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1.
Jan E. Åman Ingemar Bengtsson Narit Pidokrajt 《General Relativity and Gravitation》2006,38(8):1305-1315
The Hessian of either the entropy or the energy function can be regarded as a metric on a Gibbs surface. For two parameter families of asymptotically flat black holes in arbitrary dimension one or the other of these metrics are flat, and the state space is a flat wedge. The mathematical reason for this is traced back to the scale invariance of the Einstein–Maxwell equations. The picture of state space that we obtain makes some properties such as the occurence of divergent specific heats transparent.Supported by VR. 相似文献
2.
J rgen Rosenqvist Kristina Axe Staffan Sj berg Per Persson 《Colloids and surfaces. A, Physicochemical and engineering aspects》2003,220(1-3):91-104
The adsorption of the dicarboxylates o-phthalate, maleate, fumarate, malonate, and oxalate (representing ligands with the general composition −O2C---Cn---CO2−; n=0, 1, or 2) on gibbsite were studied by means of quantitative batch adsorption experiments and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The interpretations of ATR-FTIR spectra were aided by comparison with IR spectra of solution species and by results from theoretical frequency calculations. The main objectives of the study were to identify the molecular level bonding mechanisms of the dicarboxylates to gibbsite, and to investigate how these were influenced by the composition and structure of the ligands. Carboxylates with n=2 formed predominantly outer sphere complexes, whereas the importance of inner sphere complexes progressively increased for n=1 and 0. The inner sphere structures were identified as mononuclear chelates with one oxygen from each carboxylate group bonded to Al(III) at the surface. This showed the importance of chelate ring structure for the formation of inner sphere surface complexes, with stabilities of the complexes increasing in the order seven-membered ring less than six-membered ring less than five-membered ring. For ligands with n=2 only small variations in surface speciation were observed as a function of steric factors; irrespective of the relative positions of the carboxylate groups and bulkiness of the ligands outer sphere bonding is the dominating adsorption mode. Adsorption experiments were also conducted with gibbsite particles exhibiting differences in shape and surface roughness. These experiments showed that inner sphere complexes were favored on the less well-developed and more irregular gibbsite particles. 相似文献
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Òscar Rubio-Pons Boris Minaev Oleksandr Loboda Hans Ågren 《Theoretical chemistry accounts》2005,113(1):15-27
The phosphorescence spectrum of p-dichlorobenzene has been calculated using multiconfiguration self-consistent-field wave functions and the quadratic response technique. Attention has been paid to the intensity distribution of the singlet–triplet (3B1u1Ag) transition through a number of vibronic subbands. The second order spin–orbit coupling (SOC) contribution to the spin splitting of the 3B1u (3*) state is found to be almost negligible, and the calculations therefore provide a good estimate for the zero-field splitting (ZFS) parameters based only on the electron spin–spin coupling expectation values. Nuclear quadrupole resonance constants for the different Cl isotopes are also calculated to accomplish the ZFS assignment. The electric dipole activity of the spin sublevels in the triplet–singlet transitions to the ground-state vibrational levels is estimated by calculations of derivatives using distorted geometries which are shifted from the equilibrium position along different vibrational modes. A vibrational analysis of the phosphorescence spectrum, based on the SOC-induced mixing of the singlet and triplet states calculated along different vibrational modes, provides reasonable agreement with experimental data.Acknowledgment O. R.-P. would like to thank the European MOLPROP network for support. The authors thank Alexander Baev for fruitful discussions. This work was supported by the Swedish Royal Academy of Science (KVA). 相似文献
5.
Åse Støg»rd 《Chemical physics letters》1975,36(3):357-360
Ab initio as well as semi-empirical SCF MO calculations are presented for ClCN and ONCl. The relative intensities for Cl Kβ emission in the two molecules were calculated. The calculated spectra from the ab initio wavefunctions are in excellent agreement with experiments. 相似文献
6.
As bio‐inspired chemical model of the oxygen‐evolving complex (OEC) in photosystem II, a new tyrosine‐modified corrole ligand 3 and its high‐valent copper and manganese complexes 3a and 3b were synthesized and characterized. The copper complexes 1a and 2a of corrole 1 and 2 were also prepared for comparison. The emission property indicates that the emission of ligands 2 and 3 is located at 670 nm, but no emission is observed for their metal complexes due to its suppression by the metal center. The electrochemical study shows that 3a might dimerize at the first two reversible oxidations, a behavior which was not observed in the case of 1a and 2a . The corrolato manganese(IV) complex 3b shows one reversible reduction and one quasireversible oxidation at ?0.17 and 0.77 V vs. Ag/Ag+, respectively. 相似文献
7.
High-temperature equilibrium calculations are used to study potential interferences in the determination of aluminium by flameless a.a.s. The conditions for the formation of interfering aluminium compounds like AlO(g), Al2O(g), Al2O3(s), AlOH(g), AlH(g), AlHO2(g), AlS(g), AlN(g), AlN(s) and AlCl(g) have been calculated. The influence of kinetic parameters on the equilibrium calculations for the reactions involving carbon—oxygen and carbon—sulphur has been established by varying the input amount of carbon. The results indicate that even in the nanomole range the presence of elements like H, O, N, Cl and S may cause severe interferences during the atomization step (2300–2900 K) 相似文献
8.
Ideal conditions for the determination of phosphorus by graphite-furnace atomic absorption spectrometry are investigated by the use of high-temperature equilibrium calculations. All reasonable reaction products resulting from the reaction between P, C, O, H, N, Ca and Ar are considered. The calculations show that phosphorus forms the volatile monoxide and dioxide molecules below 1800 K (Po2? 10-13 atm.). At higher temperatures the relative amount of atomic phosphorus is mainly controlled by the equilibrium between monatomic and diatomic phosphorus. The significance of the theoretical ' study was investigated experimentally. The relative amounts of P2 and PO were monitored by molecular absorption using vaporization under isothermal conditions; the interfering effects of Ca, N2, H2, and O2 on the atomic absorption signal for phosphorus were also studied. The sensitivity was greatly dependent on graphite tube conditions as well as the heating rate of the furnace. For CaHPO4 the sensitivity for phosphorus was 4.5 × lO-8 g. If samples were introduced into a preheated tube, this value was improved to 2 × 10-9 g. 相似文献
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