| 1. |
- Engelbrektsson, Nils, et al.
(författare)
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The basic features of thermodynamics
- 2021
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Ingår i: Monatshefte für Chemie. - : Springer Science and Business Media LLC. - 0026-9247 .- 1434-4475. ; 152:12, s. 1437-1490
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Forskningsöversikt (refereegranskat)abstract
- More than 100 years ago a Swedish schoolteacher Nils Engelbrektsson could theoretically derive the thermodynamic equation of state, which is universally valid. His colleague, a Swedish schoolteacher Karl Franzén had experimentally verified his inferences and could prove their validity. About hundred years of fierce struggle to persuade the colleagues do finally bring the desiderated victory to Nils and Karl: their trains of thoughts do deserve our careful looking at them. That is just the main idea behind the translation at hand
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| 2. |
- Engström, Olof, 1943
(författare)
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Compensation effects at electron traps in semiconductors
- 2013
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Ingår i: Monatshefte für Chemie. - : Springer Science and Business Media LLC. - 0026-9247 .- 1434-4475. ; 144:1, s. 73-82
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Tidskriftsartikel (refereegranskat)abstract
- The basic qualities for fulfilling the Meyer-Neldel rule (MNR) for thermal electron emission from semiconductor traps are investigated. A trap model including vibronic properties is used with varying entropy arising from the change in elasticity of the ionic part of the trap potential when an electron transition takes place. This gives rise to a system where the compensation effect originates from the increasing entropy change as a function of the enthalpy supply needed for the transition process in concord with Yelon-Movaghar theory. The entropy increase connects to a decrease in the activation energy for electron capture, which amplifies the compensation effect for MNR manifestation. By comparing with experimental data, the result achieved from the model clarifies the experimental observation of class partitioning for centers in GaAs, obeying the MNR. Furthermore, it is demonstrated that traps at metal-oxide-silicon interfaces, with the same properties as bulk traps following the MNR, give rise to capture cross-sections steeply increasing with the Gibbs free energy involved in carrier emission, as found by experiment.
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| 3. |
- Kleiziene, Neringa, et al.
(författare)
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Cyclization of nitrospirobenzopyrans to bridged benzoxazepino[3,2-a]indoles
- 2006
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Ingår i: Monatshefte fur Chemie. - : Springer Science and Business Media LLC. - 1434-4475. ; 137:8, s. 1109-1117
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Tidskriftsartikel (refereegranskat)abstract
- Condensation of 1-substituted 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones with 5-nitrosalicylaldehyde afforded 1'-[(N-monosubstituted carbamoyl)methyl]indoline nitrospirobenzopyrans. Treatment of the latter with strong base led to the formation of a mixture of cis/trans-5a,13-methano-1,3-benzoxazepino[3,2-a]indoles. Results of semiempirical calculations gave evidence that such a transformation of nitrospirobenzopyrans to bicyclic indole derivatives could proceed via a single transition state, where the negatively charged carbon atom attacks the vinylic double bond of the spiropyran system.
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| 4. |
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| 5. |
- Larsson, Ragnar
(författare)
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Concluding remarks on the theory of selective energy transfer and exemplification on a zeolite kinetics study
- 2013
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Ingår i: Monatshefte fur Chemie. - : Springer Science and Business Media LLC. - 1434-4475. ; 144:1, s. 21-28
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Forskningsöversikt (refereegranskat)abstract
- Some 30 years ago it was suggested that catalytic reactions that showed a 'compensation' effect were activated through a vibrational resonance between that one vibrational mode of the reactant that led to reaction and a comparable vibration mode of the catalyst system that represented the energy input. The isokinetic effect can be calculated from this model, in some cases within less than 1 % from the experimental values. The application of the selective energy transfer model to various kinetic investigations provides some rules: (1) The resonance interaction can occur between the quantum of the catalyst vibration and the quantum of the reactant vibration in a ratio of small integers. (2) The activation energy is built up by a certain number of vibrational quanta relating to the critical vibration. (3) The isokinetic temperature can be expressed as a function of the wavenumber of the catalyst vibrator and the wavenumber of the reactant vibrator. (4) The isokinetic data can be used to establish reaction mechanisms. (5) One can also extract the anharmonicity constant of the critical vibration from the data. One observation is that the reacting molecule is not markedly adsorbed, whereas, of course, the remaining molecules may be strongly adsorbed.
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| 6. |
- Lutzenkirchen, Johannes, et al.
(författare)
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Speciation and equilibria in the H+-Al3+ - polyacrylic acid system
- 2018
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Ingår i: Monatshefte fuer Chemie. - : Springer Science and Business Media LLC. - 0026-9247 .- 1434-4475. ; 149:2, s. 423-429
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Tidskriftsartikel (refereegranskat)abstract
- Equilibria between Al3+ and the polyelectrolyte polyacrylic acid (PAA) were studied in 0.1 M NaCl medium at 25 A degrees C (M = mol dm(-3)). The measurements were performed as precise potentiometric titrations in which OH- was in most cases generated coulometrically. The total concentration of Al(III) and PAA varied within the limits 6.23 x 10(-5)-2.01 x 10(-4) M and 7.20 x 10(-4)-1.12 x 10(-3) M, resp., with a 4-18 fold excess of ligand. The value of - log{[H+]/mol dm(-3)} varied between 3 and 5-7, the upper limit set by drifting EMF potentials caused by the onset of a precipitation reaction. The constant capacitance model was utilized to model the experimental data. With the objective of finding a model as simple as possible that gives an acceptable fit to data, the two species AlPAA(2+) and Al(OH)(2)PAA are postulated. The polyelectrolyte effect resulting in pH-dependent formation constants is demonstrated. Furthermore a comparison between the stability constant of the 1:1 complexes of Al3+ with acrylate(-) and PAA(-), respectively, shows the logK value of the latter to be five units higher and is ascribed to particular properties of the polyelectrolyte.
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| 7. |
- Norrehed, Sara, 1982-, et al.
(författare)
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Formation of persistent organic diradicals from N,N'-diphenyl-3,7- diazacyclooctanes
- 2019
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Ingår i: Monatshefte fuer Chemie. - Vienna : Springer. - 0026-9247 .- 1434-4475. ; 150:1, s. 77-84
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Tidskriftsartikel (refereegranskat)abstract
- N,N'-Diphenyl-3,7-diazacyclooctane and structurally related N,N'-diphenylbispidine derivatives react with silver(I) ions in a high-yielding C–C coupling reaction to produce dication–diradical species, with the silver ions serving a double function both as template and as an oxidant. The resulting bis(benzidino)phane derivatives are persistent organic radicals, stable for several months in solution as well as in the solid state, at room temperature and above, as well as being exposed to the atmosphere. The molecular structure features a double-decker cyclophane motif, stabilized by intramolecular π-dimerization of two delocalized benzidinium radical segments. Intermolecular π-dimers are formed in the solid state.
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| 8. |
- Saxena, Surendra, et al.
(författare)
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An alternative, environmentally friendly production process for refractory metal carbides and syngas using methane reduction of the oxide ores
- 2018
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Ingår i: Monatshefte fuer Chemie. - : SPRINGER WIEN. - 0026-9247 .- 1434-4475. ; 149:2, s. 411-422
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Tidskriftsartikel (refereegranskat)abstract
- A potential, environmentally friendly production process for refractory metal carbides is investigated whereby methane is used as the reducing agent for many oxides. Using the most recently available thermodynamic data, the optimum conditions for production of binary and ternary carbides, together with hydrogen-rich gases, have been calculated. Our thermodynamic analysis indicates that methane reduction of the oxides is both economic and helpful in reducing carbon emissions. The investigations show that hot syngas from one reactor may be re-used as input to other reactors to minimize the use of energy in carbide production.
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| 9. |
- Starikov, Evgeni B.
(författare)
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'Entropy is anthropomorphic': does this lead to interpretational devalorisation of entropy-enthalpy compensation?
- 2013
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Ingår i: Monatshefte für Chemie. - : Springer Science and Business Media LLC. - 0026-9247 .- 1434-4475. ; 144:1, s. 97-102
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Tidskriftsartikel (refereegranskat)abstract
- It is presently well recognised that the concept of entropy can be formulated in many different ways-and this is definitely dependent on the problem to be solved. Does this fact really mean that the entropy-enthalpy compensation underlying physically/chemically valid iso-kinetic, iso-selective, iso-equilibrium relationships immediately loses its interpretational value? By invoking the well forgotten (and sometimes even simply unknown!) work by G.A. Linhart, we would like to demonstrate that in effect entropy's anthropomorphicity opens interesting interpretational opportunities.
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| 10. |
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