999 MeV.
    [Show full text]
  • The Quantum Chemistry of Loosely-Bound Electrons
    CHAPTER 8 The Quantum Chemistry of Loosely-Bound Electrons John M. Herbert Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA INTRODUCTION AND OVERVIEW What Is a Loosely-Bound Electron? By some measure, the title of this chapter could have been “The quantum chemistry of weakly-bound anions,” because much of it will focus on how to describe the weak binding of an “extra” electron to a stable, neutral molecule using electronic structure theory. Electron binding energies in such cases may be quite small, typically less than the largest atomic electron affinities (EAs)1 (3.4 eV for F and 3.6 eV for Cl), and even less than 0.1 eV in some cases. Unlike the case where a neutral molecule, M, is ionized, an electron separated from the anion M− does not experience an attractive −1∕r potential at large separations,2,3 but rather only charge–dipole and or higher order charge–multipole interactions. Cases where the electron affinity of M is ≲ 0.5 eV are the signature of a short-range valence potential that is weakly attractive at best, such that electron binding in M− results primarily from long-range electron–molecule, charge–multipole interactions. In such cases, one expects to find an unpaired electron− inM that is radially diffuse, much more so than in F− or Cl−, for example. It is in this sense that the odd electron in M− is “loosely-bound.” Moreover, the preceding discussion assumes that M− is bound at all, but in fact we will also consider cases in which the electron Reviews in Computational Chemistry, Volume 28, First Edition.
    [Show full text]
  • Nanocalorimetry in Mass Spectrometry: a Route to Understanding Ion And
    Nanocalorimetry in mass spectrometry: A route SPECIAL FEATURE to understanding ion and electron solvation William A. Donald, Ryan D. Leib, Jeremy T. O’Brien, Anne I. S. Holm*, and Evan R. Williams† Department of Chemistry, University of California, Berkeley, CA 94720-1460 Edited by Fred W. McLafferty, Cornell University, Ithaca, NY, and approved May 16, 2008 (Received for review February 15, 2008). A gaseous nanocalorimetry approach is used to investigate effects has been reported. Electron vertical detachment energies Ϫ of hydration and ion identity on the energy resulting from ion– (VDEs) of (H2O)n clusters have been measured for n between electron recombination. Capture of a thermally generated electron 2 and 69 by using photoelectron spectroscopy (15). Based on the by a hydrated multivalent ion results in either loss of a H atom dependence of the solvation energy on cluster size, which accompanied by water loss or exclusively loss of water. The energy proceeds as n1/3, these data extrapolate to a value of 3.3 eV at resulting from electron capture by the precursor is obtained from infinite cluster size. This value is consistent with the photoelec- the extent of water loss. Results for large-size-selected clusters of tric threshold of water obtained from a thermocycle involving 3؉ 2؉ Co(NH3)6(H2O)n and Cu(H2O)n indicate that the ion in the cluster the hydrated electron in ice (3.2 eV) (15) and computational is reduced on electron capture. The trend in the data for values that range from 3 to 4 eV (25), suggesting that a bulk-like < 3؉ Co(NH3)6(H2O)n over the largest sizes (n 50) can be fit to that interior electron state for these clusters was probed.
    [Show full text]
  • Electrical Conductivity Measurements of Lithium-Ammonia Solutions
    Western Michigan University ScholarWorks at WMU Master's Theses Graduate College 8-2003 Electrical Conductivity Measurements of Lithium-Ammonia Solutions Mariana Constantin Barbu Follow this and additional works at: https://scholarworks.wmich.edu/masters_theses Part of the Physics Commons Recommended Citation Barbu, Mariana Constantin, "Electrical Conductivity Measurements of Lithium-Ammonia Solutions" (2003). Master's Theses. 4260. https://scholarworks.wmich.edu/masters_theses/4260 This Masters Thesis-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Master's Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. ELECTRICAL CONDUCTIVITY MEASUREMENTS OF LITHIUM-AMMONIA SOLUTIONS by Mariana Constantin Barbu A Thesis Submitted to the Faculty of The Graduate College In partial fulfillment of the requirements for the Degree of Master of Arts Department of Physics Western Michigan University Kalamazoo, Michigan August 2003 Copyright by Mariana Constantin Barbu 2003 For my Dad ACKNOWLEDGMENTS I would like to give thanks to my advisor, Dr. Clement Bums, for his help and support while working on the project, and forwriting the thesis. I would also like to thank Dr. Lisa Paulius for reviewing my thesis, and providing valuable input. Her help and support were important in my work. I want to express my thanks to Dr. Dean Balderson in my own way. If I could go back in time, I would do things differently. I consider myself lucky having a friendlike Valentina Tobos. Thank you, Valentina for everything. A special thanks goes to Allan Kem, who was always helpfuland nice.
    [Show full text]
  • Dynamics of Excess Electrons in Atomic and Molecular Clusters
    Dynamics of excess electrons in atomic and molecular clusters by Ryan Michael Young A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Chemistry in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Daniel M. Neumark, Chair Professor Stephen R. Leone Professor Robert W. Dibble Fall 2011 Abstract Dynamics of excess electrons in atomic and molecular clusters by Ryan Michael Young Doctor of Philosophy in Chemistry University of California, Berkeley Professor Daniel M. Neumark, Chair Femtosecond time-resolved photoelectron imaging (TRPEI) is applied to the study of excess electrons in clusters as well as to microsolvated anion species. This technique can be used to perform explicit time-resolved as well as one-color (single- or multiphoton) studies on gas phase species. The first part of this dissertation details time-resolved studies done on atomic clusters with an excess electron, the excited-state dynamics of solvated molecular anions, and charge-transfer dynamics to solvent clusters. The second part summarizes various one-color photoelectron imaging studies on tetrahydrofuran clusters with an excess electron or doped with an iodide ion in order to probe the solvent structure of these clusters. Finally, a mixed study is presented exploring the effect of warmer cluster conditions on both the binding energies and relaxation times of excess electrons in water clusters. Time-resolved studies on mercury cluster anions (Hg)n¯ (7 ≤ n ≤ 20) demonstrate the different timescales of electron-phonon and electron-electron scattering in small systems. Low- energy (1.0-1.5 eV) excitation of the excess electron to a higher-lying electronic state decays via a cascade through the conduction band on a 10-40 ps timescale.
    [Show full text]