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1.
The interaction of 2500 eV electrons with carbon monoxide chemisorbed on tungsten {100} was investigated by rapid-scan Auger electron spectroscopy. When no α state was present the O and C signals from the β state of CO were invariant during electron bombardment, giving an upper limit estimate for the electron stimulated desorption cross section, Qβ of 2 × 10?21 cm2. With the crystal at room temperature and saturated with CO, however, electron-beam induced accumulation of carbon was observed and characterised, the rate of the process being independent of CO pressure at pressures above 2 × 10?8 Torr. At 450 K the rate was found to be pressure dependent up to at least 6 × 10?7 Torr. A model is proposed for the accumulation process, which is based on electron beam dissociation of α2-CO to form adsorbed carbon and gaseous O and the creation of new sites for further α2-CO adsorption; it is in quantitative agreement with the results and yields a cross section for ESD of α2-CO (Qα2 = 1.55×10?18cm2) in close agreement with direct measurements. 相似文献
2.
Francisco P.J. Valero 《Journal of Molecular Spectroscopy》1977,68(2):269-279
The absolute intensities of the transitions 401III←000 and 411III←010 of CO2 have been measured from spectra obtained under high resolution. Both the vibration-rotation line intensities and the integrated band intensities are reported. The rotationless transition moment of 401III←000 is deduced and a vibration-rotation interaction factor F(m) = 1+(4.92×10?4)m+(4.4×10?7)m2 is determined. The values obtained are: SBand(401III←000) = (25.54±0.22)×10?5 cm?2atm(293 K)?1, |R000401III| = (1.87±0.02)×10?4D, and SBand(411III←010) = (1.83±0.13)×10?5 cm?2atm(293 K)?1. 相似文献
3.
The magnetic and electric hyperfine splitting frequencies ¦gμ N B HF/h¦ ande 2 qQ/h of the 5/2?1/2[541] ground state of 14h 185Ir in Ni were measured with nuclear magnetic resonance on oriented nuclei to be 360.8(7) MHz and +6.7(2.0) MHz, respectively. The ground state magnetic dipole moment and electric quadrupole moment of185Ir are deduced to be ¦μ¦=2.601 (14)μ N andQ=?1.9(5)b, taking values for the hyperfine field and electric field gradient of BHF=?454.9 (2.3) kG and eq=?0.151(4) × 1017 V/cm2, respectively. The negative quadrupole moment is in agreement with nuclear-orientation data and proves again theI π K=5/2? 1/2 ground state configuration. 相似文献
4.
NMR spectra of samples containing a mixture of hydrogen deuteride HD with pressure of about 80 atm and helium-3 with partial pressure of about 1 atm are analyzed. The ratio of the resonance frequencies of the nuclei, F(3He)/F(H2), is determined to be 0.761786594(2), which is equal to the magnetic moment of the helion (bound in a helium atom) in the units of the magnetic moment of a proton (bound in molecular hydrogen). The uncertainty of two digits in the last place corresponds to a relative error of ??[F(3He)/F(H2)] = 2.6 × 10?9. The use of the known calculated data on the shielding of nuclei in the helium-3 atom (??(3He) = 59924(2) × 10?9) and on the shielding of protons in hydrogen (??(H2) = 26288(2) × 10?9) yields a value of ??(3He)/?? p = ?0.761812217(3) for the free magnetic moment of the helion in the units of the proton magnetic moment. 相似文献
5.
T. N. Mamedov D. G. Andrianov D. Herlach V. N. Gorelkin K. I. Gritsai V. N. Duginov O. Kormann J. Major A. V. Stoikov U. Zimmermann 《JETP Letters》2001,73(12):674-677
Results of studying the temperature dependence of the residual polarization of negative muons in crystalline silicon with germanium (9×10 19 cm ?3 ) and boron (4.1×10 18 , 1.34×10 19 , and 4.9×10 19 cm ?3 ) impurities are presented. It is found that, similarly to n-and p-type silicon samples with impurity concentrations up to ~10 17 cm ?3 , the relaxation rate ν of the magnetic moment of a μ Al acceptor in silicon with a high impurity concentration of germanium (9×10 19 cm ?3 ) depends on temperature as ν~T q , q≈3 at T=(5–30) K. An increase in the absolute value of the relaxation rate and a weakening of its temperature dependence are observed in samples of degenerate silicon in the given temperature range. Based on the experimental data obtained, the conclusion is made that the spin-exchange scattering of free charge carriers makes a significant contribution to the magnetic moment relaxation of a shallow acceptor center in degenerate silicon at T?30 K. Estimates are obtained for the effective cross section of the spin-exchange scattering of holes (σ h ) and electrons (σ e ) from an Al acceptor center in Si: σ h ~10?13 cm2 and σ e ~8×10?15 cm2 at the acceptor (donor) impurity concentration n a (n d )~4×1018 cm?3. 相似文献
6.
M. Marten-Tölle B. Ackermann H. Baltzer T. Bihn V. Grafen C. Günther H. Hausmann N. Singh R. Tölle J. de Boer N. Gollwitzer 《Zeitschrift für Physik A Hadrons and Nuclei》1990,336(1):27-30
Positive and negative parity bands have been followed up to 10+ (possibly 12+) and 11? in224Ra and are compared to the corresponding bands in the isotone226Th. If a constant value of the intrinsic quadrupole moment is assumed for allE2 transitions in224Ra theE1/E2 branching ratios are consistent with an intrinsic dipole moment of ¦Q1¦=0.032(3)e·fm. This small value, as compared to ¦Q1¦=0.30(2)e·fm for226Th, can be explained by an almost complete cancellation of large positive liquid-drop and negative shell-model contributions. 相似文献
7.
《Zeitschrift fur Physik C Particles and Fields》1996,69(4):607-620
We report on a measurement of the proton structure function F 2 in the range 3.5 × 10?5 ≤ x ≤ 4 × 10?3 and 1.5 GeV2 ≤ Q 2 ≤ 15 GeV2 at the ep collider HERA operating at a centre-of-mass energy of ${sqrt s} = 300 {? GeV}$. The rise of F 2 with decreasing x observed in the previous HERA measurements persists in this lower x and Q 2 range. The Q 2 evolution of F 2, even at the lowest Q 2 and x measured, is consistent with perturbative QCD. 相似文献
8.
Several quaternary ammonium bromides possessing long alkyl chains and their mixtures were found to be bromide ion conductors. The ionic conductivities of quaternary ammonium bromides themselves were lower than 10?9 S cm?1 at a room temperature. On the other hand, the eutectic mixtures of the quaternary ammonium bromides showed large increase of ionic conductivity. The best bromide ion conductors were found for the eutectic of Q5, Q7, Q8, and Q12: 4×10?8 S cm?1 at 30°C, and 6.3×10?6 S cm?1 at 50°C. Addition of asymmetric quarternary ammonium bromides had a negative effect on the ionic conductivity. These results were explained by a space filling factor in the solid. 相似文献
9.
The moment of inertia of the proto neutron star PSR J0348+0432 is studied in the framework of relativistic mean field theory under neutrino trapped. We find that the temperature of the PNS PSR J0348+0432 increases with the increase of the baryon number density and at the center of the star it is in the range Tc = 41.662–45.685 MeV. Corresponding to the observation mass 1.97–2.05 M⊙, the radius of the NS PSR J0348+0432 is in the range 12.948–12.16 km whereas that of the PNS PSR J0348+0432 is in the range 14.46–13.561 km. The radius of the PNS PSR J0348+0432 has increased by 11.7%–11.5% compared with that of the NS PSR J0348+0432. The central moment of inertia of the PNS PSR J0348+0432 is in the range 2.207?×?1045–1.914?×?1045 g cm2 whereas that of the NS PSR J0348+0432 is only in the range 1.9?×?1045–1.552?×?1045 g cm2. Compared with the moment of inertia of the NS PSR J0348+0432, the central moment of inertia of the PNS PSR J0348+0432 increases by 16%–23%. 相似文献
10.
Electric dipole moment and chromoelectric dipole moment of the top quark inSU(3)C×SU(3)L×U(1)X model
We show that inSU(3) C ×SU(3) L ×U(1) X model, the leading contribution to the electric and chromolelectric dipole moment of the top quark is due to the one-loop diagrams which come from exchanging the charged and neutral Higgs bosons. The dipole moments are typically of the order of 10?19 e-cm and 10?19 g-cm respectively, for the values of relative phases of the vev's such that CP violation is maximal. From an experimental point of view, theq 2 dependence of dipole moment form factors is given. 相似文献
11.
We have performed a Monte Carlo study of photon-gluon interactions at theep collider HERA. We show that it is possible to determine the fractional momentum carried by the gluon (x g) from hadronic informations alone. In particular, in the photoproduction region, where thex andQ 2 are badly measured, this could be the only global physical variable of interest, together with the hadronic invariant mass. The study of these quantities would allow a direct measurement of the gluon density of the proton in the rangex g=2.5×10?3∶5×10?1. 相似文献
12.
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
13.
The collision-induced fundamental infrared absorption band of hydrogen in binary mixtures H2He and H2Ne at 77, 195, 273, and 298 K has been studied with absorption path lengths of 27 and 105 cm for gas densities up to 530 amagat for several base densities of hydrogen. In each of these mixtures the enhancement absorption profiles show, in addition to the usual splitting of the Q branch into the main QP and QR components, a splitting of the S(1) line into the SP(1) and SR(1) components at all the experimental temperatures and a secondary splitting of the main QP component into the QP(3) and QR(3) components at 273 and 298 K. The profiles of H2He at 77 K also show a splitting of the S(0) line into SP(0) and SR(0). Integrated absorption coefficients were measured and binary and ternary absorption coefficients were derived. Van Kranendonk's theory of the ‘exponential-4’ model for the induced dipole moment was applied to the experimental binary absorption coefficients. The quadrupolar parts of these coefficients were calculated from the known molecular parameters and were then subtracted from the experimental values to obtain the overlap parts. The overlap parameters λ and ρ, giving respectively the magnitude and range of the overlap moment, were determined for each of the mixtures by obtaining the best fit of the calculated overlap part of the binary absorption coefficient as a function of temperature to the experimental values of the overlap parts. The values of λ, ρ, and μ(σ) (the overlap induced dipole moment at the Lennard-Jones intermolecular diameter σ) are as follows:
Mixture | λ | ρ | μ(σ) |
H2He | 5.6 × 10?3 | 0.24 Å | 2.92 × 10?2ea0 |
H2Ne | 9.0 × 10?3 | 0.29 Å | 4.85 × 10?2ea0 |