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1.
The fluorescence excitation spectra and polarization of the fluorescence of a bichromophore cooled in a supersonic jet are
measured. The bichromophore consists of 2,5-diphenyloxazole (PPO) and 1-(5′-phenyl-1′, 3′-oxazole-2′-yl)-4-(5′-phenyl-1′,3′,4′-oxadiazole-2′-yl)-benzene
(POPDP) connected by the methylene bridge -(CH2)-. Based on the analysis of these components and theoretical calculations, it has been proven that the total intramolecular
singlet-singlet transfer of the energy of electronic excitation from the energy donor PPO to the acceptor POPDP occurs in
a time of 10−12 sec.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 460–463, July–August, 2005. 相似文献
2.
N. G. Bryantseva I. V. Sokolova R. M. Gadirov V. P. Khilya Ya. L. Garazd 《Journal of Applied Spectroscopy》2009,76(6):813-818
Fluorescence spectra at 298 and 77 K and phosphorescence spectra at 77 K have been measured for five new compounds. Fluorescence
and phosphorescence quantum yields have been measured by comparison with a standard (8-methoxypsoralen). Phosphorescence lifetimes
at 77 K have been found for 2-hydrazyl-3,4-cyclopentyl-14,14-dimethylpryanocoumarin (1.60 msec); 2-hydrazyl-3,4-cyclohexyl-7-methoxycoumarin
(1.35); 3,4-phenyl-4′,5′-cyclohexylpsoralen (2.50); 4′-methyl-3,4-cycloheptylpsoralen (1.10); and 4′,5′-dimethyl-3,4-cyclohexylpsoralen
(1.25). The basic channel of energy deactivation for 3,4-phenyl-4′,5′-cyclohexylpsoralen; 4′-methyl-3,4-cycloheptylpsoralen;
and 4′,5′-dimethyl-3,4-cyclohexylpsoralen is radiative transfer. Energies of the lowest excited triplet states have been calculated
using an INDO/S quantum-chemical method. 相似文献
3.
Eu(III)-9-acridinecarboxylate (9-ACA) complex was synthesized and characterized by elemental analysis, conductivity measurement,
IR spectroscopy, thermal analysis, mass spectroscopy, 1H-NMR, fluorescence and ultraviolet spectra. The results indicated that the composition of this complex is [Eu(III)-(9-ACA)2(NCS)(C2H5OH)2] 2.5 H2O and the oxygen of the carbonyl group coordinated to Eu(III). The interaction between the complex with nucleotides guanosine
5′- monophosphate (5′-GMP), adenosine 5′-diphosphates (5′-ADP), inosine (5′-IMP) and CT-DNA was studied by fluorescence spectroscopy.
The fluorescence intensity of Eu(III)-9-acridinecarboxylate complex was enhanced with the addition of CT-DNA. The effect of
pH values on the fluorescence intensity of Eu(III) complex was investigated. Under experimental conditions, the linear range
was 9–50 ng mL−1 for calf thymus DNA (CT- DNA) and the corresponding detection limit was 5 ng mL−1. The results showed that Eu(III)-(9-ACA)2 complex binds to CT-DNA with stability constant of 2.41 × 104 M . 相似文献
4.
Phosphorescence decay of 3-(2′-N-methylbenzimidazolyl)-7-N, N-diethylaminocoumarin; 2,3,5,6-1H, 4H-tetrahydro-8-methylquinolizino-〈9,
9a, 1-gh〉 coumarin; 2,3,5,6-1H, 4H-tetrahydro-8-trifluormethylquinolizino-〈9,9a,1-gh〉 coumarin; 9(10H)-acridone; 9-aminocridine
hydrochloride, 1-hydrate and 2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3, 4-oxadiazole dyes in EPA glass at 77 K have been recorded
using N2 laser. The results were used to determine lifetimes. Emission intensities from the first two dyes have been examined in relation
to dye concentration and excitation intensity. The results are discussed. 相似文献
5.
A. A. Volod’kin G. E. Zaikov L. N. Kurkovskaya E. B. Burlakova 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(5):836-845
The energies of formation, enthalpies, and entropies of the conformers of 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionic acid and sodium and potassium 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionates are calculated by quantum-chemical methods in the PM6 approximation. A doubling of signals
in the 1H NMR spectrum of the first conformer is observed, which merge into singlets when the compound is heated. Changes in the structure
of the conformers and donor-acceptor complexes (solvates) occur with the preservation of the metal-ligand coordination bond.
Calculations of the characteristics of 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionic acid and sodium and potassium 1-(carboxy)-1-(N-methylamide)-2-(3′,5′-di-tert-butyl)-4-hydroxyphenyl)-propionates in the PM6 approximation make it possible to predict the structure and properties of
the solvated structures. The energies of homolysis of the H-O bond D
(OH) are calculated, and a linear dependence of the antioxidant activity on D
(OH) for the structures of the studied compounds is demonstrated. The results make it possible to predict the properties of antioxidants
in the biological environment. 相似文献
6.
7.
R. H. Compton K. T. V. Grattan T. Morrow 《Applied Physics A: Materials Science & Processing》1980,22(3):307-311
The fundamental photophysical parameters of the organic scintillators, anthracene, 9, 10 dimethyl antracene (DMA), 9, 10 diphenyl
anthracene (DPA), 2-(1-napthyl)-5-phenyloxazole (α-NPO) and 2, 2′-p-phenyl bis (5-phenyloxazole) (POPOP), were investigated
in the liquid and vapour phases. Their ground state, triplet-triplet and fluorescence spectra were determined and accurate
extinction coefficients obtained. Photodecomposition of POPOP vapour under 337 nm excitation was investigated in detail and
a photodecomposition quantum yield of 1.1×10−2 obtained at 568 K. The POPOP triplet state in the vapour phase is quenched by the addition of 1, 3, 5, 7 cyclo-octatetraene
and a quenching rate constant of 2.9×1010 M−1 s−1 was determined. 相似文献
8.
A new polymeric material for optical switching 总被引:1,自引:0,他引:1
′ -(2′′,4′′,6′′-trichlorophenazoamino)-phenazo-4-nitrobenzene, was studied. Large nonresonant optical nonlinearity (χ(3)≥10-28 C4m/J3 or
10-9 esu) and fast response time (t<20 ps) were measured by forward degenerate four-wave mixing experiment. Optical bistable behavior
in a quasi-waveguide interferometer with the thin film of the material was observed. The potential of the material for optical
switching was evaluated.
Received: 20 July 1998/Revised version: 11 September 1998 相似文献
9.
Two new ligands derived from phloroglucinol 2-{[(4-methoxy benzoyl ) oxy ] } methyl benzoic acid[L1] and 2-{[(4-methyl benzoyl
)oxy] methyl} benzoic acid[L2] were synthesized. The solid complex Eu(III)-L2 has been synthesised and characterized by elemental
analysis ,UV and IR spectra. The reaction of Eu(III) with the two synthesized ligands has been investigated in I = 0.1 mol dm-3 p-toluene sulfonate by cyclic voltammetry and square wave voltammetry. The reaction of Eu (III)–L1 and Eu (III)–L2 binary
complexes with nucleotide 5′-AMP , 5′-ADP ,5′-ATP , 5′- GMP , 5′-IMP , and 5′-CMP has been investigated using UV, fluorescence
and electrochemical methods. The experimental conditions were selected such that self-association of the nucleotides and their
complexes was negligibly small, that is, the monomeric complexes were studied. The interaction of the Eu(III)–L1 or L 2 solid
complexes with calf-thymus DNA has been investigated by fluorescence and electrochemical methods including cyclic voltammetery(CV)
,differential pulse polarography (DPP) and square wave voltammetry (SWV) on a glassy carbon electrode. The fluorescence intensity
of Eu(III)-L2 complex was enhanced with the addition of DNA. Under optimal conditions in phosphate buffer pH 7.0 at 25 °C
the linear range is 3–20 μM for calf thymus DNA (CT–DNA) and the corresponding determination limit is 1.8 μM. 相似文献
10.
Y. Zhang C. Y. Chen M. Huang Y. S. Wang Y. M. Zou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,56(2):157-166
Ab initio calculations of the total dielectronic
recombination (DR) rate coefficients for thirteen ions along the NiI
isoelectronic sequence in the ground state (Kr8+, Mo14+,
Ag19+, Sn22+, Xe26+, Nd32+, Gd36+,
Yb42+, W46+, Au51+, Pb54+, At57+, and
U64+) have been performed using the flexible atomic code. The
level-by-level calculations are performed for evaluating the DR
contributions through the relevant Cu-like autoionizing inner-shell
excited 3l174l′n′′l′′ and 3l175l′n′′l′′ configuration complexes with n′′
≤15, which are associated with Δn=1 and Δn=2
core-excitations, respectively. The usual (n′′)-3 scaling
law is found to be invalid for low-Z ions. A level-by-level
extrapolation procedure is employed to obtain the contributions
through higher n′′ complexes. The decays to autoionizing
levels followed possibly by radiative cascades could enlarge the
rates at relatively high temperature by a factor up to about 23%.
For the whole isoelectronic ions the contributions from
3s23p63d9 4l′n′′l′′ dominate the total DR
rates while the contributions from the 3s23p63d9 5l′n′′l′′ configuration complexes are about 10-20% at
relatively high temperature. On the basis of the calculated results,
a general analytic formula for the total DR rate coefficients of all
the ions with 36≤Z ≤92 along the NiI isoelectronic
sequence is constructed. The comparisons of the rates obtained from
the general formula with those from the detailed calculations show
that the formula is of high precision, generally better than 3%
accuracy for electron temperatures kT≥0.1EI, where EI is
the ionization energy of the Cu-like ion. The present DR rates at
temperature above 1.0EI are larger than the previously published
data by a factor above 30%. The commonly used semiempirical formula
proposed by Burgess and modified by Merts may overestimate the rates
at high temperature by a factor of about 2 for low-Z ions. 相似文献
11.
Jalilzadeh M Noroozi Pesyan N Rezaee F Rastgar S Hosseini Y Sahin E 《Molecular diversity》2011,15(3):721-731
Reaction of barbituric acid (BA), 1,3-dimethyl barbituric acid (DMBA) and 2-thiobarbituric acid (TBA) with cyanogen bromide
and various aldehydes in presence of triethylamine afforded a new class of heterocyclic stable 5-alkyl and/or 5-aryl-1H, 1′H-spiro[furo[2,3-d]pyrimidine-6,5′-pyrimidine]2,2′,4,4′,6′(3H,3′H,5H)-pentaones which are dimeric forms of barbiturate (uracil and thiouracil derivatives) at 0 °C to ambient temperatures. Structure
elucidation is proved by X-ray crystallography, 1H NMR, 13C NMR, FT-IR, CHN and mass analyses techniques. Mechanisms of the formations are discussed. 相似文献
12.
A.T. Hartlieb D. Markus W. Kreutner K. Kohse-Höinghaus 《Applied physics. B, Lasers and optics》1997,65(1):81-91
2 Σ+) was measured in a low-pressure H2/O2 flame for three rotational levels of OH (v′=1). Rate coefficients for collisions with H2O and N2 were determined. At 1600 K, kVET (N2) is (in 10-11 cm3s-1) 10.1±2, 6.1±1.8, and 3.8±1.3 for N′=0, 5, and 13, respectively. The kVET (H2O) is <1.1±1.8. The kQ (N2) is <2.4±8 for both vibrational levels. The kQ (H2O) in v′=1 is 59.1±6.5, 54.7±6.4, and 54.9±6.6 for N′=0, 5, and 13, respectively, and, determined indirectly, 74.6±10.4, 70.6±10.3, and 63.4±7.3 for N′=0, 5, and 13 in v′=0. A multi-level model of OH population dynamics, which is being developed for the quantitative simulation of experimental
LIF spectra, was extended to include VET. It was attempted to simulate state-to-state-specific VET coefficients for N2 collisions. From these simulations it appears that angular momentum conservation does not determine the N dependence of the
vibrational relaxation step.
Received: 9 September 1996/Revised version: 6 January 1997 相似文献
13.
M. Czerwiec R. Zachariasz J. Ilczuk 《The European physical journal. Special topics》2008,154(1):39-43
The mechanical and electrical properties in lanthanum
modified lead zirconate-titanate ceramics of 5/50/50 and 10/50/50 were
studied by mechanical loss Q - 1, Young's modulus E, electric
permittivity ε and tangent of dielectric loss of angle
tgδ measurements. The internal friction Q - 1 and Young modulus E measured from 290 K to
600 K shows that Curie temperature TC is located at 574 K and 435 K
(1st cycle of heating) respectively for ceramic samples 5/50/50 and
10/50/50. The movement of TC in second cycle of heating to lower
temperature (561 K for 5/50/50 and 420 K for 10/50/50) has been observed.
Together with Q - 1 and E measurements, temperature dependences of
ε=f(T) and tgδ=f(T) were determinated in temperature
range from 300 K to 730 K. The values of TC obtained during
ε and tgδ measurements were respectively: 560 K for
5/50/50 and 419 K for 10/50/50. These temperatures are almost as high as the
temperatures obtained by internal friction Q - 1 measurements in second
cycle of heating. In ceramic sample 10/50/50 the additional maximum on
internal friction Q - 1 curve at the temperature 316 K was observed. 相似文献
14.
A. S. Komolov N. B. Gerasimova E. F. Lazneva A. A. Gusarov A. Yu. Osadchev V. V. Shamanin 《Technical Physics》2009,54(2):301-304
The electrophysical parameters of polyhomoconjugated organosilicon polymer films are studied, and variation of their conductivity
under the action of water, toluene, and ammonia vapors is measured. Films 1–2 μm thick are prepared by the casting method
from a solution of poly[2,2-dimethyl-2-sila-1,3-propylene-(4, 4′-biphenylene)]a (polymer I) and poly[2-n -butyl-2-phenyl-2-sila-1,3-propylene-(4, 4′-biphenylene)]a (polymer II). In the course of conductivity measurement, organic
volatiles and water are adsorbed due to a stepwise rise in the pressure over the sample from 10−3 to 10−1 Torr. The initial values of the resistivity of polymers I and II are estimated as 4 × 109 Θ cm. Exposure of the films to organic volatile vapors and water vapor causes a reversible change in the conductivity of
the films. For polymer-I films, the conductivity upon adsorption of ammonia, toluene, and water vapors exceeds the initial
value by 150, 10, and 600 times, respectively. The sensitivity of polymer-II films is lower by a factor of 1.5–2.0. The time
of conductivity variation as the vapors are injected and evacuated is within 10 and 30 s, respectively. The mechanisms of
organic volatile and water adsorption on the surface of polyhomoconjugated organosilicon polymer films are compared with adsorption
mechanisms on the surface of π-polyconjugated organic films. 相似文献
15.
Shilpa M Nagababu P Kumar YP Latha JN Reddy MR Karthikeyan KS Gabra NM Satyanarayana S 《Journal of fluorescence》2011,21(3):1155-1164
Three symmetric ligands 7-methyl dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-CH3), 7-nitro dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-NO2) and benzo[i]dipyrido-[3,2-a;2′,3′-c]phenazine (dppn) and their ruthenium(II) complexes [Ru(en)2(L)][ClO4]2 (en= ethylenediamine), L= dppz-CH3, dppz-NO2 and dppn have been synthesized and characterized by IR, 1H, 13C NMR and Mass spectra. The interactions of these complexes with calf thymus DNA have been investigated by spectrophotometric,
spectrofluorimetric, circular dichroism, viscosity and thermal denaturation studies. As the planar extension of the intercalative
ligand increases, the interaction of the complex with DNA increases, indicating that the size and shape of the intercalalative
ligand has a marked effect on the strength of interaction. The plot of log K versus log [Na+] yield a slope of -1.26, -1.53, -1.60 for the complexes 1, 2 and 3 respectively. These three complexes have been found to
promote the cleavage of plasmid pBR 322 DNA upon irradiation. 相似文献
16.
J.R. Liu M. Itoh T. Horikawa E. Taguchi H. Mori K. Machida 《Applied Physics A: Materials Science & Processing》2006,82(3):509-513
The electromagnetic wave absorption properties of resin compacts containing 40 vol. % composite powders of α-Fe/C(a), and
Fe3C/C(a) were characterized in a frequency range of 0.05–26.5 GHz, according to a conventional reflection/transmission technique.
The real part (εr
′) and the imaginary part (εr
′′) of relative permittivity were constantly low in the 2–14 GHz (εr
′= ∼12.4 and εr
′′= ∼0.6) for α-Fe/C(a) resin composites, and in the 1–26.5 GHz (εr
′= ∼9.6 and εr
′′= ∼0.8) for Fe3C/C(a) ones. The imaginary part (μr
′′) of relative permeability exhibited wide peaks in the 1–9 GHz range for α-Fe/C(a), and in the 2–26.5 GHz range for Fe3C/C(a) owing to their different magnetocrystalline anisotropy field values. Consequently, the resin compacts with 40 vol. %
α-Fe/C(a), and Fe3C/C(a) powders provided good electromagnetic wave absorption performances (reflection loss <-20 dB) in ranges of 4.3–8.2 GHz,
and 9–26.5 GHz over absorber thicknesses of 1.8–3.3 mm, and 1.0–2.4 mm, respectively.
PACS 76.50.+g; 61.46.+w; 75.50.Bb; 75.30.Gw; 75.20.En 相似文献
17.
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
18.
Z.-Y. Jiao X.-Y. Kuang X.-F. Huang J.-H. Li M.-L. Duan 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(3):297-300
The complete energy matrices
for a d5configuration ion in a tetragonal
ligand-field has been constructed on the basis of the complete set of
basis
of d5configuration (252
dimension), and the relationship between the low-symmetry EPR parameters
b2
0 ,b4
0 and the local distortion parameters has been
established based on the complete energy matrices. As an application, we
have studied the EPR parameters and the local lattice structure of Mn2+
ion doped in tetragonal K2ZnF4 system. The calculation indicated that the local lattice structure around a tetragonal Mn2+ ion center has an expansion distortion. Simultaneously, the local lattice structure parameters R1 =2.0727 ?, R2 =2.0801 ? at room temperature (295 K) and R1
′ = 2.0439 ?, R2
′ =2.05478 ? at low
temperature (4.2 K) are determined. 相似文献
19.
The luminescence properties of Re(I) complexes incorporating the dcbpy ligand (dcbpy = n,n′-dicarboxylic acid-2,2′-bipyridine; n = 3, 4) were investigated as well as their utility as Pb2+ sensors. An unusual binuclear complex of the 3,3′- species was isolated. The emission intensity and lifetime for all complexes
were found to be highly temperature-dependent, with quantum yields and lifetimes dramatically greater at 77 K than at room
temperature. The monomeric 3,3′-dcbpy Re(I) complex demonstrates nearly 1:1 binding with Pb2+. The effect of this lead binding on the emission intensity is great, but the low quantum yields allow only for detection
of the metal at the micromolar level. The binding of Pb2+ to the 4,4′-dcbpy complex is modeled and the interaction is demonstrated to involve two binding sites. 相似文献
20.
Shengyi Yang Xiulong Zhang Zhidong Lou Yanbing Hou 《Applied Physics A: Materials Science & Processing》2008,90(3):475-478
In this paper, electroluminescence from organic light-emitting diodes based on 2-(4′-biphenyl)-5-(4′′-tert-butylphenyl)-1,3,4-oxadiazole (PBD) and N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TPD) is reported. Based on the exciplex emission from the TPD/PBD interface under high electric fields, the influence
of the TPD/PBD interface on exciplex emission was investigated by increasing the number of TPD/PBD interfaces while keeping
both the total thickness of the TPD layer and the PBD layer constant in the multiple quantum-wells (MQW) device ITO/TPD/[PBD/TPD]n/PBD/Al (n is the well number that was varied from 0 to 3). Our experimental data shows that exciplex emission can be enhanced
by suitably increasing the well number of this kind of MQW-like device.
PACS 78.60.Fi; 78.55.Kz; 73.61.Ph 相似文献