Nuclear Quadrupole Effects and Electronic Structure of Molecules in the Solid State
TL;DR: In this paper, measured nuclear quadrupole effects in solids are discussed, compared with nuclear quadrurupole coupling in gases, and correlated to some extent with molecular structure in the solid state.
Abstract: Measured nuclear quadrupole effects in solids are discussed, compared with nuclear quadrupole coupling in gases, and correlated to some extent with molecular structure in the solid state. The iodine crystal affords a good example of intermolecular interactions in the solid state. In this crystal, nuclear quadrupole effects combined with crystallographic information show two intermolecular covalent bonds per atom, each of about 9 percent importance.
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TL;DR: In this article, the measurements of lattice parameters versus pressure made in this laboratory were discussed, primarily, the measurements were made by measuring the lattice parameter of a "marker" along with those of the substance studied.
Abstract: Publisher Summary This chapter discusses, primarily, the measurements of lattice parameters versus pressure made in this laboratory. The apparatus used permits a rather large range of pressure. (When studying a single cubic metal of low compressibility such as Ag, Nb, or Mo where one or two lines suffice, pressures of 550 kbar or more have, on occasion, been obtained. For substances where more lines are necessary, or for mixtures of substances, the range is more limited.) Some of the other methods of measurement permit more accuracy in the low-pressure region. There are no primary pressure standards in the very high pressure range. Pressures are established in this work by measuring the lattice parameter of a “marker” along with those of the substance studied. Commonly used markers include cubic metals such as Al, Ag, Nb, Mo, and Pd, where shock-wave densities corrected to room temperature have been shown to be internally consistent. Salts such as NaCl, MgO, NaF, and LiF that have been studied using these metallic markers have been utilized themselves to measure pressure. Markers are selected which have “windows” (spaces with no lines) in regions where the sample have prominent lines. Also, more compressible markers are used to establish more accurate pressures in the low-pressure region.
136 citations
TL;DR: The radio frequency and microwave spectrum of Ar35ClF has been measured by molecular beam electric resonance spectroscopy as mentioned in this paper, and the atomic arrangement is Ar-Cl-F and the vibrationally averaged argon-chlorine distances are 3.3301(1) and 3.3290(1), respectively.
Abstract: The radio‐frequency and microwave spectrum of Ar35ClF has been measured by molecular beam electric resonance spectroscopy. The molecular constants are: Ar35ClF¯Ar37ClF¯B1327.113(5)MHz1319.650(5)MHzDJ4.66(20)kHz4.72(20)kHzμa1.053(3)DeqQa−140.869(15)MHz−111.053(15)MHz The atomic arrangement is Ar–Cl–F and the vibrationally averaged argon‐chlorine distances are 3.3301(1) and 3.3290(1) A in Ar35ClF and Ar37ClF, respectively. The Ar–ClF bond stretching frequency is 47 cm−1. From the value of eqQa the equilibrium structure is linear with an angle bending frequency of 41 cm−1. The linear structure is striking evidence against the validity of an additive pair potential for an atom and a diatomic molecule. The observed structure is well predicted by Walsh's rule for triatomic molecules.
124 citations
01 Jan 1974
TL;DR: In this paper, the authors proposed a method to solve the problem of protein-protein interactions at the Bell Laboratories of the Harvard University Department of Chemistry, Harvard University; Bell Laboratories, Boston, Massachusetts
Abstract: Author Institution: Department of Chemistry, Harvard University; Bell Laboratories, Harvard University
120 citations
TL;DR: In this paper, the nuclear spin energy levels for different relative magnitudes of quadrupole interaction and external magnetic field were derived for low frequency molecular rotation detection by means of the quadrupoles spectra.
Abstract: Recent experiments have demonstrated the feasibility of observing nuclear electric quadrupole interactions of widely varying magnitudes in solids. While these effects can often be observed in powdered samples, the most complete information is obtainable from the Zeeman pattern of a single crystal. To facilitate interpretation of these experiments, the nuclear spin energy levels are derived for different relative magnitudes of quadrupole interaction and external magnetic field. Besides the knowledge of the gradient of the electric field tensor, in principle, low frequency molecular rotation should be detectable by means of the quadrupole spectra.
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TL;DR: In this article, it was shown that this variation of electric field is usually simply related to the molecular electronic structure, being primarily dependent on the way in which valence electrons fill the lowest energy p-type orbits.
Abstract: Nuclear quadrupole coupling constants in molecules depend on the nuclear quadrupole moments and the variation in electrostatic field at the nucleus. It is shown that this variation of electric field is usually simply related to the molecular electronic structure, being primarily dependent on the way in which valence electrons fill the lowest‐energy p‐type orbits. Structural information which can consequently be obtained from known quadrupole coupling constants is discussed. Hybridization of the normal covalent bonds of N, Cl, and As with at least 15 percent s character is clearly shown. The alkali halides appear to be almost purely ionic; the quadrupole coupling data allow no more than 3 percent covalent character. In addition to molecular structure, some nuclear quadrupole moments are approximately evaluated by use of the theory developed here.
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96 citations
TL;DR: In this paper, the authors present a list of the most important parts of the gleiche Vorzeichen and the Vorzeichniss Gleiche Gr6Be, including the following:
Abstract: Der K e r n des I r t9 t h a t n i t grofler YVahrscheinlichkeit ebenfal ls die D r e h i m p u l s q u a n t e n z a h I I = ~ } ; der W e r t I = 89 k a n n m i t Sicherhei t ausgesch lossen werden. Die m a g n e t i s c h e n K e r n m o m e n t e u n d die e lek t r i schen K e r n q u a d r u p o l m o m e n t e beider I so tope bes i tzen das gleiche Vorzeichen nnd, w e n n ]nan I = ~ fiir das Iso top Ir t91 zug runde legt, auch a n n g h e r n d gleiche Gr6Be.
23 citations
TL;DR: The crystal structure of chlorine at −185°C was determined with the X-ray goniometer as discussed by the authors, and a tetragonal lattice with a = 8.12 A; density 2.09 with 8 molecules per unit cell.
9 citations