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1.
V. S. Pavlovich 《Journal of Applied Spectroscopy》2006,73(3):328-339
A detailed derivation is presented for relations making it possible to describe the effect of temperature on the halfwidth
of the P960 and P870 absorption bands and also on the electron transfer (ET) rate at reaction centers (RCs) of the purple
bacteria Rps. viridis and Rb. sphaeroides. Primary electron transfer is considered as a resonant nonradiative transition between
P* and P+B
L
−
states (where P is a special pair, BL is an additional bacteriochlorophyll in the L branch of the reaction center). It has been shown that the vibrational hα mode with frequency 130–150 cm−1 controls primary electron transfer. It has been found that the matrix element of the electronic transition between the states
P* and P+B
L
−
is equal to 12.7 ± 0.9 and 12.0 ± 1.2 cm−1 for Rps. viridis and Rb. sphaeroides respectively. The mechanism is discussed for electron transport from P* and BL and then to bacteriopheophytin HL.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 294–303, May–June, 2006. 相似文献
2.
Y. H. Zhang T. Hayakawa M. Oshima Y. Toh J. Katakura Y. Hatsukawa M. Matsuda N. Shinohara T. Ishii H. Kusakari M. Sugawara T. Komatsubara 《The European Physical Journal A - Hadrons and Nuclei》2000,8(4):439-442
High spin states in 178Ir have been studied via the 152Sm(31P, 5nγ)178Ir reaction through excitation functions, X-γ and γ-γ-t coincidence measurements. According to the band structure characteristics
and the measured intraband B(M1)/B(E2) ratios, two rotational bands are identified and assigned to be associated with the πh
9/2⊗νi
13/2 and πh
11/2⊗νi
13/2 configurations, respectively. Both bands show the signature inversion feature.
Received: 23 March 2000 / Accepted: 31 July 2000 相似文献
3.
31P nuclear magnetic resonance (NMR) shifts on the order of thousands of parts per million are observed for olivine LiMPO4 (M = Mn, Fe, Co, Ni) samples, a promising class of Li ion rechargeable battery electrode materials. Variable-temperature
31P NMR measurements of shift are used to determine that the supertransferred hyperfine interaction is the dominant mechanism
giving rise to these unusually large observed 31P shifts. Various models for predicting 31P and 7Li shifts in LiMPO4 (M = Mn, Fe, Co, Ni) were investigated. Alloys of LiFe1−x
Mn
x
PO4, where x varies from 0 to 1, were also investigated by 7Li NMR. Covalency constants, calculated from variable-temperature NMR shifts and magnetic susceptibility data, are determined
for the P–O–M bonds in LiMPO4 (M = Mn, Fe, Co, Ni) and compared to the covalency constants of the Li–O–M bond. The sign and relative magnitude of the covalency
constants are discussed in terms of positive and negative spin densities at the nuclei of interest. The covalency constants
for the Li–O–M and P–O–M bonds were measured for Li1.8Na0.2FeMn2(PO4)3 and compared to the covalency constants measured in the olivine LiMPO4 (M = Mn, Fe, Co, Ni) samples. The Li1.8Na0.2FeMn2(PO4)3 structure has a volume per transition metal atom and Li–O–M bond distances that are similar to those of the olivine LiMPO4 (M = Mn, Fe, Co, Ni) samples.
Authors' address: Jeffrey A. Reimer, Department of Chemical Engineering, University of California Berkeley, Berkeley, CA 94720,
USA 相似文献
4.
T. Hayakawa M. Oshima Y. Hatsukawa J. Katakura H. Iimura M. Matsuda N. Shinohara Y. Toh S. Mitarai T. Shizuma M. Sugawara H. Kusakari 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):153-156
The in-beam spectroscopy on N = 91 isotones has been carried out using the 12C + 150Nd reaction. The νi
13/2 and νh
11/2 bands of 153Sm have been extended up to 33/2+ and 31/2-, respectively. Two new γ-rays have been located on the top of the unfavored band with νi
13/2 configuration in 157Dy. Two identical relationships have been established in the low-spin region of the yrast νi
13/2 configuration between 153Sm and 155Gd, and between unfavored bands of 155Gd and 157Dy. Here all these nuclei have the same neutron number N = 91.
Received: 28 June 2000 / Accepted: 20 October 2000 相似文献
5.
Novel poly(oxyethylene phosphate) tris(β-diketonate) europium (III) complexes have been synthesized by an improved procedure
using the Atherton–Todd reaction conditions. N-ethyldiisopropylamine has been used as a mild base and propylene oxide as an
acid scavenger in order to obtain poly(oxyethylene phosphate) in yield and purity higher than those achieved by conventional
methods. The compounds have been characterized by 1H, 13C, and 31P NMR and FTIR techniques. Their absorption, fluorescent excitation and emission spectra of chloroform and abs. ethanol solutions
have been recorded and studied. The luminescent quantum yields and decay times have been determined and a dependence on the
length of the oxyethylene spacer between phosphate groups has been established. The new polymer complexes are water soluble
and have increased luminescence decay time in comparison with corresponding ternary complexes. 相似文献
6.
S. Heinz E. Berdermann F. Heine O. Joeres P. Kienle I. Koenig W. Koenig C. Kozhuharov U. Leinberger M. Rhein A. Schröter H. Tsertos 《The European Physical Journal A - Hadrons and Nuclei》1998,1(1):27-37
We present the results of a Doppler-shift correction to the measured e+e−–sum-energy spectra obtained from e+e−–coincidence measurements in 238U +206Pb and 238U +181Ta collisions at beam energies close to the Coulomb barrier, using an improved experimental setup at the double-Orange spectrometer
of GSI. Internal-Pair-Conversion (IPC) e+e− pairs from discrete nuclear transitions of a moving emitter have been observed following Coulomb excitation of the 1.844
MeV (E1) transition in 206Pb and neutron transfer to the 1.770 MeV (M1) transition in 207Pb. In the collision system 238U +181Ta, IPC transitions were observed from the Ta-like as well as from the U-like nuclei. In all systems the Doppler-shift corrected
e+e−–sum-energy spectra show weak lines at the energies expected from the corresponding γ–ray spectra with cross sections being
consistent with the measured excitation cross sections of the γ lines and the theoretically predicted IPC coefficients. No
other than IPC e+e−–sum-energy lines were found in the measured spectra. The transfer cross sections show a strong dependence on the distance
of closest approach (Rmin), thus signaling also a strong dependence on the bombarding energy close to the Coulomb barrier.
Received: 22 July 1997 / Revised version: 15 October 1997 相似文献
7.
V.K.B. Kota U. Datta Pramanik 《The European Physical Journal A - Hadrons and Nuclei》1998,3(3):243-253
The SUBFF(3) dynamical symmetry limits of interacting boson – fermion – fermion model are identified and they are appropriate for heavy
deformed odd – odd nuclei for configurations with both the odd proton and odd neutron occupying all the natural parity orbits
in the corresponding valence shells. There are three symmetry limits and their correspondence with two quasi-particle (proton-neutron)
Nilsson configurations is established; one of the limits mixes both Nilsson nz's and Λ's and other two limits mix only Nilsson Λ's. The 191Ir (d,t) 190Ir single nucleon transfer spectroscopic strengths are well described by one of the symmetry limits that mixes only Nilsson
Λ's.
Received: 22 June 1998 相似文献
8.
D. A. Rudakov V. I. Potkin A. N. Ryabtsev I. B. Sivaev 《Journal of Applied Spectroscopy》2006,73(4):616-619
In the 11B NMR spectra of dihalo derivatives of bis(dicarbollyl)cobalt(III), we have identified a correlation between the 11B NMR chemical shifts of substituted boron atoms and boron atoms found in other positions on the carborane skeleton. We have
observed an increased shielding effect for fluorine atoms (compared with other halogens), manifested in an upfield shift of
the 11B NMR signals for antipodal and trans boron atoms. For the fluorine-containing compound Bu4N+ [8,8′-F2-3,3′-Co(1,2-C2B9H10)2]−, we propose the following sequence of electron density transfer: B(8) → {B(6) and B(10)} → B(4, 7).
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 547–549 (cont.), July–August, 2006. 相似文献
9.
L. Spindler I. Drevenšek Olenik M. Čopič R. Romih J. Cerar J. Škerjanc P. Mariani 《The European physical journal. E, Soft matter》2002,7(1):95-102
Self-assembling properties of deoxyguanosine 5'-monophosphate in isotropic solutions of concentrations from 0.5 wt% to 15
wt% were investigated by dynamic light scattering (DLS) and 31P NMR spectroscopy. A slow diffusive mode with a diffusion coefficient D
slow∼ 10-12 m2/s was detected by DLS for the whole concentration range. This mode is assigned to the translational motion of large globular
aggregates, similar to those observed in DNA and other polyelectrolyte solutions. The existence of such aggregates was confirmed
by freeze fracture electron microscopy. Close to the isotropic-cholesteric phase transition, at 4 wt%
c
10 wt%, also a faster diffusive mode is observed in the polarized DLS response and a very fast mode is detected by depolarized
DLS. These modes are related to translational and rotational diffusion of the columnar stacks of guanosine molecules, which
are favorably formed in the relatively narrow pretransitional region. The stacking was also revealed from the appearance of
a secondary resonance line in the 31P NMR spectra. Using the hydrodynamic theory of Tirado and Garcia de la Torre, the length of the cylindrical stacks was found
to be L = 364±78 ?, which is significantly larger than the values reported for other guanosine derivatives.
Received 13 July 2001 and Received in final form 17 October 2001 相似文献
10.
We have found that it is possible to enhance the luminescence of Pr(III) in solutions of complexes with β-diketones: acetylacetone
derivatives containing fluoroalkyl substituents of different lengths and structures. We have established that in the presence
of organic solvents, second (additional) ligands, and surfactants shielding the central ion from the quenching effect of the
water molecules (OH oscillators), the intensity of luminescence for Pr(III) increases by a factor of 65, 38, and 45 respectively.
In this case, cationic surfactants form ionic associates with Pr(III) β-diketonates, with incorporation of one more β-diketone
molecule (ratio Pr:β-diketonate:surfactant = 1:4:1). As a result of suppression of intramolecular energy losses in solutions
of Pr(III) β-diketonates, it is possible to observe its rather intense luminescence at 605 nm (the transition 1D2 → 3H4), 612 nm (3P0 → 3H6), and 646 nm (3P0 → 3F2).
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 746–750, November–December, 2006. 相似文献
11.
V. Bernard N. Kaiser Ulf-G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》1999,4(3):259-275
We evaluate the threshold matrix–element for the reaction pp→ppπ0 in a fully relativistic Feynman diagrammatic approach. We employ a simple effective range approximation to take care of the
S–wave pp final–state interaction. The experimental value for the threshold amplitude A = (2.7 −i0.3) fm4 can be reproduced by contributions from tree level chiral (long–range) pion exchange and short–range effects related to vector
meson exchanges, with ω-exchange giving the largest individual contribution. Pion loop effects appear to be small. We stress
that the commonly used heavy baryon formalism is not applicable in the NN–system above the pion production threshold due to
the large external momentum, |p|≃ (Mm
π)−1/2, with M and m
π the nucleon and the pion mass, respectively. We furthermore investigate the reaction pp→pnπ+ near threshold within the same approach. We extract from the data the triplet threshold amplitude as B = (2.8 −i1.5) fm4. Its real part can be well understood from (relativistic) tree level meson–exchange diagrams. In addition, we investigate
the process pp→ppη near threshold. We use a simple factorization ansatz for the ppη final–state interaction and extract from the data the modulus of the threshold amplitude, |C|= 1.32 fm4. With g
ηN= 5.3, this value can be reproduced by (relativistic) tree level meson–exchange diagrams and η–rescattering, whose strength
is fixed by the ηN scattering length. We also comment on the recent near threshold data for η′–production.
Received: 27 November 1998 相似文献
12.
S.K. Katoch S.L. Gupta S.C. Pancholi D. Mehta S. Malik G. Shanker L. Chaturvedi R.K. Bhowmik 《The European Physical Journal A - Hadrons and Nuclei》1999,4(4):307-309
High-spin states in the odd-odd 168Lu nucleus, populated in the 154Sm(19F,5n) reaction at a beam energy of 96 MeV, were investigated using in-beam γ-ray spectroscopy techniques. The BC neutron crossing
in the yrast band, based on πg
7/2[404]7/2+⊗νi
13/2[642]5/2+ configuration, occurs at ħω= 0.31 MeV. The two side bands, based on πh
11/2[514]9/2−⊗νi
13/2[642]5/2+ and πh
9/2[541]1/2−⊗νi
13/2[642]5/2+ configurations, show anomalous signature-splitting and signature-inversion in the first one, to occur at ħω= 0.24 MeV. A
moderately delayed BC-crossing is anticipated in the second one.
Received: 15 June 1998 / Revised version: 11 January 1999 相似文献
13.
A new solid substrate-room temperature phosphorescence (SS-RTP) method for the determination of trace manganese (II) has been
established. It bases on the fact that fullerol (R) emits strong and stable room temperature phosphorescence (RTP) on filter
paper substrate. H2O2 can oxidize R to cause the SS-RTP quenching. But manganese (II) can obstruct H2O2 to oxidize R, and enhance the RTP of R. α,α′-Bipyridine (Bipy) can sensitize the RTP. After adding Bipy, the ΔI
p enhances 7 times than that without Bipy. Under the optimum conditions, the linear dynamic range of this method is 0.016–1.12 pg spot−1 with a detection limit (L.D.) of 4.6 fg spot−1 ( is the absolute mass of Mn2+), and the regression equation of working curve is ΔI
p=25.20 + 63.55 (pg spot−1), n=6, r=0.9983. For 0.016 and 1.12 pg spot−1 Mn2+, RSDS are 4.3 and 4.8%, respectively (n=7). This method has been applied to the determination of trace manganese (II) in actual sample with high sensitivity and
good selection. And the reaction mechanism of SS-RTP is discussed. 相似文献
14.
G.A. Chass S. Lovas R.F. Murphy I.G. Csizmadia 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):481-497
An exhaustive ab initio and DFT search for energetically stable conformers from the topologically possible set was undertaken on the N-acetyl-phenylalanyl-N-methylamide
and N-acetyl-tyrosyl-N-methylamide systems. The geometries of all 81 phenylalanyl and 162 tyrosyl possible rotamers, described
under the rules outlined by Multi-Dimensional Conformational Analysis (MDCA), were attempted at each of the RHF/3-21G, RHF/6-31G(d)
and B3LYP/6-31G(d) levels of theory. A total of 32 and 66 stable conformational minima were found for the phenylalanyl and
tyrosyl amino acid diamides, respectively, at the B3LYP/6-31G(d) level. From the tyrosyl set, 33 unique conformers emerge
when the orientation of the A
i
3
dihedral angle (p-OH orientation) is disregarded. A total of 31 conformers were common to both sets and showed nearly identical geometries.
The comparison of the optimized DFT geometries of the two systems showed near by perfect linear fits with R2 values of 0.9997, 0.9994, 0.9997, and 0.9996 for the φ
i
, ψ
i
, A
i
1
, and A
i
2
dihedral angles, respectively. Relative energies of the matching 31 conformers also fitted to a linear plot with an R2 value of 0.9985. The geometric centroid of the aromatic ring in the sidechain of both systems was found to be within 4.1
?of the H and O atoms of the peptide groups, in 21 and 2 of the conformers, respectively. None of the non-matching conformers
showed any such interaction distance ≤4.1 ?.
Received 1st February 2002 / Received in final form 28 May 2002 Published online 13 September 2002 相似文献
15.
J. Becker H.G. Andresen J.R.M. Annand K. Aulenbacher K. Beuchel J. Blume–Werry Th. Dombo P. Drescher M. Ebert D. Eyl A. Frey P. Grabmayr T. Großmann P. Hartmann T. Hehl W. Heil C. Herberg J. Hoffmann J.D. Kellie F. Klein K. Livingston M. Leduc M. Meyerhoff H. Möller Ch. Nachtigall A. Natter M. Ostrick E.W. Otten R.O. Owens S. Plützer E. Reichert D. Rohe M. Schäfer H. Schmieden R. Sprengard M. Steigerwald K.-H. Steffens R. Surkau Th. Walcher R. Watson E. Wilms 《The European Physical Journal A - Hadrons and Nuclei》1999,6(3):329-344
The electric form factor of the neutron GEn has been determined in double polarized exclusive 3
He(e,e'n) scattering in quasi–elastic kinematics by measuring asymmetries A
⊥, A
∥ of the cross section with respect to helicity reversal of the electron, with the nuclear spin being oriented perpendicular
to the momentum transfer q in case of A⊥ and parallel in case of A∥. The experiment was performed at the 855 MeV c. w. microtron MAMI at Mainz. The degree of polarization of the electron beam
and of the gaseous 3
He target were each about 50%. Scattered electrons and neutrons were detected in coincidence by detector arrays covering large
solid angles. Quasi–elastic scattering events were reconstructed from the measured electron scattering angles ϑe, φe and the neutron momentum vector p
n
′ in the plane wave impulse approximation. We obtain the result <G
En>(0.27 < Q2c2/GeV2 < 0.5)= 0.0334 ± 0.0033stat± 0.0028syst which is averaged over the indicated range of Q
2, the squared momentum transfer. This G
En value is significantly smaller than measured from the D(e,e'n) reaction under similar kinematical conditions. To what extent final state interactions in 3He quench the G
En result is subject of calculations currently in progress elsewhere.
Received: 29 April 1999 相似文献
16.
I. Bakonyi P. Bánki K. Tompa H. Ebert W. Socher J. Voitländer 《Hyperfine Interactions》1989,51(1-4):1019-1024
The11B and31P NMR Knight shift (K) and Korringa spin-lattice relaxation rate (1/T
1
T) have been measured for amorphous Ni81.5B18.5−x
P
x
alloys with 0≤x≤18.5. In accordance with previous bulk measurements, the31P NMR parameters vary markedly with composition whereas the11B NMR parameters remain almost constant except for small P-contents. It is suggested that the d-band contribution toK(31P) is positive and that toK(11B) is negative. The data further support our previous conclusion that amorphous Ni81.5B18.5 is a Pauli paramagnet rather than a weak itinerant ferromagnet. 相似文献
17.
J. Mrázek M. Honusek A. Špalek J. Bielčík J. Slívová J. Adam A.A. Pasternak 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):399-408
The results of in-beam investigations of excited states of 99Ru using the 98Mo(α,3n) reaction are presented. Angular distributions of γ–rays and γ–γ coincidences have been measured. Excited states have
been identified up to an energy of E = 5603 keV and spin of Iπ= 31/2−. Mean lifetimes τ have been determined using the DSA method for eleven levels. Aligned angular momenta are discussed and
the probable (νh
11/2) origin of a backbending at frequency about 0.5 MeV was confirmed. The possible role of (νd
5/2) alignment at frequencies above 0.5 MeV was pointed out.
Received: 13 January 1999 / Revised version: 26 March 1999 相似文献
18.
Lei Gao Yanyan Huang 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(2):165-171
The effective linear and nonlinear optical properties of metal/dielectric composite media, in which ellipsoidal metal inclusions
are distributed in shape, are investigated. The shape distribution function P(L
x, L
y) is assumed to be 2Δ-2θ(L
x - 1/3 + Δ/3)θ(L
y - 1/3 + Δ/3)θ(2/3 + Δ/3 - L
x - L
y), where θ( . . . ) is the Heaviside function, Δ is the shape variance and Li are the depolarization factors of the ellipsoidal inclusions along i-symmetric axes (i = x, y). Within the spectral representation, we adopt Maxwell-Garnett type approximation to study the effect of shape variance Δ
on the effective nonlinear optical properties. Numerical results show that both the effective linear optical absorption α
∼ ωIm() and the modulus of the effective third-order optical nonlinearity enhancement |χ(3)
e|/χ(3)
1 exhibit the nonmonotonic behavior with Δ. Moreover, with increasing Δ, the optical absorption and the nonlinearity enhancement
bands become broad, accompanied with the decrease of their peaks. The adjustment of Δ from 0 to 1 allows us to examine the
crossover behavior from no separation to large separation between optical absorption and nonlinearity enhancement peaks. As
Δ → 0, i.e., the ellipsoidal shape deviates slightly from the spherical one, the dependence of |χ(3)
e|/χ(3)
1 on Δ becomes strong first and then weak with increasing the imaginary part of inclusions' dielectric constant. In the dilute
limit, the exact formula for the effective optical nonlinearity is derived, and the present approximation characterizes the
exact results better than old mean field one does.
Received 10 December 2002 Published online 4 June 2003
RID="a"
ID="a"e-mail: lgaophys@pub.sz.jsinfo.net 相似文献
19.
The field dependence of the nuclear spin-lattice relaxation (SLR) of cold implanted 82Br (T ≤ 25 mK) in α-Fe single crystals was investigated with nuclear magnetic resonance of oriented nuclei (NMR/ON) at low temperatures
as experimental technique. The SLR at the lattice sites with the hyperfine fields found by earlier NMR/ON experiments was
measured as a function of the applied external magnetic field B
ext parallel to the three principle axes [100], [110] and [111] of the iron single crystal. The data were evaluated with the
full relaxation formalism in the single impurity limit and for comparison also with the often employed model of a single exponential function with an effective relaxation time
T
1′. With a phenomenological model the high field values of the relaxation rates r
∞, [100]′ = 6.6(2) · 10−15 T2sK−1, r
∞, [110] = 5.4(2) · 10−15 T2sK−1 and r
∞, [111] = 5.2(1) · 10−15 T2sK−1 were obtained. 相似文献
20.
E. Z. Utyanskaya B. V. Lidskii M. G. Neigauz A. E. Shilov 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(6):884-895
It was shown earlier that the hydrolysis of the (CuATP2−)2 dimeric complex to CuADP− and inorganic phosphate P
i
was an irreversible reaction. The main intermediate hydrolysis product, the formation of which should be taken into account
at comparatively early hydrolysis stages, was the IntK pentacovalent intermediate. It was formed in parallel with hydrolysis
to CuADP− and P
i
through the common intermediate product (CuATP2−)2OH− — DOH−. We studied the influence of the addition of various concentrations of Mg2+ ions to the reaction mixture at pH 7.1–7.2, a range for which the kinetics of hydrolysis is sensitive to the rate constants
of deactivation of DOH− active centers (conjugated with CuADP− formation and occurring via the formation of IntK). The conversion of ATP above which stationary hydrolysis regime was observed
decreased as the concentration of Mg2+ grew. The DOH−
$
\underset{{OH^ - }}{\overset{{OH^ - }}{\longleftrightarrow}}$
\underset{{OH^ - }}{\overset{{OH^ - }}{\longleftrightarrow}}
IntK equilibrium according to the conversion of ATP was established more rapidly, and it was to a greater extent shifted toward
IntK. It was assumed that hydrated Mg2+ linked as a second metal ion with ATP β and γ phosphate groups hydrated IntK much stronger than DOH−. The Cu · OH2 · AMP complex played the role of a common acid catalyst and hydrated DOH− better than Mg2+ · OH2. The selective hydration of DOH− by the CuOH2 · AMP complex at early hydrolysis stages directed the process toward the formation of IntK, which caused the appearance of
an induction period in the formation of CuADP−. 相似文献