共查询到20条相似文献,搜索用时 46 毫秒
1.
Chuandong Jia Biao Wu Jianjun Liang Xiaojuan Huang Xiao-Juan Yang 《Journal of fluorescence》2010,20(1):291-297
N-Phenyl-N’-(3-quinolinyl)urea (1) has been developed as a highly selective colorimetric and ratiometric fluorescent chemosensor for fluoride ion based on a
proton transfer mechanism. Evidences for the mechanism were provided by UV-vis and fluorescence titration and especially 1H and 19F NMR experiments. The sensor gave the largest ratiometric fluorescent response reported so far (Rmax/Rmin = 2620) to fluoride. Taking H+ as the “recovering reagent”, the sensor can be reversibly “used” and “recovered” for several cycles with only a slight decay
of the response ability. 相似文献
2.
《The European Physical Journal C - Particles and Fields》2007,49(2):545-558
Ratios of the ψ′ over the J/ψ production cross sections in the dilepton channel for C, Ti and W targets have been measured in 920 GeV proton-nucleus
interactions with the HERA-B detector at the HERA storage ring. The ψ′ and J/ψ states were reconstructed in both the μ+μ- and the e+e- decay modes. The measurements covered the kinematic range -0.35≤xF≤0.1 with transverse momentum pT≤4.5 GeV/c. The angular dependence of the ratio has been used to measure the difference of the ψ′ and J/ψ polarization. All results for the muon and electron decay channels are in good agreement: their ratio, averaged over
all events, is Rψ′(μ)/Rψ′(e)=1.00±0.08±0.04. This result constitutes a new, direct experimental constraint on the double ratio of branching fractions,
(B′(μ)B(e))/(B(μ)B′(e)), of ψ′ and J/ψ in the two channels. The ψ′ to J/ψ production ratio is almost constant in the covered xF range and shows a slow increase with pT. 相似文献
3.
The results of our NMR, EPR and magnetic susceptibility measurements in the paramagnetic state of TlMnCl3 are reported here. The NMR paramagnetic shift of thallium is found to be small but positive. Mn2+ EPR line is exchange narrowed. The susceptibility measurements indicate an antiferromagnetic transition. The heat of crystallographic
phase transition ΔH, in TlMnCl3 has been measured using differential scanning calorimetry. The crystallographic phase transition appears to be first order
and ΔH is unusually low viz. 10 cal mole−1. In the case of KMnF3 ΔH, which is reported here for the first time, is determined to be 2 cal mole−1. 相似文献
4.
Yu-Ming Wang Hao Zou Zheng-Tao Wei Xue-Qian Li Cai-Dian Lü 《The European Physical Journal C - Particles and Fields》2008,54(1):107-121
Within the standard model, we investigate the semi-leptonic weak decays of J/ψ. The various form factors of J/ψ making the
transition to a single charmed meson (D(*)
(d,s)) are studied in the framework of QCD sum rules. These form factors fully determine the rates of the weak semi-leptonic decays
of J/ψ and provide valuable information on non-perturbative QCD effects. Our results indicate that the decay rate of the semi-leptonic
weak decay mode J/ψ→D(*)-
s+e++νe is at the order of 10-10.
PACS 13.20.Gd; 13.25.Gv; 11.55.Hx 相似文献
5.
Sol Schwartzman 《Communications in Mathematical Physics》2011,306(1):187-191
In n-dimensional Euclidean space let us be given an infinitely differentiable real valued function V that is bounded below. We associate with the formal operator that sends a complex valued function ψ into −div(grad ψ) + V
ψ a uniquely defined self adjoint operator which we will denote by −Δ + V. 相似文献
6.
Approximating the shape of the magneto-thermoelectric power (TEP) ΔS(T,H) measured in Bi2Sr2CaCu2Oy by an asymmetric linear triangle of the form ΔS(T,H)≃S
p
(H)±B
±(H)(T
c
−T) with positive B
−(H) and B
+(H) defined below and above T
c
, we observe that B
+(H) ≃2B
−(H). To account for this asymmetry, we explicitly introduce the field-dependent chemical potential μ(H) of holes into the Ginzburg-Landau theory and calculate both an average ΔS
av(T,H) and fluctuation contribution ΔS
fl(T,H) to the total magneto-TEP ΔS(T,H). As a result, we find a rather simple relationship between the field-induced variation of the chemical potential in this
material and the above-mentioned magneto-TEP data around T
c
, viz. Δ μ(H)∝S
p
(H).
Zh. éksp. Teor. Fiz. 116, 257–262 (July 1999)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
7.
Xiang Liu 《The European Physical Journal C - Particles and Fields》2008,54(3):471-474
Very recently a new enhancement around 4.05 GeV was observed by the Belle experiment. We discuss some possible assignments
for this enhancement, i.e. the ψ(3S) and D*D̄* molecular states. In these two assignments, Y(4008) can decay into J/ψπ0π0 with a branching ratio comparable with that of Y(4008)→J/ψπ+π-. Thus, one suggests high energy experimentalists to look for Y(4008) in J/ψπ0π0 channel. Furthermore one proposes further experiments to search for the missing channels DD̄, DD̄*+h.c. and especially χcJπ+π-π0 and ηcπ+π-π0, which will be helpful to distinguish the ψ(3S) and D*D̄* molecular state assignments for this new enhancement.
PACS 13.30.Eg 13.75.Lb 相似文献
8.
A.W.K. Mok K.J. Sebastian 《The European Physical Journal C - Particles and Fields》2008,56(2):189-202
Using the helicity formulism, we calculate the combined angular distribution function of the polarized gamma photons and electron
in the cascade process pp̄→ψ’→χJ+γ1→ψ+γ2+γ1→e++e-+γ2+γ1 (J=0,1,2), when p̄ and p are unpolarized. We also present the partially integrated angular distribution functions in different
cases. Our results show that by measuring the two-particle angular distribution of γ1 and γ2 and that of γ2 and e- with the polarization of either one of the two particles, one can determine the relative magnitudes as well as the relative
phases of the helicity amplitudes in the radiative decay processes ψ’→χJ+γ1 and χJ→ψ+γ2.
PACS 11.80.Cr; 13.20.Fc; 13.60.Le; 14.40.Gx 相似文献
9.
Dr. Minakshi L. K. Jha S. N. Chatterjee B. N. Roy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):331-339
H+ and He2+ impact single and double ionization cross
sections of ground state lead atoms have been calculated in the binary
encounter approximation. Calculations of direct double ionization cross
sections have been performed in the modified double binary encounter model.
The accurate expressions of σΔE (cross-section for energy
transfer ΔE) and Hartree-Fock velocity distributions for the target
electrons have been used throughout the calculations. Contributions to
double ionization from Auger effect following ionization of inner shells
have been considered in the present work. Our H+ impact single and
double ionization cross sections are in good agreement with the experimental
observations. In calculations of He2+ impact cross sections, the
present theoretical approach shows limited success in the experimentally
investigated region (50–350 keV amu-1). 相似文献
10.
Xiao-Gang He Xue-Qian Li Xiang Liu Jian-Ping Ma 《The European Physical Journal C - Particles and Fields》2007,49(3):731-736
Recently the BES collaboration has announced the observation of a resonant state in the π+π-η’ spectrum in J/ψ→γπ+π-η’ decay. Fitting the data with a 0-+ state, the mass is determined to be 1833.7 MeV with 7.7σ statistic significance. This state is consistent with the one extracted
from previously reported pp̄ threshold enhancement data in J/ψ→γpp̄. We study the properties of this state using QCD anomaly
and QCD sum rules, assuming X(1835) to be a pseudoscalar, and we show that it is consistent with the data. We find that this
state has a sizeable matrix element , leading to branching ratios of (2.61–7.37)×10-3 and (2.21–10.61)×10-2 for J/ψ→γGp and for Gp→π+π-η′, respectively. Combining the calculated branching ratio of J/ψ→γGp and data on threshold enhancement in J/ψ→γpp̄, we determine the coupling for the Gp–p–p̄ interaction. We finally study the branching ratios of the other J/ψ→γ+three mesons decay modes. We find that J/ψ→γGp→γ(π+π-η,KKπ0) can provide useful tests for the mechanism proposed.
PACS 11.55.Hx; 12.39.Fe; 12.39.Mk; 13.25.Gv 相似文献
11.
In this paper certain correspondences have been shown among various formulations of coupled-cluster theories for many electron
closed-shell systems. Specifically it is shown that (i) the energy functional using unitary ansatz of the form exp (T−T
+) is exactly sameorder by order inT with the size-consistent energy functional 〈ψ|H|ψ〉/〈ψ|ψ〉 recently obtained by us in coupled-cluster framework; (ii) in the framework of unitary ansatz of the form exp (T−T
+), both non-variational and variational approaches lead to identical equations upto any given order inT andT
+ inT∼T
2 approximation; (iii) variational procedure using our size-consistent energy functional or using the functional obtained in
the framework of unitary ansatz (as envisaged by Kutzelnigg) leads to energy in both cases, inT∼T
2 approximation, for a total of quadratic powers inT andT
+, same as Cizek’s linearised coupled pair many electron theory energy; (iv) in case of practical calculation of the energy
through the variational procedures using our size-consistent energy functional and the functional in unitary ansatz framework,
there is a loss of upper bound. 相似文献
12.
W. Higemoto K. Satoh N. Nishida K. Nishiyama K. Nagamine 《Hyperfine Interactions》1997,106(1-4):39-44
Using a pulsed muon beam, we have investigated the microscopic μ+ behavior in solid H2 and D2 down to 0.6 K by the μ+SR method. From the studies of μ+ spin relaxation phenomena in solid para‐ H2 and ortho‐ D2, we have found that μ+ forms three distinct microscopic states; H2μ+( D2μ+)(20\sim25\%), muonium (15\sim20\%) and μ+(\sim60\%). In H2μ+, the μ+ spin is depolarized in solid para‐ H2 and a local magnetic field Bloc=1\sim2 G is deduced from LF‐μ+SR measurements. The magnitude of Bloc is inconsistent with the magnetic dipolar field (\sim25 G) expected from the magnetic moments of two protons in the H2μ+ molecule and suggests that the H2μ+ molecule might be in the rotationally excited state. From LF‐μ+SR measurements, muonium and μ+ have been found to diffuse in solid o‐ D_2. The diffusion rate of muonium is two order of magnitude larger than that of μ+.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
It is pointed out that the coupling characterizing theψ-γ vertex must change substantially between the limits,ψ on mass-shell which occurs inψ→e
+
e
− and photon on mass-shell which is relevant in radiative decays likeψ→ππγ, ψ→ηγ and photoproduction ofψ. This has the consequence that the value ofψN total cross section must be larger than what is inferred from the use of naive vector dominance in photoproduction. 相似文献
14.
Let H=−Δ+V be a two dimensional Schr?dinger operator with a real potential V(x) satisfying the decay condition , δ > 6. Let H
0=−Δ. We show that the wave operators are bounded in L
p
(R
2) under the condition that H has no zero resonances or bound states. In this paper the condition , imposed in a previous paper (K. Yajima, Commun. Math. Phys. 208, 125–152 (1999)), is removed.
Received: 13 September 2001 / Accepted: 15 October 2001 相似文献
15.
Ji Xiaobin 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):672-675
The report includes the new observation of X(1835) in J/ψ→γη
′
π
+
π
-, the ωφ threshold enhancement in J/ψ→γωφ, the ωω structure in J/ψ→γωω and the broad 1- structure at the low K
+
K
- invariant-mass spectrum in J/ψ→K
+
K
-
π
0. 相似文献
16.
In order to remove some of the unsatisfactory features of the GIM model, we consider15-admixture in SU(4). ΔC=±ΔS decays remain unaffected. Lee-Sugawara sum-rule is obtained.15-admixture is extended then to63-admixture in SU(8). The most general Hamiltonian (H
w∼63⊕720⊕1232) in SU(8) is found to give Lee-Sugawara relation and Σ+
+=0 forS-wave decays of uncharmed baryons. Decay amplitude relations for ΔC=−1, ΔS=0 mode are obtained. 相似文献
17.
Amorphous structure generated by mechanical alloying (MA) is often used as a precursor for generating nanocomposites through
controlled devitrification. The amorphous forming composition range of ternary Al-Ni-Ti system was calculated using the extended
Miedema’s semi-empirical model. Eleven compositions of this system showing a wide range of negative enthalpy of mixing (−ΔH
mix) and amorphization (−ΔH
amor) of the constituent elements were selected for synthesis by MA. The Al88Ni6Ti6 alloy with relatively small negative ΔH
mix (−0.4 kJ/mol) and ΔHamor (−14.8 kJ/mol) became completely amorphous after 120 h of milling, which is possibly the first report of complete amorphization
of an Al-based rare earth element free Al-TM-TM system (TM = transition metal) by MA. The alloys of other compositions selected
had much more negative ΔHmix and Hamor; but they yielded either nanocomposites of partial amorphous and crystalline structure or no amorphous phase at all in the
as-milled condition, evidencing a high degree of stability of the intermetallic phases under the MA environment. Hence, the
negative ΔH
mix and ΔH
amor are not so reliable for predicting the amorphization in the present system by MA 相似文献
18.
The difference of the energies of levels Δ
n
= E
lev(2+0
n
) − E
lev(0+0
n
) at n = 1, 2, and 3 and the multipole-mixture parameter δ for (2+02−2+01) and (2+03−2+01) transitions are contrasted against the structure of the K
π
= 02+ and 03+ rotational bands that was calculated on the basis of the quasiparticle-phonon model. The values of (Δ2 − Δ1), (Δ3 − Δ1), and (Δ2 − Δ3) are found to correlate with the sign of the parameter δ and with the calculated structure of the K
π
= 02+ and 03+ bands.
Original Russian Text ? A.M. Demidov, L.I. Govor, V.A. Kurkin, I.V. Mikhailov, 2009, published in Yadernaya Fizika, 2009,
Vol. 72, No. 2, pp. 236–240. 相似文献
19.
We obtain bounds for the spectrum and for the total width of the spectral gaps for Jacobi matrices on ℓ2(ℤ) of the form (Hψ)
n
=a
n−1
ψ
n−1
+b
nψ
n
+a
nψ
n+1
, where a
n=a
n+q
and b
n=b
n+q
are periodic sequences of real numbers. The results are based on a study of the quasimomentum k(z) corresponding to H. We consider k(z) as a conformal mapping in the complex plane. We obtain the trace identities which connect integrals of the Lyapunov exponent
over the gaps with the normalised traces of powers of H.
Received: 17 April 2002 / Accepted: 1 October 2002 Published online: 13 January 2003
Communicated by B. Simon 相似文献
20.
J. Junkersfeld A. V. Anisovich G. Anton R. Bantes O. Bartholomy R. Beck Yu. Beloglazov R. Bogendörfer R. Castelijns V. Crede A. Ehmanns J. Ernst I. Fabry H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. Gridnev E. Gutz St. Höffgen I. Horn J. Hößl H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. Novinski M. Ostrick H. van Pee A. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(3):365-372
Differential and total cross-sections for photoproduction of γp→pπ
0
ω and γp→Δ
+
ω were determined from measurements of the CB-ELSA experiment, performed at the electron accelerator ELSA in Bonn. The measurements
covered the photon energy range from the production threshold up to 3GeV. 相似文献