共查询到20条相似文献,搜索用时 328 毫秒
1.
J. Stanzel F. Burmeister M. Neeb 《Applied Physics A: Materials Science & Processing》2010,100(1):21-29
We have studied the dynamics of photoexcited tungsten cluster anions Wn-\mathrm{W}_{n}^{-} (n=3,4,…,14) by means of time-resolved two-photon photodetachment spectroscopy. At an excitation energy of h
ν
pump=1.56 eV the photoinduced dynamics is mainly dominated by fast electronic relaxation processes. For the smallest clusters,
i.e., W3-\mathrm{W}_{3}^{-}, W4-\mathrm{W}_{4}^{-}, and W5-\mathrm{W}_{5}^{-}, individual relaxation channels have been identified and resolved on a timescale well below 100 fs. The time constants for
the decay of nascent and secondary electrons have been deduced from a Bloch model. Complete thermalization takes place for
all clusters on a timescale of ∼1 ps. 相似文献
2.
设计了一套紧凑的光电子成像装置,它包括解离式光电子贴附负离子源、垂直安装的高分辨阈值光电子速度成像装置和线性飞行时间质谱仪.紫外光辐射金属表面诱导低能光电子发射,再通过低能电子贴附超声分子束产生高强度和冷的负离子源.结合这种负离子源和飞行时间质谱-光电子成像仪装置,仪器的质量分辨能达到200左右,能量分辨优于3%(即对1 eV动能的电子,分辨达到30 meV).此外,使用该实验装置获得了CH3S-和S2-在611.46 nm下的低能阈值光电子成像结果.同时得到了CH3S和S2的更精确的电子亲和势分别为1.8626±0.0020和1.6744±0.0035 eV.初步的结果证明了该装置对研究阈值光电子成像精确测量光电子亲和势非常有效 相似文献
3.
Combined constraints on modified Chaplygin gas model from cosmological observed data: Markov Chain Monte Carlo approach 总被引:1,自引:0,他引:1
We use the Markov Chain Monte Carlo method to investigate a global constraints on the modified Chaplygin gas (MCG) model as
the unification of dark matter and dark energy from the latest observational data: the Union2 dataset of type supernovae Ia
(SNIa), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and
the cosmic microwave background (CMB) data. In a flat universe, the constraint results for MCG model are, Wbh2 = 0.02263+0.00184-0.00162 (1s)+0.00213-0.00195 (2s){\Omega_{b}h^{2}\,{=}\,0.02263^{+0.00184}_{-0.00162} (1\sigma)^{+0.00213}_{-0.00195} (2\sigma)}, Bs = 0.7788+0.0736-0.0723(1s)+0.0918-0.0904 (2s){B_{s}\,{=}\,0.7788^{+0.0736}_{-0.0723}(1\sigma)^{+0.0918}_{-0.0904} (2\sigma)}, a = 0.1079+0.3397-0.2539 (1s)+0.4678-0.2911 (2s){\alpha\,{=}\,0.1079^{+0.3397}_{-0.2539} (1\sigma)^{+0.4678}_{-0.2911} (2\sigma)}, B = 0.00189+0.00583-0.00756(1s)+0.00660-0.00915 (2s){B\,{=}\,0.00189^{+0.00583}_{-0.00756}(1\sigma)^{+0.00660}_{-0.00915} (2\sigma)}, and H0=70.711+4.188-3.142 (1s)+5.281-4.149(2s){H_{0}=70.711^{+4.188}_{-3.142} (1\sigma)^{+5.281}_{-4.149}(2\sigma)}. 相似文献
4.
N. Kaiser 《The European Physical Journal A - Hadrons and Nuclei》2010,46(3):373-378
We calculate the one-photon loop radiative corrections to the neutral pion-pair photoproduction process p-g ?p-p0p0\pi^-\gamma \ensuremath \rightarrow\pi^-\pi^0\pi^0 . At leading order this reaction is governed by the chiral pion-pion interaction. Since the chiral p+ \pi^{+}_{}
p- \pi^{-}_{}
? \rightarrow
p0 \pi^{0}_{}
p0 \pi^{0}_{} contact vertex depends only on the final-state invariant mass it factors out of all photon loop diagrams. We give analytical
expressions for the multiplicative correction factor R ~ a/2p\ensuremath R\sim \alpha/2\pi arising from eight classes of contributing one-photon loop diagrams. An electromagnetic counterterm has to be included in
order to cancel the ultraviolet divergences generated by the photon loops. Infrared finiteness of the virtual radiative corrections
is achieved (in the standard way) by including soft photon radiation below an energy cut-off l \lambda . The radiative corrections to the total cross-section vary between +2% and -2% for center-of-mass energies from threshold
up to 7mp\ensuremath 7m_{\pi} . We study also the radiative corrections to the p0p0\ensuremath \pi^0\pi^0 mass spectrum. 相似文献
5.
Y. A. Gauduel Y. Glinec J.-P. Rousseau F. Burgy V. Malka 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(1):121-135
The damages triggered by ionizing radiation on chemical and biological targets depend on the survival probability of radicals
produced in clusters of ionization-excitation events. In this paper, we report on femtolysis (FEMTOsecond radioLYSIS) of pure
liquid water using an innovative laser produced high-energy, ultra-short electron bunches in the 2.5-15 MeV range and high
energy radiation femtochemistry (HERF) measurements. The short-time monitoring of a primary reducing radical, hydrated electron
e-aq^{-}_{aq}, has been performed in confined ionization spaces (nascent spurs). The calculated yield of hydrated electrons at early time,
G(e-aq)ETG({\rm e}^{-}_{aq})_{ET}, is estimated to be 6.5 ± 0.5 (number/100 eV) at t ~ 5 ps after the ultrafast energy deposition. This estimated value is high compare to (i) the available data of previous
works that used scavenging techniques; (ii) the predictions of stochastic water radiolysis modelling for which the initial
behaviour of hydrated electron is investigated in the framework of a classical diffusion regime of independent pairs. The
HERF developments give new insights into the early ubiquitous radical escape probability in nascent aqueous spurs and emphasize
the importance of short-lived solvent bridged electron-radical complexes
[H3O+...{\rm H}_{3}{\rm O}^{+...}
eaq-{\rm e}_{aq}^{-} ..OH]nH2O{\rm OH}]_{n{\rm H}_2{\rm O}}
(non-independent pairs). A complete understanding of the
G(e-aq)ET{\rm e}^{-}_{aq})_{ET} value needs to account for quantum aspects of 1s-like trapped electron ground state and neoformed
prototropic radicals that govern ultra-fast recombination processes within these non-independent pair configurations. Femtolysis
data
emphasize that within a time-dependent non-diffusion regime, spatio-temporal correlations between hydrated electron and nearest
neighbours OH radical or hydrated proton (H3O+{\rm H}_{3}{\rm O}^{+}) would assist ultrafast anisotropic 1D recombination within solvent bridged electron-radical complexes. The emerging HERF
domain would provide guidance for understanding of ultrashort-lived sub-structure of tracks and stimulate future semi-quantum
simulations on prethermal radical reactions. 相似文献
6.
S. K. El-Labany W. M. Moslem Kh. A. Shnishin S. A. El-Tantawy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(2):409-420
By using the hydrodynamic equations of positive and two negative ions,
Boltzmann electron density distribution, and Poisson equation with immobile
positive/negative dust particles, a cylindrical Korteweg-de Vries (CKdV)
equation is derived for small but finite amplitude ion-acoustic waves. At the
critical total negative ion concentration and/or the critical density rate of
the second-negative ions, the pulses collapse at this limit as nonlinearity
fails to balance dispersion. Then the CKdV equation is not appropriate to
describe the system. Therefore, the modified CKdV (MCKdV) and extended CKdV
(ECKdV) equations are derived at the critical plasma compositions and in the
vicinity of the critical plasma compositions, respectively. The physical
parameters of two plasma environments (e.g., Xe+–F-–SF6-_{6}^{-} and
Ar+–F-–SF6-_{6}^{-} plasmas) are examined on the wave phase velocity and
the nonlinear localized pulse profile. The latter should satisfy necessary
condition to exist. The localized pulse of Ar+–F-–SF6-_{6}^{-} plasma is
much spiky than Xe+–F-–SF6-_{6}^{-} plasma. Thus, the mass ratio of the
negative-to-positive ions is focused upon and it emphasizes to play an
important role on the pulse profile. Dependence of the geometrical divergence
on the pulse profile is also investigated, which indicates that the localized
pulse damps with time. The implications of our results agrees with the
experimental observations. 相似文献
7.
V. V. Sarantsev K. N. Ermakov L. M. Kochenda V. I. Medvedev V. A. Nikonov O. V. Rogachevsky A. V. Sarantsev S. G. Sherman V. A. Trofimov A. A. Vasiliev 《The European Physical Journal A - Hadrons and Nuclei》2010,43(1):11-16
A detailed investigation of the reaction np
? \rightarrow
pp
p- \pi^{{-}}_{} has been carried out using the data obtained with the continuous neutron beam produced by charge exchange scattering of protons
off the deuterium target. Partial-wave event-by-event analysis based on the maximum likelihood method was applied to determine
contributions of different partial waves to the pion production process. A combined analysis of the np
? \rightarrow
pp
p- \pi^{{-}}_{} and pp
? \rightarrow
pp
p0 \pi^{{0}}_{} data measured in the same energy region allows us to determine the contribution of isoscalar partial waves (I = 0 in the momentum range from 1.1 up to 1.8GeV/c . The decay of isoscalar partial waves into the (1
S
0)pp
p \pi channel provides us with a good tool for the determination of the pp
S -wave scalar scattering length in the final state which was found to be a
pp = - 7.5±0.3 fm. 相似文献
8.
9.
L. Museur A.V. Kanaev M.C. Castex L. Moussavizadeh R. von Pietrowski T. Möller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):73-78
Charge-transfer reactions are observed in a photoluminescence study of NF3\rm NF_3-doped free krypton clusters. They show up in emissions from Kr+F-\rm Kr^{+}F^{-}free excimers ejected from the clusters, and from excited Kr2+F-\rm Kr_2^{+}F^{-}and Kr2+(NF3)m-{\rm Kr}_2^{+}({\rm NF}_3)_m^{-} (m 3(m\geq 1) solvated in the clusters. The results show that reaction dynamics in clusters differs considerably from that in the gas and solid phases. 相似文献
10.
J. Moc 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(2):397-402
We have studied the interaction of Al13-_{13}^{-} anion
cluster with H2. Both the long range interaction and dissociative
adsorption have been examined using the established correlated ab initio
methods, MP2 and CCSD(T), in conjunction with the augmented correlation
consistent basis sets up to aug-cc-pVTZ. The formation of the weakly bound
(physisorbed) end-on anion complex Al13-_{13}^{-}...H2 is
predicted for the interacting Al...H distances of 3.95 ? with the
H-H axis pointing towards the ‘hollow’ site of Al13-_{13}^{-} and binding
energy (De)D_{e}) of 0.7 kcal/mol at the estimated complete basis set (CBS)
limit of CCSD(T). The barrier height for H2 dissociation on
Al13-_{13}^{-} of 41.6 (42.9) kcal/mol calculated at the ZPVE-corrected
CCSD(T)/aug-cc-pVTZ (estimated CCSD(T)/CBS) level is at least twice as large
as that evaluated by us for a dissociative adsorption of H2 on an
open-shell Al13 neutral cluster. To our knowledge, this report presents
the first “benchmark” quality study of the physisorption and dissociative
chemisorption of molecular hydrogen on Al13-_{13}^{-} anion cluster. 相似文献
11.
This paper considers Hardy–Lieb–Thirring inequalities for higher order differential operators. A result for general fourth-order
operators on the half-line is developed, and the trace inequality
tr( (-D)2 - CHRd,2\frac1|x|4 - V(x) )-g £ Cgò\mathbbRd V(x)+g+ \fracd4 dx, g 3 1 - \frac d 4,\mathrm{tr}\left( (-\Delta)^2 - C^{\mathrm{HR}}_{d,2}\frac{1}{|x|^4} - V(x) \right)_-^{\gamma}\leq C_\gamma\int\limits_{\mathbb{R}^d} V(x)_+^{\gamma + \frac{d}{4}}\,\mathrm{d}x, \quad \gamma \geq 1 - \frac d 4, 相似文献
12.
By introducing the mixing of scalar mesons in the chiral SU(3) quark model, we dynamically investigate the baryon-baryon interaction. The hyperon-nucleon and nucleon-nucleon interactions
are studied by solving the resonating group method (RGM) equation in a coupled-channel calculation. In our present work, the
experimental lightest pseudoscalar p \pi, K,h \eta,h¢ \eta^{{\prime}}_{} mesons correspond exactly to the chiral nonet pseudoscalar fields p \pi, K,h \eta,h¢ \eta^{{\prime}}_{} in the chiral SU(3) quark model. The h \eta,h¢ \eta^{{\prime}}_{} mesons are considered as the mixing of singlet and octet mesons, and the mixing angle qps \theta_{{ps}}^{} is taken to be -23° . For scalar nonet mesons, we suppose that there exists a correspondence between the experimental lightest scalar f
0(600) , k \kappa , a
0(980) , f
0(980) mesons and the theoretical scalar nonet s \sigma , k \kappa , s¢ \sigma^{{\prime}}_{} , e \epsilon fields in the chiral SU(3) quark model. For scalar mesons, we consider two different mixing cases: one is the ideal mixing and another is the qs \theta_{s}^{} = 19° mixing. The masses of the s¢ \sigma^{{\prime}}_{} and e \epsilon mesons are taken to be 980MeV, which are just the masses of the experimental a
0(980) , f
0(980) mesons. The mass of the s \sigma meson is an adjustable parameter and is decided by fitting the binding energy of the deuteron, the masses of 560MeV and 644MeV
are obtained for the ideal mixing and the qs \theta_{s}^{} = 19° mixing, respectively. We find that, in order to reasonably describe the YN interactions, the mass of the k \kappa meson is near 780MeV for the ideal mixing. However, we must enhance the mass of the k \kappa meson for the qs \theta_{s}^{} = 19° mixing, the 1050MeV is favorably used in the present work. The experimental s \sigma and k \kappa scalar mesons are very strange, both have larger widths. Hence, no matter what kind of mixing is considered, all the masses
of scalar mesons we used in the present work seem to be consistent with the present PDG information. 相似文献
13.
We make the cosmological constant, Λ, into a field and restrict the variations of the action with respect to it by causality.
This creates an additional Einstein constraint equation. It restricts the solutions of the standard Einstein equations and
is the requirement that the cosmological wave function possess a classical limit. When applied to the Friedmann metric it
requires that the cosmological constant measured today, t
U
, be L ~ tU-2 ~ 10-122{\Lambda \sim t_{U}^{-2} \sim 10^{-122}} , as observed. This is the classical value of Λ that dominates the wave function of the universe. Our new field equation
determines Λ in terms of other astronomically measurable quantities. Specifically, it predicts that the spatial curvature
parameter of the universe is Wk0 o -k/a02H2=-0.0055{\Omega _{\mathrm{k0}} \equiv -k/a_{0}^{2}H^{2}=-0.0055} , which will be tested by Planck Satellite data. Our theory also creates a new picture of self-consistent quantum cosmological
history. 相似文献
14.
In this paper, we consider the global wellposedness of the 3-D incompressible anisotropic Navier-Stokes equations with initial
data in the critical Besov-Sobolev type spaces B{\mathcal{B}} and
B-\frac12,\frac124{\mathcal{B}^{-\frac12,\frac12}_4} (see Definitions 1.1 and 1.2 below). In particular, we proved that there exists a positive constant C such that (ANS
ν
) has a unique global solution with initial data u0 = (u0h, u03){u_0 = (u_0^h, u_0^3)} which satisfies
||u0h||B exp(\fracCn4 ||u03||B4) £ c0n{\|u_0^h\|_{\mathcal{B}} \exp\bigl(\frac{C}{\nu^4} \|u_0^3\|_{\mathcal{B}}^4\bigr) \leq c_0\nu} or
||u0h||B-\frac12,\frac124 exp(\fracCn4 ||u03||B-\frac12,\frac1244) £ c0n{\|u_0^h\|_{\mathcal{B}^{-\frac12,\frac12}_{4}} \exp \bigl(\frac{C}{\nu^4} \|u_0^3\|_{\mathcal{B}^{-\frac12,\frac12}_{4}}^4\bigr)\leq c_0\nu} for some c
0 sufficiently small. To overcome the difficulty that Gronwall’s inequality can not be applied in the framework of Chemin-Lerner
type spaces, [(Lpt)\tilde](B){\widetilde{L^p_t}(\mathcal{B})}, we introduced here sort of weighted Chemin-Lerner type spaces, [(L2t, f)\tilde](B){\widetilde{L^2_{t, f}}(\mathcal{B})} for some apropriate L
1 function f(t). 相似文献
15.
Measurement of the diffractive cross section in deep inelastic scattering using ZEUS 1994 data 总被引:1,自引:0,他引:1
The DIS diffractive cross section, dsdiffg* p ? XN/dMXd\sigma^{di\!f\!f}_{\gamma^* p \to XN}/dM_X, has been measured in the mass range MX < 15M_X < 15 GeV for g*p\gamma^*p c.m. energies 60 < W < 20060 < W < 200 GeV and photon virtualities Q2 = 7Q^2 = 7 to 140 GeV2^2. For fixed Q2Q^2 and MXM_X, the diffractive cross section rises rapidly with WW, dsdiffg*p ? XN(MX,W,Q2)/dMX μ Wadiffd\sigma^{di\!f\!f}_{\gamma^*p \to XN}(M_X,W,Q^2)/dM_X \propto W^{a^{diff}} with adiff = 0.507 ±0.034 (stat)+0.155-0.046(syst)a^{diff} = 0.507 \pm 0.034 (stat)^{+0.155}_{-0.046}(syst) corresponding to a t-averaged pomeron trajectory of [`( a\mathbb P )] = 1.127 ±0.009 (stat)+0.039-0.012 (syst)\overline{ \alpha_{_{{\mathbb P}}} } = 1.127 \pm 0.009 (stat)^{+0.039}_{-0.012} (syst) which is larger than [`( a\mathbb P )]\overline{ \alpha_{_{{\mathbb P}}} } observed in hadron-hadron scattering. The W dependence of the diffractive cross section is found to be the same as that of the total cross section for scattering of virtual photons on protons. The data are consistent with the assumption that the diffractive structure function FD(3)2F^{D(3)}_2 factorizes according to x\mathbb P FD(3)2 (x\mathbb P,b,Q2) = (x0/ x\mathbb P)n FD(2)2(b,Q2)x_{_{{\mathbb P}}} F^{D(3)}_2 (x_{_{{\mathbb P}}},\beta,Q^2) = (x_0/ x_{_{{\mathbb P}}})^n F^{D(2)}_2(\beta,Q^2). They are also consistent with QCD based models which incorporate factorization breaking. The rise of x\mathbb P FD(3)2x_{_{{\mathbb P}}} F^{D(3)}_2 with decreasing x\mathbb Px_{_{{\mathbb P}}} and the weak dependence of FD(2)2F^{D(2)}_2 on Q2Q^2 suggest a substantial contribution from partonic interactions. 相似文献
16.
Using chiral perturbation theory we calculate for pion Compton scattering the isospin-breaking effects induced by the difference
between the charged and neutral pion mass. At one-loop order this correction is directly proportional to mp±2-mp02\ensuremath{m_{\pi^\pm}^2-m_{\pi^0}^2} and free of (electromagnetic) counterterm contributions. The differential cross-section for charged pion Compton scattering
p-g? p-g\ensuremath{\pi^-\gamma \rightarrow \pi^-\gamma} gets affected (in backward directions) at the level of a few permille. At the same time the isospin-breaking correction leads
to a small shift of the pion polarizabilities by d(ap- bp) @ 1.3 ·10-5\ensuremath{\delta(\alpha_\pi- \beta_\pi) \simeq 1.3 \cdot 10^{-5}} fm^3. In case of the low-energy gg? p0p0\ensuremath{\gamma\gamma \rightarrow \pi^0\pi^0} reaction isospin breaking manifests itself through a cusp effect at the p+p-\ensuremath{\pi^+\pi^-} threshold. We give an improved estimate for it based on the empirical p \pi
p \pi -scattering length difference a0-a2\ensuremath{a_0-a_2} . 相似文献
17.
Xing-Lei Xu Shi-Min Xu Yun-Hai Zhang Hong-Qi Li Ji-Suo Wang 《International Journal of Theoretical Physics》2011,50(10):3176-3185
The new intermediate entangled state |η;θ〉 is proposed by virtue of IWOP technique, which is the common eigenvector of [([^(x)]1 - [^(x)]2)cosq-([^(p)]1 - [^(p)]2)sinq][(\hat{x}_{1} - \hat{x}_{2})\cos\theta -(\hat{p}_{1} - \hat{p}_{2})\sin\theta ] and [([^(x)]1 +[^(x)]2)sinq+ ([^(p)]1 + [^(p)]2)cosq][(\hat{x}_{1} +\hat{x}_{2})\sin\theta + (\hat{p}_{1} + \hat{p}_{2})\cos\theta ]. The squeezing transformation operator, Hadamard transformation operator, Fresnel transformation operator and Radon transform
operator are constructed by |η;θ〉. 相似文献
18.
K. Sekimoto M. Takayama 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(3):589-599
The change in the distribution pattern of negative ions HO–, NOx-_{x}^{-} and COx-_{x}^{-} observed on arbitrary point-to-plane electrode configuration has been investigated by varying the angle of needle to the
plane electrode, under atmospheric pressure corona discharge
conditions. The stationary inhomogeneous electric field distributions between the point-to-plane electrodes with arbitrary
needle angle were calculated. The experimental and theoretical results obtained suggested that the negative ion evolutions
progress along field lines established between
the electrodes with arbitrary configurations and the resulting terminal ion formation on a given field line is attributable
to the electric field strength on the needle tip surface where the field line arose. The NOx-_{x}^{-} and COx-_{x}^{-} ions were dominantly produced on the field lines arising from the needle tip apex region with the highest electric field
strength, while the field lines emanating from the tip peripheral regions with lower field strength resulted in the formation
of the HO– ion. 相似文献
19.
Zhi-Gang Wang 《The European Physical Journal C - Particles and Fields》2009,63(1):115-122
In this article, we assume that there exists a scalar
Ds*[`(D)]s*D_{s}^{\ast}{\bar{D}}_{s}^{\ast}
molecular state in the J/ψ
φ invariant mass distribution, and we study its mass using the QCD sum rules. The predictions depend heavily on the two criteria
(pole dominance and convergence of the operator product expansion) of the QCD sum rules. The value of the mass is about
MDs*[`(D)]s*=(4.43±0.16)M_{D_{s}^{\ast}{\bar{D}}_{s}^{\ast}}=(4.43\pm0.16)
GeV, which is inconsistent with the experimental data. The
Ds*[`(D)]s*D_{s}^{\ast}{\bar{D}}_{s}^{\ast}
is probably a virtual state and is not related to the meson Y(4140). Another possibility, such as a hybrid charmonium, is not excluded. 相似文献
20.
The conductivity of glasses in the
50\textP\text2 \textO\text5 - x\textV\text2 \textO\text5 - ( 50 - x )\textLi\text2 \textO50{\text{P}}_{\text{2}} {\text{O}}_{\text{5}} - x{\text{V}}_{\text{2}} {\text{O}}_{\text{5}} - \left( {50 - x} \right){\text{Li}}_{\text{2}} {\text{O}} system was studied as a function of temperature and composition. For all compositions, the conductivity variation as a function
of temperature followed an Arrhenius type relationship. Isothermal variation of conductivity as a function of composition
showed a minimum for a molar ratio x near 20. Probable mechanisms for decrease of conductivity with decrease of vanadium oxide concentration were explained. The
minimum in room temperature was attributed to increase of V4+/V5+ with decrease of vanadium oxide in specific concentrations of vanadium oxide. Activation energy increased with decrease of
V2O5 content. This behavior was attributed to increase of average spacing between vanadium ions. 相似文献
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