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1.
G. Möller E. Träbert P. H. Heckmann 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1988,9(1):5-14
A grazing-incidence spectrometer for the wavelength range λ≦13 nm has been built and tested with foil-excited fast oxygen ions. The new apparatus has been used to study the variation of the 2s 3p 3 P 1 0 level lifetime in the Be isoelectronic sequence by observation of the intercombination decay to the 2s 2 1 S 0 ground state. The experimental problems are described. The results agree with only some of the theoretical predictions. 相似文献
2.
D. Charalambidis B. H. Feng C. Fotakis 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1989,14(3):223-227
Photoelectron angular distributions have been measured for the three-photon resonant one-photon ionization, (3+1), of Xe via the 7s[1 1/2]0 1 and 8s[1 1/2]0 1 states. The results are in good agreement with the theoretical predictions of Tang and Lambropoulos [13] for the 8s[1 1/2]0 1, but not for the 7s[1 1/2]0 1 state. Furthermore, the results are compared to those which have been obtained by Blazewicz et al. [1] for the three-photon resonant two-photon ionization, (3+2), of Xe via the 6s[1 1/2]0 1 state. 相似文献
3.
E. Träbert 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1986,2(3):213-222
The 3s 23p 2 3 P 1, 2–3s3p 3 5 S 2 0 transitions in Ni14+ and Cu15+ have been identified in beam-foil spectra. The wavelengths have been measured (41.700±0.01 nm/43.998±0.01 nm for Ni14+, 38.76±0.03 nm/41.02±0.02 nm for Cu15+) in delayed spectra. For the first time in this isoelectronic sequence the lifetime of the5 S 2 0 level has been determined (Ni: 33±5 ns, Cu: 22±3 ns). Experimental problems are discussed. The results are compared with theoretical data. 相似文献
4.
Volker Staemmler 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,39(2):121-125
Accurate quantum-chemical ab initio calculations have been performed at the SCF and CEPA (coupled electron pair approximation) levels for the van der Waals interaction in the X 2 Σ + ground state of LiHe. An extended basis set has been used and the counterpoise correction for the basis set superposition error (BSSE) has been applied. The calculated potential energy curve has a very shallow minimum at 11.56 a 0 with a well depth of only 1.49 cm?1. This is too small to allow for a bound vibrational level. The analysis of the results shows that the interaction mainly consists of the Pauli repulsion between Li(1s 22s) and He (1s 2), which is decaying exponentially, and the attractive London dispersion energy. Van der Waals coefficients C6, C8, and C10 have been determined by a least squares fit to the long-range part of the calculated potential curve. 相似文献
5.
P. L. Larkins P. Hannaford 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(4):313-320
Absolute frequencies of hyperfine components of the 230.6 nm (5s 2 1 S 0?5s5p 3 P 1 0 ), 193.6 nm (5s5p 3 P 0 0 ?5s6s 3 S 1), 197.7 nm (5s5p 3 P 1 0 ?5s6s 3 S 1) and 207.9 nm (5s5p 3 P 2 0 ?5s6s 3 S 1) transitions in In II emitted from a hollow-cathode source have been measured using a high-resolution, scanning échelle monochromator. The measured frequencies of these four transitions have been used to determine the energies and hyperfine interaction constants of the 5s5p 3 P 0 0 ,3 P 1 0 ,3 P 2 0 and 5s6s 3 S 1 levels in In II. The hyperfine interaction constants for the dominant isotope115In are found to be: 5s5p 3 P 1 0 A=0.2322(2) cm?1,B=?0.0159(9) cm?1 5s5p 3 P 2 0 A=0.1699(4) cm?1,B= 0.021 (6) cm?1 5s6s 3 S 1 A=0.4022(4) cm?1,B= 0.002 (2) cm?1. The absolute frequency of the very narrow, strongly forbidden In II 236.5 nm (5s 2 1 S 0?5s5p 3 P 0 0 ) transition, which has been proposed as a candidate for a new optical frequency standard, is found to be 42275.986(7) cm?1. 相似文献
6.
J. Kwela 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1994,32(1):35-40
The intensity of the 531.5 nm electric-field-quench radiation has been measured on a thermal beam of neutral Pb atoms in the metastable 6p 2 1 S 0 state. The measurement yields a Stark-mixing amplitude for transition between the 6p 2 1 S 0 and 6p 2 3 P 2 states. Combining this result with available experimental data sets an upper limit for the 6p 7s 3 P 1 → 6p 2 1 S 0 transition probability:A ki <1.79·103 s ?1. Calculations for the 6p 7s → 6p 2 and 6p 8s → 6p 2, as well as transition rates of forbidden lines inside 6p 2 configuration of PbI are presented and compared with existing experimental data. 相似文献
7.
S. Schennach A. Müller O. Uwira J. Haselbauer W. Spies A. Frank M. Wagner R. Becker M. Kleinod E. Jennewein N. Angert P. H. Mokler N. R. Badnell M. S. Pindzola 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1994,30(4):291-306
Dielectronic recombination (DR) of Ar15+(1s 22s) ions was studied in a single-pass merged-beams experiment at the UNILAC (universal linear accelerator) of GSI. Absolute recombination rates and cross sections were measured for electron-ion center-of-mass energies from 0 to 580 eV. A number of Rydberg states formed by DR with 2s → 2p (Δn=0) and 2s → 3? (Δn=1) core excitations and even individual terms in the 1s 23?3?′ configuration could be resolved. Theoretical calculations of DR cross sections are in good overall agreement with the data. In the calculations for Δn=0 transitions, effects of electric fields have to be included to reproduce the magnitude of the measured DR rates at the limit of the 2 p 1/2? and 2 p 3/2? Rydberg series. Discrepancies between theory and experiment are observed at the series limits of the (1s 23?n?′) Rydberg series. 相似文献
8.
E. Träbert R. Hutton I. Martinson 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,5(2):125-131
In delayed spectra of foil-excited beams of Ti, Fe, Ni and Cu ions lines have been observed which are identified with intercombination transitions 3s 2 1 S 0 — 3s 3p 3 P 1 0 , 3s 2 3p 2 P 0 — 3s 3p 2 4 P and 3s 2 3p 2 3 P — 3s 3p 3 5 S 2 0 in magnesiumlike, aluminiumlike and siliconlike spectra, resp. Wavelengths and decay properties have been determined. The results are compared to recent theoretical predictions. 相似文献
9.
E. Laviron 《Journal of Electroanalytical Chemistry》1984,164(2):213-227
The kinetics of the p-benzoquinone/hydroquinone Q/QH2 couple on a platinum electrode are analysed on the basis of the theory presented earlier (E. Laviron, J. Electroanal. Chem., 146 (1983) 15) for the nine-member square scheme when the protonations are assumed to be at equilibrium, using experimental data from the literature. The square scheme is of the NN type. The Tafel plots and the variations of the experimental apparent rate constants between pH 0 and 7 are in good agreement with the theoretical predictions. The heterogeneous rate constants found for the elemental electrochemical steps are as follow: Q Q?, kh3=1/6×10?3 cm s?1; QH.QH?, kh5=0.11 cm s?1; QH+QH., kh2?160 cm s?1; kh4 for the reaction QH2+.QH2 is in the range 0.5–4 cm s?1. Between pH 0 and 7, the reaction sequence during the reduction is, for the most part, successively H+e?H+e?, e?H+H+e?, and e?H+e?H+ (reverse sequence during the oxidation). 相似文献
10.
The reaction kinetics between O2? and C6H5CH2Br has been investigated in N,N′-dimethylformamide by electroanalytical techniques. A mechanism is proposed in which two molecules of the primary electrode product regenerate, via a following chemical reaction, one molecule of the original electroactive species. Furthermore, evidence for a SN2 reaction mechanism between O2? and C6H5CH2Br has been obtained. Second order rate constants resulted to be 11000 M?1s?1 and 3000 M?1s?1at room temperature and 0°C, respectively. The main products of the reaction were found to be benzylalcohol, benzaldehyde, benzene and biphenyl. 相似文献
11.
R. Kau I. D. Petrov V. L. Sukhorukov H. Hotop 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,39(4):267-281
Using high resolution laser photoelectron spectrometry we have determined absolute cross sections σJ 0 J 1 and the electron angular distribution parameter for one photon ionization of metastable Xe*(6s 3 P J0, J 0 = 2, 0) atoms to the resolved Xe+ (2 P J1, J 1 = 3/2, 1/2) ion states at several wavelengths near threshold. For comparison with the present and future experimental data we have calculated partial cross sections and ß-parameters for photoionization of Xe*(6s 3 P J0, J 0 = 2, 0) and of the analogous alkali atom Cs(6s) over the photoelectron energy range (0–5) eV. We have used both a term-dependent Pauli-Fock (PF) approach and a configuration interaction method involving Pauli-Fock atomic orbitals (CIPF). Through the PF method we include relativistic effects on the atomic orbitals; the CIPF method was designed to take into account the important electron correlation effects which are found to be essential for obtaining good agreement between the theoretical and experimental results. 相似文献
12.
《Journal of Inorganic and Nuclear Chemistry》1976,28(5):985-987
The phase diagram of the system (1 − s) Li0·5Ga2·5O4−s CuGa2O4 has been established by quenching, DTA, X-ray diffraction at high temperature and IR spectrometry. The change from the disordered (space group P4332) to the ordered cubic form (space group Fd3m) is made by means of an extensive biphase (0·25 ⩽ s ⩽ 0·52). The thermal stability of copper and mixed gallates has been studied by thermogravimetric analyses. The spectrum of Cu2+ in spinels (0·8–2·5 μ, s ⩾ 0·54) discloses copper on A and B sites. The cation distribution is deduced from neutron diffraction. 相似文献
13.
14.
The kinetics of oxidative addition of CH3I to [Rh(FcCOCHCOCF3)(CO)(PPh3)], where Fc = ferrocenyl and (FcCOCHCOCF3)− = fctfa = ferrocenoylacetonato, have been studied utilizing UV/Vis, IR, 1H and 31P NMR techniques. Three definite sets of reactions involving isomers of at least two distinctly different classes of RhIII-alkyl and two different classes of RhIII-acyl species were observed. Rate constants for this reaction in CHCl3 at 25 °C, applicable to the reaction sequence below, were determined as k1 = 0.00611(1) dm3 mol−1 s−1, k−1 = 0.0005(1) s−1, k3 = 0.00017(2) s−1 and k4 = 0.0000044(1) s−1 while k−3 ? k3 and k−4 ? k4 but both ≠0. The indeterminable equilibrium K2 was fast enough to be maintained during RhI depletion in the first set of reactions and during the RhIIIalkyl2 formation in the second set of reactions. From a 1H and 31P NMR study in CDCl3, Kc1 was found to be 0.68, Kc2 = 2.57, Kc3 = 1.00, Kc4 = 4.56 and Kc5 = 1.65. 相似文献
15.
M. Baumann M. Braun J. Maier 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,6(3):275-278
Radiative lifetimes in the even parity 6s n d 1 D 2 (n=6?13) and 6s n s 1 S 0 (n=8?14) level series of neutral Yb have been measured. In contrast to a monotonicn*3 behaviour which is expected in the absence of configuration interaction a drastic decrease of the lifetime data was observed in the vicinity of multiply excited states. In addition, for certain levels a strong increase of the lifetime values has been found which may be ascribed to destructive interference due to configuration mixing which can also affect the branching ratios of the radiative decay of these levels. 相似文献
16.
The 57Fe Mössbauer effect in two samples (A and B) of [Fe(papt)2] and in its solvates with CHCl3 and C6H6 has been studied between 4.2 and 343 K and clearly indicates a temperature induced high-spin (5T2) ? low-spin (1A1) transition in these compounds [paptH = 2-(2-pyridylamino)-4-(2-pyridyl) thiazole]. At 343 K, sample B shows a doublet with ΔEQ = 2.03 mm s?1 and δIS = +0.87 mm s?1, characteristic of a 5T2 ground state. At 257 K, a second doublet, typical for a 1A1 ground state, is observed and its intensity increases as the transition progresses but levels off below ~ 100 K. At 4.2 K, 83% of the intensity is due to the 1A1 state, and ΔEQ(1A1) = 1.56 mm s?1 and δIS(1A1 = +0.32 mm s?1. In an applied magnetic field, Vzz(1A1) < 0 and η ≈ 0.7 have been determined, whereas for the sT2 ground state, Vzz(sT2) > 0, η ≈ 0.75, and an internal hyperfine field Hn ≈ ?13 kG have been observed. Similar results have been obtained with the other samples.Debye-Waller factors f5T2 and f1A1 were determined from the saturation corrected areas in the Mössbauer spectra, assuming Curie-Weiss dependence of the magnetic susceptibility for the 5T2 and constant υcff for the 1A1 ground state. The temperature dependence of ?In f1A1 closely follows the Debye model with Θ1A1 = 165 K, whereas the same applies to ?ln f5T2 only above ~ 210 K and Θ5T2 = 134 K. The nature of the observed transition is discussed and the data presented are shown to be incompatible with a model based on a Boltzmann distribution between the two states. 相似文献
17.
《The Journal of chemical thermodynamics》2003,35(8):1237-1251
Molar enthalpies of vaporization, ΔlgHm0, of 1-methyl-naphthalene, 1-chloro-napthalene, 2-chloro-naphthalene, 1-bromo-naphthalene, 2-bromo-naphthalene, and 1-iodo-naphthalene, as well as molar enthalpies of sublimation, ΔsgHm0, of 2-chloro-naphthalene and 2-bromo-naphthalene have been obtained from the temperature dependence of the vapor pressure determined with the transpiration method. These values and the correlation gas-chromatography method, based on the Kovat’s index, have been used to determine ΔlgHm0 and ΔsgHm0 of 2-iodo-naphthalene. Results obtained in this work have been compared with those from the literature and found consistent. 相似文献
18.
Three single electron charge transfer redox reactions have been studied using the faradaic rectification method. The kinetic parameters obtained for the ferricyanide-ferrocyanide redox couple are α=0.49, ka0=12×10?2 cm s?1; for the chromic-chromous system α=0.47, ka0=2×10?3 cm s?1 and for the titanic-titanous reaction α=0.49 and kao=6×10?4 cm s?1 at 27°C. 相似文献
19.
J. Carlsson H. Lundberg W. X. Peng A. Persson C. G. Wahlström T. Brage C. Froese Fischer 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1986,3(4):345-351
Using laser spectroscopic techniques the natural radiative lifetimes of 4s 2 n 1 s 2 S and 4s 2 n 2 d 2 D states of neutral gallium have been measured forn 1 = 6 to 11 andn 2 = 4 to 9. These states, as well as previously measured4s 2 np 2 P states, have been investigated theoretically using multi-configuration Hartree-Fock calculations. Oscillator strengths to all lower-lying states have been calculated and theoretical lifetimes of the investigated states evaluated. The2 D sequence is strongly influenced by the 4s4p 2 2 D perturber, and strong cancellation effects in the radiative decay are observed both theoretically and experimentally. 相似文献
20.
G. Möller E. Träbert P. H. Heckmann P. H. Mokler A. E. Livingston 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,18(3):223-229
The experimental access to M1 transition probabilities within thens 2 np k (1 ≦k ≦ 5) ground state configurations of highly ionized atoms is outlined. A test experiment on Xe(45–50)+ yielded first spectra and decay curves of the 2s 2 1 S 0 ? 2s2p 3 P 1 0 intercombination transition in Xe50+ and of M1 transitions within the 2s 2 2p k (1 ≦k ≦ 5) ground configurations. The data compare well only with theoretical predictions which take the Lamb shift into account. Problems and prospects for better measurements are discussed. 相似文献