Thermodynamics and Electrochemistry of Simple Ions in Ammonia

Schindewolf, U.

doi:10.1002/bbpc.19820861004

Cited by 16 publications

(5 citation statements)

References 27 publications

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“…A value of −1259 kJ/mol for the proton's absolute ammonation enthalpy, exceeding the above estimate in magnitude by 36 kJ/mol, results from combining Jolly's water → ammonia transfer enthalpy of −109kJ/mol with the proton's absolute hydration value of Tissandier et al of −1150 kJ/mol, but the transfer result relies on older thermodynamic data . Schindewolf provides an independent estimate of −1265 kJ/mol for the absolute standard enthalpy of ammonation of the proton at −40 °C. This estimate also relies on older thermodynamic data .…”

Section: Application Of the Cluster Pair Correlation Scheme To Ammoniamentioning

confidence: 99%

A New Cluster Pair Method of Determining Absolute Single Ion Solvation Energies Demonstrated in Water and Applied to Ammonia

2002

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A new method of determining standard absolute solvation energies (enthalpies and Gibbs free energies) for individual ions is presented. This method originated from the cluster pair based approximation used in earlier work [Tissandier et al., J. Phys. Chem. A 1998, 102, 7787] and is called the cluster pair correlation scheme. Unlike the earlier approximation, the new scheme makes analysis possible in solvent systems for which bulk ion-solvation data are complemented by cluster ion data, either experimental or theoretical, for clusters containing only a single solvent molecule. The correlation scheme features linear plots of half the difference between standard conventional cluster solvation energies for anions and cations containing equal numbers of solvent molecules in the cluster vs their bulk counterparts. All of the correlation lines should intersect at a point whose ordinate defines the unknown shift between the conventional and absolute energy scales, the standard absolute energy of formation of the proton. The results obtained using this correlation scheme to analyze the available cluster ion data for water are in substantial agreement with the results reported earlier using the cluster pair based approximation. Preliminary values for the standard absolute enthalpy and Gibbs free energy of ammonation of the proton are obtained when the cluster pair correlation scheme is applied to ammonia, and a clear indication is obtained of what additional data are needed to improve these preliminary estimates.

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Section: Application Of the Cluster Pair Correlation Scheme To Ammoniamentioning

confidence: 99%

A New Cluster Pair Method of Determining Absolute Single Ion Solvation Energies Demonstrated in Water and Applied to Ammonia

2002

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“…Thermodynamic data demonstrate that the recombination of the solvated electron with the ammonium cation is highly endergonic [3] such that the predominant recombination channel is the reaction with the dipole under formation of amide anions. However, in the three-body 05027-p.2 system, the interactions are still dominated by the Coulomb attraction between the electron and NH 4 + .…”

Section: Resultsmentioning

confidence: 99%

Femtosecond two-photon ionization of fluid NH₃at 9.3 eV

Urbanek

Dahmen

Torres-Alacan

et al. 2013

EPJ Web of Conferences

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Abstract. Liquid and supercritical ammonia (NH 3 ) is photo-ionized at an energy of 9.3 eV with 100-fs duration pulses at a wavelength of 266 nm. The ionization involves two photons and generates fully solvated electrons via the conduction band of the solvent within the time resolution of the experiment. The dynamics of their ensuing geminate recombination is followed in real time with femtosecond near-infrared (IR) probe pulses. The recombination mechanism can be understood as an ion-pair mediated reaction. The electron survival probability is found to be in quantitative agreement with the classical Onsager theory for the initial recombination of ions.

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“…must be dismissed because the charge recombination is known to be highly endergonic 105 and, hence, very slow. In a concerted mechanism, the transfer of the electron and the hopping of the proton occur simultaneously in which case we must speak of a proton-coupled back electron transfer (PCBET).…”

Section: Methodsmentioning

confidence: 99%

Below-Band-Gap Ionization of Liquid-to-Supercritical Ammonia: Geminate Recombination via Proton-Coupled Back Electron Transfer

Urbanek

Vöhringer

2013

J. Phys. Chem. B

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Femtosecond multiphoton ionization experiments have been conducted on ammonia over a wide range of temperature (225 K ≤ T ≤ 490 K) and density (0.18 g/cm(3) ≤ ρ ≤ 0.7 g/cm(3)), thereby covering the liquid and supercritical phases. The experiments were carried out with excitation pulses having a wavelength of 400 nm, and the ionization was found to involve two photons. Therefore, the total ionization energy in this study corresponds to 6.2 eV, which is roughly 2 eV below the valence-to-conduction band gap of the fluid. The ionization generates solvated electrons, which have been detected through their characteristic near-infrared resonance, and must be facilitated through a coupling to nuclear degrees of freedom of the liquid. The recombination of the solvated electron with the geminate fragments was found to obey predominantly single-exponential kinetics with time constants between 500 fs and 1 ps. Only a very minor fraction of the photogenerated electrons is able to escape from the geminate recombination. The results indicate that the majority of electrons are injected into suitable trapping sites located between the first and second solvation shells of the initially ionized ammonia molecules. Such configurations can be considered as instantly reactive and facilitate an ultrafast barrierless electron annihilation. This process is found to exhibit a pronounced kinetic isotope effect, which indicates that the electronic decay is accompanied by the transfer of a proton. The sequence of ionization and recombination events can therefore be described appropriately as a proton-coupled electron transfer (PCET) followed by a proton-coupled back electron transfer (PCBET).

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Thermodynamics and Electrochemistry of Simple Ions in Ammonia

Cited by 16 publications

References 27 publications

A New Cluster Pair Method of Determining Absolute Single Ion Solvation Energies Demonstrated in Water and Applied to Ammonia

A New Cluster Pair Method of Determining Absolute Single Ion Solvation Energies Demonstrated in Water and Applied to Ammonia

Femtosecond two-photon ionization of fluid NH₃at 9.3 eV

Below-Band-Gap Ionization of Liquid-to-Supercritical Ammonia: Geminate Recombination via Proton-Coupled Back Electron Transfer

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Thermodynamics and Electrochemistry of Simple Ions in Ammonia

Cited by 16 publications

References 27 publications

A New Cluster Pair Method of Determining Absolute Single Ion Solvation Energies Demonstrated in Water and Applied to Ammonia

A New Cluster Pair Method of Determining Absolute Single Ion Solvation Energies Demonstrated in Water and Applied to Ammonia

Femtosecond two-photon ionization of fluid NH3at 9.3 eV

Below-Band-Gap Ionization of Liquid-to-Supercritical Ammonia: Geminate Recombination via Proton-Coupled Back Electron Transfer

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Femtosecond two-photon ionization of fluid NH₃at 9.3 eV