Deuterium and Shift Calculation

Deuterium and Shift Calculation
Author:
Publisher: Springer Science & Business Media
Total Pages: 269
Release: 2012-12-06
Genre: Science
ISBN: 3642759327

In 1931 Vrey, Brickwedde, and Murphy discovered the hydrogen isotope deuterium. The isotopic enrichment was found to arise from the fact that the electrolysis oflight water is faster than of heavy water [1,2]. This success showed that although different isotopes of an element behave identically from a chemical standpoint the different isotopic masses nevertheless lead to both isotope effects on equilibrium as well as on rate constants of chemical reactions. Soon, ratios of equilibrium constants of isotopic reactions were called "equilibrium isotope effects" (EIE), ratios of isotopic rate constants "kinetic isotope effects" (KIE). Isotope effects have been found to be especially large for those elements which are directly involved in bond breaking and bond formation during the reaction studied [3]. Such effects are, therefore, referred to as "primary". Isotopic substitution in atomic sites which maintain all chemical bonds with their neighbors during the reaction of interest leads then only to smaller "secondary" isotope effects. Because of the unique mass relation between the different hydrogen isotopes hydrogen/deuterium isotope effects are particularly large and have attracted most attention. The largest contributions to these effects arise from changes in the vibrational frequencies of the reactants. The theory of equilibrium isotope effects has been founded by Vrey [4] and Bigeleisen [5,6] and has widely been accepted [3].

Deuterium and Shift Calculation

Deuterium and Shift Calculation
Author:
Publisher: Springer
Total Pages: 263
Release: 1990-12-19
Genre: Science
ISBN: 9783540529491

In 1931 Vrey, Brickwedde, and Murphy discovered the hydrogen isotope deuterium. The isotopic enrichment was found to arise from the fact that the electrolysis oflight water is faster than of heavy water [1,2]. This success showed that although different isotopes of an element behave identically from a chemical standpoint the different isotopic masses nevertheless lead to both isotope effects on equilibrium as well as on rate constants of chemical reactions. Soon, ratios of equilibrium constants of isotopic reactions were called "equilibrium isotope effects" (EIE), ratios of isotopic rate constants "kinetic isotope effects" (KIE). Isotope effects have been found to be especially large for those elements which are directly involved in bond breaking and bond formation during the reaction studied [3]. Such effects are, therefore, referred to as "primary". Isotopic substitution in atomic sites which maintain all chemical bonds with their neighbors during the reaction of interest leads then only to smaller "secondary" isotope effects. Because of the unique mass relation between the different hydrogen isotopes hydrogen/deuterium isotope effects are particularly large and have attracted most attention. The largest contributions to these effects arise from changes in the vibrational frequencies of the reactants. The theory of equilibrium isotope effects has been founded by Vrey [4] and Bigeleisen [5,6] and has widely been accepted [3].

Spectroscopy and Computation of Hydrogen-Bonded Systems

Spectroscopy and Computation of Hydrogen-Bonded Systems
Author: Marek J. Wójcik
Publisher: John Wiley & Sons
Total Pages: 548
Release: 2022-12-13
Genre: Science
ISBN: 3527834907

Spectroscopy and Computation of Hydrogen-Bonded Systems Comprehensive spectroscopic view of the state-of the-art in theoretical and experimental hydrogen bonding research Spectroscopy and Computation of Hydrogen-Bonded Systems includes diverse research efforts spanning the frontiers of hydrogen bonding as revealed through state-of-the-art spectroscopic and computational methods, covering a broad range of experimental and theoretical methodologies used to investigate and understand hydrogen bonding. The work explores the key quantitative relationships between fundamental vibrational frequencies and hydrogen-bond length/strength and provides an extensive reference for the advancement of scientific knowledge on hydrogen-bonded systems. Theoretical models of vibrational landscapes in hydrogen-bonded systems, as well as kindred studies designed to interpret intricate spectral features in gaseous complexes, liquids, crystals, ices, polymers, and nanocomposites, serve to elucidate the provenance of spectroscopic findings. Results of experimental and theoretical studies on multidimensional proton transfer are also presented. Edited by two highly qualified researchers in the field, sample topics covered in Spectroscopy and Computation of Hydrogen-Bonded Systems include: Quantum-mechanical treatments of tunneling-mediated pathways and molecular-dynamics simulations of structure and dynamics in hydrogen-bonded systems Mechanisms of multiple proton-transfer pathways in hydrogen-bonded clusters and modern spectroscopic tools with synergistic quantum-chemical analyses Mechanistic investigations of deuterium kinetic isotope effects, ab initio path integral methods, and molecular-dynamics simulations Key relationships that exist between fundamental vibrational frequencies and hydrogen-bond length/strength Analogous spectroscopic and semi-empirical computational techniques examining larger hydrogen-bonded systems Reflecting the polymorphic nature of hydrogen bonding and bringing together the latest experimental and computational work in the field, Spectroscopy and Computation of Hydrogen-Bonded Systems is an essential resource for chemists and other scientists involved in projects or research that intersects with the topics covered within.

A Primer of NMR Theory with Calculations in Mathematica

A Primer of NMR Theory with Calculations in Mathematica
Author: Alan J. Benesi
Publisher: John Wiley & Sons
Total Pages: 250
Release: 2015-05-19
Genre: Science
ISBN: 1119052157

Präsentiert die NMR-Theorie in Verbindung mit Unterlagen aus Mathematica-Kursen. - Bietet kurze, Schwerpunktkapitel mit kurzen Erläuterungen zu definierten Themen und konzentriert sich dabei auf mathematische Beschreibungen. - Präsentiert prägnant wichtige Erkenntnisse aus der Quantenmechanik, die bei der Prognose und Simulation von Ergebnissen aus NMR-Versuchen einfach angewendet werden können. - Enthält Mathematica-Anleitungen, die die Theorie in Form von Text, Grafik, Ton und Berechnungsbeispielen praktisch umsetzen. - Geht auf bewährte Methoden des Autors aus über 25 Jahren Lehrerfahrung zurück. Die Unterlagen erläutern präzise die Theorie und bieten nützliche Berechnungsvorlagen für NMR-Forscher.