共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Taniguchi S. Suga S. Shin K. Inoue M. Seki H. Kanzaki 《Solid State Communications》1982,44(1):85-88
Reflectance spectra due to 3d core-levels of Ge have been measured in the photon-energy region from 29 to 38 eV by means of synchrotron radiation. Second-energy-derivative spectra have newly shown pairs of doublet structures with energy separation of the Ge core-level splitting. The observed doublet structures are assigned to the transitions from the and core-levels to the flat regions of the conduction band around the particular symmetry points of Δ6c and L(3c(L6c, L4,5c). 相似文献
2.
The UPS and XPS spectra of Xe adsorbed on clean, O, CO, and Xe covered W(110) surfaces and the UPS spectrum for Kr on clean and O covered W(110) surfaces have been investigated. On clean W, Xe and Kr show a splitting of the and hole states respectively. For Xe the coverage dependence of this splitting was investigated in detail; neither the positions nor the intensity ratio of the substates are coverage dependent for θ ? 0.04, suggesting that splitting is due to differences in the image interaction of the and components. For Xe equal shifts, relative to vacuum, of ~1.0 eV were observed for 5p, 4d, and 3d levels, suggesting that initial state effects are small. Image interaction for Xe and Kr on clean W could best be fitted by assuming an increase, rather than a decrease in the effective hole-image separation from the nominal value, suggesting that the image plane is moved back into the metal by a screening length. For Xe adsorbed on (110), or on virgin- polarization of the intermediate layers was found to contribute significantly to relaxation. Coadsorbed oxygen broadened Xe 5p and Kr 4p peaks. There was an almost linear relation between O 2p UPS intensity at the energies of the various peaks and the amounts of broadening, suggesting that the latter results from resonance neutralization by electrons from the O 2p states. 相似文献
3.
P.L. Lijnse P.J.Th. Zeegers C.Th.J. Alkemade 《Journal of Quantitative Spectroscopy & Radiative Transfer》1973,13(10):1033-1045
Weighted average quenching cross sections for the Rb(52P) doublet by N2 and H2O were determined in flames with temperatures ranging from 1500 to 2500 K by measuring the fluorescence efficiency. The values found are and over the entire temperature range. At a temperature of 1720 K, mixing cross sections were obtained for the same doublet with N2, H2, O2 and H2O molecules. The cross sections found are: , ; , , , . The ratios σ12/σ21 were measured independently and were found to agree with the detailed- balance condition within 3 per cent. A critical comparison of the flame values with previous literature data on N2-cross sections shows that both mixing and quenching cross sections are temperature dependent in the range from 300 to 2500 K. 相似文献
4.
L Nemes 《Journal of Molecular Spectroscopy》1978,72(1):102-123
Medium resolution infrared grating spectra of gaseous ketene, H2CCO were recorded between 1000 and 400 cm?1, both at instrument temperature (40°C) and with cooling (?40°C). Interferometric Fourier spectra were also measured at ?70°C with resolution 0.22 cm?1 between 450 and 330 cm?1. The K structure of the fundamentals ν5, ν6, ν8, and ν9 was assigned. These fundamentals are coupled by a-axis Coriolis interactions. These couplings were analysed on the symmetric top basis for setting up the perturbation matrix and by utilizing the K-dependent Coriolis shifts of levels. A preliminary analysis of the Coriolis intensity anomalies was also undertaken.Band center values from combination differences are and . Synthetic spectra indicate the band origins of ν8 and ν9 to be close to 977.8 and 439.0 cm?1, respectively. Estimates of Coriolis coupling constants obtained from synthetic spectra are , , , and . Approximate ratios of unperturbed vibrational transition moments obtained from spectral simulations are . 相似文献
5.
The emission of Ni2+ ions in MgO, KMgF3, KZnF3 and MgF2 crystals has been investigated. The fine structure on the bands at about 20 000 cm-1 and 13 000 cm-1 has been studied in detail and from this and the excitation spectra these bands are assigned to and transitions respectively. 相似文献
6.
X-ray photoelectron spectroscopy (ESCA) has been used to study the physical adsorption of Xe and the chemisorption of oxygen by W (111). An ultrahigh vacuum ESCA spectrometer has been modified such that thermal desorption behavior from the W (111) crystal can be directly compared with ESCA spectra of the adsorbed species. In addition, since the work function of a W (111) crystal covered with one monolayer of Xe is accurately known from previous work, the binding energy of the adsorbate level can be accurately compared to the gaseous level.When Xe is physisorbed to 1 monolayer the level exhibits a binding energy (relative to the vacuum level) which is 2.1 eV below that found for Xe (g). At lower Xe coverages the shift becomes monotonically greater, approaching 2.6 eV at a Xe coverage of 0.05. This 0.5 eV shift downward is accompanied by an increase of only 0.05 eV in adsorption energy as coverage decreases, and may be partially caused by the presence of ~ 10–20 % of extraneous adsorption sites other than W (111) which adsorb Xe with higher adsorption energy. The adsorption energy of Xe may also be increased by coadsorption of oxygen and the binding energy exhibits a corresponding shift downward as adsorbed oxygen coverage is increased to θo = 0.5. Electronic relaxation processes affecting the final state are dominant factors in determining the magnitude of the chemical shift upon adsorption, in agreement with the predictions of Shirley. The magnitude of the relaxation effect seems to be very sensitive to small changes in Xe adsorption energy. Similar effects have been seen for chemisorption of CO.The adsorption of O2 at 120 K by W (111) yields a single broad O(1s) peak whose line-width decreases with increasing coverage. The final spectra at θo = 1 monolayer are very similar to those obtained at temperatures of 300 K or above on polycrystalline tungsten. 相似文献
7.
Lithium-containing oxide bronzes LixV2?yMyO5-β (M=Mo or W) have been studied in wide range of temperature (25–550°C) and composition (0.22?x?0.47, 0?y?0.25) as prospective ionic-electronic conductors. By coulometric titration tecknique, , and have been found and ordering of the lithium ions within the channel structure LixV2O5-β has been discussed depending on composition and temperature. The chemical diffusion coefficient for lithium D?Li has been measured by potentiometric technique on hot-pressed ceramic samples. The lithium self-diffusion coefficient DLi and partial lithium-ionic conductivity have been calculated. 相似文献
8.
Alkali atoms were scattered with hyperthermal energies from a clean and an oxygen covered (θ ≈ 0.5 ML) W(110) surface. The trapping probability of K and Na atoms on oxygen covered W(110) has been measured as a function of incoming energy (0–30 eV) and incident angle. A considerable enhancement of trapping on the oxygen covered surface compared to a clean surface was observed. At energies above 25 eV there are still K and Na atoms being trapped by the oxygen covered surface. From the temperature dependence of the mean residence time τ of the initially trapped atoms the pre-exponential factor τ0 and the desorption energy Q were derived using the relation: . On clean W(110) we obtained for Li: , Q = (2.78 ± 0.09) eV; for Na: τ0 = (9 ± 3) × 10?14 sec, Q = (2.55 ± 0.04) eV; and for K: τ0 = (4 ± 1) × 10?13 sec, Q = (2.05 ± 0.02) eV. Oxygen covered W(110) gave for Na: τ0 = (7 ±3) × 10?15 sec, Q = (2.88 ± 0.05) eV; and for K: , Q = (2.48 ±0.05) eV. The adsorption on clean W(110) has the features of a supermobile two-dimentional gas; on the oxygen covered W(110) adsorbed atoms have the partition function of a one-dimen-sional gas. The binding of the adatoms to the surface has a highly ionic character in the systems of the present experiment. An estimate is given for the screening length of the non-perfect conductor W(110):ks?1≈ 0.5 Å. 相似文献
9.
The J = 2?1 microwave spectrum of six isotopic species of HSiF3 has been observed and assigned in excited states of five of the six fundamental vibrations. The assignment is based on relative intensities, double resonance experiments, and trial anharmonic force constant calculations. Analysis of the spectra leads to experimental values for five of the constants, all three l-doubling constants qt, one Fermi resonance constant φ233, and one zeta constant .The harmonic force field has been refined to all the available data on vibration wavenumbers, centrifugal distortion constants, and zeta constants. The cubic anharmonic force field has been refined to the data on and qt constants, using two models: a valence force model with two cubic force constants for SiH and SiF stretching, and a more sophisticated model. With the help of these calculations, the following equilibrium structure has been determined: , , ∠HSiF = 110.64(±3)°, 相似文献
10.
11.
Metastable He2 molecules are produced by a dc discharge in a flowing He stream. Laser excitation downstream of the discharge produces excitation spectra for a number of He2 states. LIF spectra are observed for the series for n = 4–9, excepting 5 and the series for n = 5–15. 相似文献
12.
H. Venghaus 《Journal of luminescence》1978,16(3):331-341
Luminescence measurements were performed on high purity epitaxial n-GaAs for various excitation intensities I0 in the range . The luminescence line corresponding to the radiative decay of the shallow donor bound exciton, (D0, X), broadens with increasing I0 and appears as a doublet for , while the two-electron replica of the (D0, X) remains a single narrow line. The doublet structure of the (D0, X) at elevated excitation levels is due to missing luminescence intensity in the center of the line as a consequence of low (D0, X) concentration in a layer extending 1–2 μm from the sample surface into the bulk. The low concentration of (D0, X) is attributed to capture of (D0, X) quanta into surface states, extending to lower energies from the Fermi level fixed by the shallow donors. Comparison of the present results with luminescence spectra obtained by various authors reveals, that unexplained spectral features in the (D0, X) region of n-GaAs reported in the literature are a consequence of high excitation intensity and correspond to the effect reported here. In partly compensated p-GaAs with donor concentrations as given above, the (D0, X) did not transform into a doublet structure even at excitation intensity. 相似文献
13.
J.W. Boldeman A.R. de L. Musgrove B.J. Allen J.A. Harvey R.L. Macklin 《Nuclear Physics A》1976,269(1):31-45
The neutron total and capture cross sections of92,94Zr have been measured at the 80 and 40 m flight stations, respectively, on the Oak Ridge Electron Linear Accelerator (ORELA). Resonance analysis of the total cross sections gave values of s, and strength functions. Strong intermediate structure was observed in the cross section of 92Zr. Significant single particle transitions identified in the p-wave capture cross section indicate the importance of the valence process for both nuclei. It is noted that the intermediate structure in the total cross section leads to enhanced valence effects in the capture cross section. The effects of non statistical E1 transitions following particle-hole annihilation in the compound states were not observed in either the 92Zr or 94Zr capture cross sections as they had been in that for 90Zr. 相似文献
14.
The interaction of oxygen with polycrystalline cobalt surfaces has been studied at 300 K (1 × 10?6 to 1 × 10?5 Torr) using high-resolution (monochromatized) X-ray photoemission. At high exposures (> 100 L nominal) CoO is identified as the product from the nature of the , and valence band spectra. There is no evidence for measurable amounts of Co3O4 or Co2O3. Two O 1s features are observed at both high and low (10L) exposures. The dominant O 1s feature at 529.5 ± 0.2 eV corresponds to the oxide and a minor feature at 531.3 ± 0.2 eV is attributed to non-stoichiometric surface oxygen. Exposure to air produces quite different results, with a dominant O 1s feature at 531.5 ± 0.2 eV and dominant and features centered at 781.3 ± 0.2 eV and 797.1 ± 0.2 eV. These three values are very close to those reported here for bulk Co(OH)2. Ion etching of the air-exposed surface removes this dominant surface product rapidly revealing some oxide and finally metal. 相似文献
15.
The atomic structure of the (112̄0) surface of cobalt has been determined by LEED using six intensity spectra at normal incidence. The surface exhibits the truncated bulk structure with a contraction of the first interlayer spacing by about 8.5% with respect to the bulk value. Quantitative evaluation of the LEED spectra was done using Zanazzi and Jona's and Pendry's r-factors. The minimum averaged r-factors are and . No change of the interatomic distances within the plane could be detected and no rearrangement of the surface structure takes place up to temperatures shortly below the transition temperature. 相似文献
16.
By using an ultra-high vacuum X-ray photoelectron spectrometer designed specifically for surface studies, the surface sensitivity (ratio of surface to volume signal) of the technique was found to be enhanced by approximately one order of magnitude at low angles of electron emission measured from the surface plane. While the ) peak intensity from a clean polycrystalline target of molybdenum was independent of angle, the ) intensity from an adsorbed cesium layer on molybdenum increased and the ) signal from the molybdenum substrate decreased as the angle of emission was decreased. A model is presented to account for the angular dependence and it is proposed that the angular dependence of spectral intensities can be used to differentiate surface from bulk species. 相似文献
17.
The temperature dependence of the field emission flicker noise spectral density functions has been investigated for potassium adsorbed on tungsten (112) planes by a probe hole technique. By integration of the spectral density functions the noise power for different frequency intervals Δ? is obtained. From the exponential temperature dependence of noise power “activation energies” qΔ? are determined. Plots of these energies versus coverage show a similar “oscillating” behaviour as recently found for or which indicates phase transitions of the adsorbed potassium submonolayers. The noise activation energies are discussed in terms of existing models and a comparison is made between the experimental q values and surface diffusion energies Ed as determined by conventional methods. 相似文献
18.
C. Günther M.V. Banaschik H. Hübel W.D. Schneider K.H. Gonsior P. Herzog 《Nuclear Physics A》1975,244(2):287-300
High spin states in the ) multiplet in 93Mo were investigated with the 93Nb(p, n) 93Mo reaction. A new isomeric state at 2430 keV with a half-life of 3.53±0.18 ns is interpreted as the lower member of the multiplet. A number of further states have been identified. The results are compared to previous experiments and shell model calculations. 相似文献
19.
Spectral luminescence characteristics of the Cs2Na(Er, Yb, Y)Cl6 type upconverter have been measured in the range 300–650 K. A nearly sixfold decrease of the emission intensity of an upconverter was observed in the green area. This emission corresponds to two luminescence transition of Er3+ ions: and . A mechanism of the luminescence intensity decrease has been proposed, in which deexcitation of the level to the level is caused by a neighbouring Er3+ ion being excited to the level. 相似文献
20.
V.V. Nemoshkalenko T.B. Shashkina V.G. Aljeshin A.I. Senkevich 《Journal of Physics and Chemistry of Solids》1975,36(1):37-40
For the borides of the Mn-B system the values of binding energies of Mn 3p, , and B1s core levels were measured on an electron spectrometer. Depending on boride composition the variation of inner level energies is very similar, showing a change of sign in the region of the monoboride phase. The same variation has been observed for some characteristics of X-ray emission spectra from these borides. An attempt is made to understand which of the chemical bonding factors are chiefly responsible for a regular concentration dependence of the X-ray and photoelectron spectra. 相似文献