共查询到20条相似文献,搜索用时 31 毫秒
1.
S. Cohen M. Aymar A. Bolovinos M. Kompitsas E. Luc-Koenig H. Mereu P. Tsekeris 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):165-180
The even parity 5
pnpJ
= 0, 1 and 2 doubly excited autoionizing states of strontium were investigated both experimentally and theoretically. Sr atoms
in an atomic beam were excited through the two-step Isolated Core Excitation (ICE) scheme 5s2
1
S
0
-λ
1
→ 5
sn'p
1
P
1
(
n'
= 12-16)-λ
2
→ [5
p
3/2
np
]
J
. The final ICE transition probes the [5
p
3/2
np
]
J
resonances. However, the [5
p
1/2
np
]
J
series below the 5
p
1/2
threshold were excited also due to their mixing with the [5
p
3/2
np
]
J
perturbers. An extended energy region was covered below and above the 5
p
1/2
ionization limit by saturating the central ICE lobe and recording as many as possible “red” and “blue” secondary lobes. J identification was achieved by using mutually parallel and perpendicular linear polarizations of the laser beams. The ICE
spectra were compared to those obtained by employing a two-step excitation scheme using the bound 4
d
5
p
1
P
1
valence state as an intermediate one. Final identification for very complex structures was achieved after comparison with
theoretical energy level positions and excitation profiles produced by the R-matrix method combined with the multichannel quantum defect theory (MQDT) method. The agreement between theoretical and observed
structures is quite satisfactory.
Received 31 May 2000 相似文献
2.
Reduction of substituted benzophenones 1 with sodium borohydride and trifluoro-acetic acid yields diphenylmethanes 3 as well as dimers 5 and 6. the complete structure of these substituted diphenylmethane dimers 5 may be accurately determined by 1H, 13C, 2D NMR analysis, and a mechanism for their formation is suggested. 相似文献
3.
Jean-Jacques Aaron Mounir Maafi Christophe Kersebet Cyril Parkanyi Maged Shafik Antonious Noboru Motohashi 《光谱学快报》2013,46(7):1111-1122
The room temperature (298 K) electronic absorption, and fluorescence excitation and emission spectra of seven new, pharmacologically-important benzo[a]phenothiazines (12H-benzo[a]phenothiazine ( 1 ), 9-methyl-12H-benzo[a] phenothiazine ( 2 ), 10-methyl-12H-benzo[a] phenothiazine ( 3 ), 11-methyl-12H-benzo[a]phenothiazine ( 4 ), 5-oxo-5H-benzo[a]phenothiazine ( 5 ), 6-hydroxy-5-oxo-5H-benzo[a]phenothiazine ( 6 ) and 6-methyl-5-oxo-5H-benzo[a] phenothiazine ( 7 ):) were measured in several solvents of different polarities and hydrogen bonding abilities. In combination with the ground state dipole moments of these benzo[a]phenothiazines, the spectral data were used to determine their first excited singlet-state dipole moments by means of the solvatochromic shift method. These excited singlet-state dipole moments were found to be significantly higher (1.9 to 2.5 Debye units) than their ground-state counterparts. 相似文献
4.
R. Ashby J.J. Clarke W.A. van Wijngaarden 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):327-331
6Li 32D
3/2, 5/2
states were studied using a diode laser to first excite the 2P
3/2
state and a dye laser to populate the 32D
3/2, 5/2
states. The dye laser was modulated by an electro-optic modulator and intersected an atomic beam that passed through a field
free region and subsequently through a uniform electric field. A value of 1084.24±0.20 MHz was found for the 32D fine structure splitting. The scalar and tensor polarizabilities were determined to be α
(3D
3/2
) = - 3.753±0.015, α
2
(3D
3/2
) = 2.893±0.017, α
(3D
5/2
) = - 3.772±0.008 and α
2
(3D
5/2
) = 4.058±0.013 MHz/(kV/cm)2.
Received 26 September 2002 / Received in final form 22 January 2003 Published online 11 March 2003
RID="a"
ID="a"e-mail: wlaser@yorku.ca 相似文献
5.
《光谱学快报》2013,46(4-5):521-537
Abstract Proton and carbon‐13 NMR data are presented for 5‐methoxytryptamine, 1; 6‐methoxytryptamine, 2; N,N‐diisopropyl‐5‐methoxytryptamine, 3, (5‐MeO‐DIPT); and N,N‐diisopropyl‐5‐methoxyindole‐3‐glyoxylamide, 4, at 300 MHz (1H) and 75 MHz (13C) in CDCl3 at ambient temperature. Compound 3, considered a potential hallucinogen, had been placed into Schedule I of the Controlled Substances Act, effective April 4, 2003, by the U.S. Drug Enforcement Administration. Compound 4 can serve as a possible precursor to 3. We believe that these are the first proton NMR assignments obtained at medium field (7 tesla) using selective homodecoupling and two‐dimensional homonuclear chemical shift correlation spectra (using one or more of the COSY45, COSY90, and COSYLR experiments) for rigorous aryl proton assignments in this group of compounds. Significant observed differences in the proton and carbon‐13 NMR spectra should allow facile distinction of the 5‐methoxy series, 1 and 3, from the 6‐methoxy series, 2. Energy minimizations to obtain optimized structures for each compound were performed at the Hartree–Fock level with the 6‐31G* basis set, and the resulting geometries are discussed. The presented geometry calculations appear to be the most accurate reported to date for 1 based on the basis set employed, and the first HF/6‐31G* structures for compounds 2, 3, or 4. Appreciable geometry differences in 3 and 4 for the pendant sidechain containing the N[CH(CH3)2]2 moiety are noteworthy. Proximity of the carbonyl oxygens in 4 to H2 and H4 is suggested as a possible contributing factor in the deshielding of these protons in the NMR spectrum. 相似文献
6.
《光谱学快报》2013,46(4):367-381
Abstract New polyether ligands of Schiff base type (3–13) were synthesized from the reaction of diethylene glycol bis(2‐aminophenyl)ether and triethylene glycol bis(2‐aminophenyl)ether with salicylaldehyde, 5‐methoxysalicylaldehyde, 5‐bromosalicylaldehyde, 5‐nitro salicylaldehyde, and 2‐hydroxy‐1‐naphthaldehyde. The products were characterized by elemental analysis, IR, 1H, 13C NMR, and UV‐VIS techniques. The UV‐VIS spectra of those Schiff bases with an OH group in the ortho position to the imino group were studied in polar and nonpolar solvents in acidic and basic media. The compounds are in tautomeric equilibrium (enol‐imine, O–H · N?keto‐amine, O · H–N forms) in solvents, acidic chloroform, and benzene solutions and basic DMSO, chloroform, and benzene solutions. These tautomers were not observed in polar and non‐polar solvents and in basic solutions of DMSO, chloroform, and benzene for the Schiff bases 5–10. Tautomer proportions, which were obtained from 1H NMR and UV‐VIS data in DMSO, were compared for compounds 3, 4, 11, and 12. 相似文献
7.
Results of ir and Raman investigations on trigonal layer-structured Si2Te3 single crystals are reported. The ir reflection spectrum withEc exhibits seven reststrahl-like bands, whereas the corresponding spectrum withEc shows only one very small bump. Values for
0 and
are given. The Raman spectra are very rich in structure and can only be interpreted qualitatively as being a mixture of single phonon lines and one- and two-phonon density-of-states contributions. One-phonon density-of-states effects are disorder-induced owing to the statistical occurrence of the Si atoms within the regular hexagonal Te sublattice. 相似文献
8.
Abstract Reaction of 2-aminothiazoline with an aromatic aldehyde and diethylmalonate, in basic medium afforded two kinds of regioisomers: 5-oxo and 7-oxo-tetrahydrothioazolopyrimidines. Assignment of the structures of 5-oxo-7-phenyl-2,3,6,7-tetrahydro-5H -thiazolo[3,2-a] pyrimidine-6-ethylcarboxylate (1) and 7-oxo-5-phenyl-2,3,5,6-tetrahydro-7H -thiazolo[3,2-a] pyrimidine-6-ethylcarboxylate (2) were performed using 1H and 13C NMR spectroscopy, including NOE experiments. For each regioisomer, only R?S? trans-diaxial diastereoisomers were isolated and characterized. 相似文献
9.
H. Zheng Y. Wang G. Ma 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):61-69
The electronic structure of LaNi5 and its hydride LaNi5H7 are obtained using the self-consistent cluster-embedding calculation method. The Fermi level of LaNi5H7 is 5.172 eV higher than that of LaNi5. In both materials, the La 5d electrons locate nearby the Fermi levels, and make only a small contribution to the density of states (DOS) of the valence
bands. There is no significant charge transfer from La to Ni in LaNi5. But for LaNi5H7, there is a charge transfer of 1.16 electrons from La to H, and H atoms are combined mainly with Ni to form hybridized orbitals
in the energy regions far below the Fermi level. An explanation of hydrogenation of LaNi5 is proposed: It is easy for hydrogens to take off some localized La 5
d electrons near the Fermi level, and combine with Ni to form hybridized orbitals in lower energy regions. This process is
therefore in favor of energy, and forces a lattice expansion until the Fermi level rises to zero.
Received 13 July 2001 / Received in final form 10 December 2001 Published online 17 September 2002 相似文献
10.
Szommer T Lukács A Kovács J Szabó MJ Hoffmann MG Schmitt MH Gerencsér J 《Molecular diversity》2012,16(1):81-90
Abstract
An efficient and convenient solution-phase synthesis of a 1H-1,2,4-triazole library with potential agrochemical activity is reported employing microwave-assisted organic synthesis (MAOS) and continuous-flow microfluidic synthetic methods starting from commercially available 3,5-dibromo-1H-1,2,4-triazole (1). MAOS was used for the synthesis of 5-amino-3-bromo-1,2,4-triazole analogs 3 and for their 3-aryl derivatives 4 via Suzuki–Miyaura coupling with polymer-supported catalyst. A microfluidic hydrogenation reactor integrated into an automated parallel synthesis platform was built and utilized for the reductive dehalogenation reactions providing 5-aminotriazoles (5). 相似文献11.
Pyrazolo[3,4-b]pyridines having 4-chloro-5-chloroethyl side chain are synthesized by the reaction of 5-aminopyrazole and cyclic β-formylester
gave aminopyrazolodihydrofuranone intermediate, which on cyclization in phosphorous oxychloride exclusively converted in to
4-chloro-5-chloroethyl pyrazolo[3,4-b]pyridines 4(a-b) in major amount. The side chain with acetic acid, thiourea and aromatic amines are used to form angular ring leads to formation
of tricyclic Furo[2,3-d]pyrazolo[2,3-b]pyridines 5(a-b), pyrazolo[3,4-b]thieno[2,3-d]pyridines 6(a-b) and pyrazolo[3,4-b]pyrrolo[2,3-d]pyridines 7(a-n) respectively. The substituents effect at C4 position on fluorescence properties of pyrazolopyridines has been studied. Moreover the effect of electron donor and halogen
substituents on fluorescence properties of pyrazolopyrrolopyridines 7(a-n) has been investigated along with their fluorescent quantum yield. 相似文献
12.
The complete structural analysis of 1-[(4-methoxyphenyl)-(3,4,5-trimethoxyphe- nyl)methyl]naphtalene 5a and 1-[(2,5-dimethoxyphenyl)-(3,4,5-trimethoxyphenyl) methyljnaphtalene 5b, prepared by alkylation of 1-[chloro-(3,4,5-trimethoxyphenyl) methyl]naphtalene without by-products such as benzofluorene 2, may be accurately determined by 1H, 13C NMR and 2D NMR analysis. 相似文献
13.
A. Bombardi N. Kernavanois P. Dalmas de Réotier G.H. Lander J.P. Sanchez A. Yaouanc P. Burlet E. Lelièvre-Berna A. Rogalev O. Vogt K. Mattenberger 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(4):547-552
In the UxLa1-xS system there is an abrupt loss of the long-range ferromagnetic ordering found in pure US at a critical concentration x
c
∼ 0.57, which is far above the percolation limit. As the magnetic ground state in such a system can be strongly affected by small
variations of the 5f localization, we have investigated a set of samples with different x by polarized neutron diffraction and X-ray magnetic circular dichroism (XMCD). The neutron results are consistent with early
measurements performed on pure US. Even at the lowest U content (x
= 0.15, below x
c
) the shape of the induced form factor (f
(
Q
)) is comparable with that found for x
= 1 and is well reproduced by either a U4+ or a U3+ state. The ratio between the orbital and the effective spin moments in the XMCD measurements confirms this result, but the
evolution of the shape at the M5 edge suggests an abrupt change in the distribution of the electrons (holes) in the 5
f density of states around x
c
.
Received 31 January 2001 相似文献
14.
F. Fauth E. Suard V. Caignaert B. Domengès I. Mirebeau L. Keller 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(2):163-174
The oxygen deficient cobaltites LnBaCo2O5 (Ln = Tb, Dy, Ho) exhibit two successive crystallographic transitions at T
N
∼340 K and at T
CO
∼210 K. Whereas the first transition (P4/mmm to Pmmm) is related to the long-range antiferromagnetic ordering of the Co ions
(spin ordering), the second transition (Pmmm to Pmmb) corresponds to the long-range ordering of the Co2+ and Co3+ species (charge ordering) occurring in 1:1 ratio in the structure. The charge ordered (CO) state was directly evidenced by
the observation of additional superstructure peaks using neutron and electron diffraction techniques. The CO state was also
confirmed indirectly from refinement of high resolution neutron diffraction data as well as from resistivity and DSC measurements.
From the refined saturated magnetic moment values only, ∼3.7
and ∼2.7
, the electronic configuration of the Co ions in LnBaCo2O5 remains conjectural. Two pictures, with Co3+ ions either in intermediate spin state ( t
5
2g
e
1
g
) or in high spin state ( t
4
2g
e
2
g
), describe equally well our experimental data. In both cases, the observed magnetic structure can be explained using the
qualitative Goodenough-Kanamori rules for superexchange. Finally, in contrast to the parent Ln = Y compound [Vogt et al. , Phys. Rev. Lett. 84, 2969 (2000)], we do not report any spin transition in LnBaCo2O5 (Ln = Tb, Dy, Ho).
Received 13 December 2000 相似文献
15.
Abstract The IR and Raman spectra of 1, 3, 5-trithiacyclohexane (1) and 1, 3, 5-triselenocyclohexane (2) have been recorded with FT-instrumentation within 3500–100 cm?l, and the C-S vibrations of 1 have been reviewed by comparing its spectra with those of 2. The IR and Raman spectra slightly differ from those previously reported and some vibrations, previously assigned to C-H modes in 1on the basis of NCT calculations, are reassigned to C-S modes on the basis of the selenation effect. “Selenation” has proved to be a very simple and effective tool in recognizing carbon-sulfur vibrations both in IR and Raman. The Raman peaks due to carbon-chalcogen vibrations are less intense in 1 than in 2, according to the higher polarizability of the selenium atom. 相似文献
16.
CD data of the optically active 4-hydroxy (1–5) and 4-acetoxy chromans (6–8) were analyzed by two different approaches. The Snatzke-Antus treatment of chiraly perturbed chromane chromophore revealed M absolute conformation and 4S absolute configuration of the alcohols, i.e. P absolute conformation and 4R absolute configuration of the acetates. The proposed absolute configuration of the optically active alcohols was confirmed for 1 and 2 by the chiral excitone coupling method applied on their benzoates 9 and 10. 相似文献
17.
K. Hashimoto M. Okamoto K. Takayanagi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(1):75-78
The stability of neutral, singly and multiply ionized silicon clusters, (N
= 2-7, M
= 0, , , ), has been investigated using an ab initio density functional method. We show that the fragmentation effect significantly affects the structure of mass-spectra of multiply
ionized silicon clusters. For clusters, the clusters with a large fragmentation energy are found to correspond to the high peaks at N = 4 and 6 in mass-spectra. For clusters, a peak at N = 5 in mass-spectra has been predicted to be especially high.
Received: 9 June 1997 / Revised: 8 January 1998 / Accepted: 25 February 1998 相似文献
18.
G. Durand F. Spiegelman A. R. Allouche 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):19-22
Recently, electric susceptibilities of
NanFn-1 clusters
have been measured by deflecting a molecular beam in an
inhomogeneous electric field. The analysis of the deflection of
a cluster by the electric field needs the calculation of the
electric properties. We present the calculation of the static
anisotropic and average dipolar polarizabilities within a model
in which the
NanFn-1 clusters (
2
n
23)
are treated as one electron embedded in the field of
n ions
Na+ and of n
- 1
ions F-. The accuracy of the results
is evaluated and discussed on small clusters (n
5)
in comparison with ab initio
calculations. The relationship between the polarizabilities, the
electronic localization and the geometric structure is
discussed. Received 10 September 2002 Published online 3 July
2003 相似文献
19.
Y. Kohori Y. Yamato Y. Iwamoto T. Kohara 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,18(4):601-604
We have carried out 115In nuclear quadrupole resonance (NQR) measurements in CeRhIn5. At ambient pressure, CeRhIn5 undergoes an antiferromagnetic AF phase transition at K. The 115In NQR spectrum has shown the appearance of a small internal field in the direction perpendicular to the tetragonal c-axis. With application of a hydrostatic pressure, the AF state is suppressed and the superconductivity appears just above
the critical pressure (P
= 17 kbar). The nuclear spin lattice relaxation rate 1/T1 of 115In measured at P
= 27 kbar indicates the occurrence of the superconductivity in the nearly AF region. In the superconducting state, 1/T1 has no Hebel-Slichter coherence peak just below of 2 K and has a power law T-dependence (T3) down to 300 mK. This is consistent with anisotropic superconductivity, with line nodes in the superconducting energy gap:
non-s-wave superconductivity occurs in CeRhIn5.
Received 5 July 2000 相似文献
20.
Ming-Der Su 《Molecular physics》2015,113(13-14):1590-1599
The mechanisms of the photochemical isomerisation reactions are investigated theoretically using the model systems, 1,2-dihydro-1,2-phosphaborine (5) and 1,2-dihydro-1,2-alumazaine (6), using the CAS(6,6)/6-311G(d,p) and MP2-CAS-(6,6)/6-311++G(3df,3pd)//CAS(6,6)/6-311G(d,p) methods. For each model reactant, three reaction pathways, which lead to three kinds of photo-isomers, are examined. The structures of the conical intersections, which play a key role in such photo-rearrangements, are determined. The thermal (or dark) reactions of the reactant species are also examined, using the same level of theory, to provide a qualitative explanation of the reaction pathways. These model investigations demonstrate that the preferred reaction route for these two aromatic heterocyclics is as follows: reactant → Franck–Condon region → conical intersection → photoproduct. The theoretical evidences anticipate that after irradiation of 5, the photoproduct yield of the Dewar BP-isomer, 8, should be larger than that of the Dewar BP-isomer, 7, whereas no Dewar BP-isomer 9 can be observed. Moreover, the present theoretical data predict after irradiation of 6, all three Dewar AlN-isomers (10, 11, and 12) and the starting molecule, 6, are produced. 相似文献