共查询到20条相似文献,搜索用时 300 毫秒
1.
Belfield KD Corredor CC Morales AR Dessources MA Hernandez FE 《Journal of fluorescence》2006,16(1):105-110
The synthesis, photophysical characterization, and determination of singlet oxygen quantum yields (ΦΔ) for a class of fluorene derivatives with potential application in two-photon photodynamic therapy (PDT) is reported. It
has been demonstrated that these compounds possess the ability to generate singlet oxygen (1O2) upon excitation. A photochemical method, using 1,3-diphenylisobenzofuran (DPBF) as 1O2 chemical quencher, was employed to determine the singlet oxygen quantum yields (ΦΔ) of the fluorene-based photosensitizers in ethanol. ΦΔ values ranged from 0.35 to 0.75. These derivatives may have potential application as two-photon photosensitizers when pumped
via two-photon excitation in the near-IR spectral region. 相似文献
2.
The photophysics and cyclic voltammetry of two novel phosphorescent thiones, 2,2-dimethyl-indan-1-one-3-thione (DMIKT) and 2,2-dimethyl-indan-1,3-dithione (DMIDT), and three known phosphorescent thiones, 4H-pyran-4-thione (PT), 4H-1-benzopyran-4-thione (BPT) and 2,2-dimethylindan-1-thione (DMIT), have been characterised and compared. The phosphorescence emission of DMIT, DMIKT and DMIDT extends from the red into the near-IR spectral region. The additional carbonyl or thione group of DMIKT and DMIDT causes a significant shift in the emission maxima to 680 nm compared to that of DMIT, at 637 nm, in perfluorinated hydrocarbons. In acetonitrile the emission maxima of DMIKT and DMIDT are at 696 and 706 nm, respectively, and the spectra show vibronic bands which extend out beyond 850 nm. There is a significant
reduction in triplet lifetime along this series (from 44 (±2) μs (DMIT) to 10 ((±0.8) μs (DMIKT) in perfluorinated solvents, and 8.6 (±0.5) (DMIT), 1.3 (±0.5) (DMIKT) and 0.35 (±0.07) μs (DMIDT) in acetonitrile), as well as a reduction in the rate constant for ground-state quenching of the triplet, (from 9.8 ((±0.9)
to 3.5 ((±0.6) and 1.3 ((±0.2) × 109 mol−1 dm3 s−1 for the same compounds). The addition of the C=O or C=S groups also causes a decrease in phosphorescence quantum yield with
the highest emission quantum yield obtained for DMIT (Φ
P = 0.149 (±0.015)). Electrochemical studies show that while PT and BPT exhibit irreversible redox behaviour, DMIT, DMIKT and DMIDT all show at least one reversible reduction wave attributed to a one-electron process centred on the C=S moiety. The suitability
of these lumophores for use in OLEDs is discussed. 相似文献
3.
Wen-Zhong Zhu Qiu-Yue Lin Mei Lu Rui-Ding Hu Xiao-Liang Zheng Jian-Ping Cheng Yun-Yun Wang 《Journal of fluorescence》2009,19(5):857-866
Three novel complexes [Nd(L)(NO3)(H2O)2]·NO3·2H2O (HL1 = N-pyrimidine norcantharidin acylamide acid, C12H13N3O4; HL2 = N-pyridine norcantharidin acylamide acid, C13H14N2O4; HL3 = N-phenyl norcantharidin acylamide acid, C14H15NO4) were synthesized. HL1, HL2 and HL3 are the ligand of complex(1), complex(2) and complex(3), respectively. Their structures were characterized by elemental analysis, conductivity measurement, infrared spectra and
thermogravimetric analysis. The DNA-binding properties of the complexes have been investigated by fluorescence spectroscopy
and viscosity measurements. The results suggest that the complexes can bind to DNA by partial intercalation. The liner Stern-Volmer
quenching constant Ksq values are 3.3(±0.21)(1), 1.7(±0.19)(2) and 0.9(±0.04)(3), respectively. Complex (1) and (2) have been found to cleave pBR322 plasmid DNA at physiological pH and temperature. The test of antiproliferation activity
indicates that complex(1) has strong antiproliferative ability against the SMMC7721 (IC50 = 131.7 ± 23.4 μmol·L−1) and A549 (IC50 = 128.4 ± 19.9 μmol·L−1) cell lines. The inhibition rates of complex(2) (IC50 = 86.3 ± 11.3 μmol·L−1) are much higher than that of NCTD (IC50 = 115.5 ± 9.5 μmol·L−1) and HL2 (111.0 ± 5.7 μmol·L−1) against SMMC7721 cell lines. 相似文献
4.
O. ?palek J. Hruby M. ?ensky V. Jirásek J. Kodymová 《Applied physics. B, Lasers and optics》2010,100(4):793-802
A centrifugal spray generator of singlet oxygen, O2(1Δg), for driving a chemical oxygen-iodine laser was developed and its operation was experimentally studied. Modeling of the
liquid separation from the gas flow showed that the separator designed could remove droplets larger than 0.5 μm from gas,
which is very important for the laser operation. This result was confirmed by experiments. Experimental studies proved that
O2(1Δg) could be produced with a high efficiency (chlorine utilization 0.68–0.87 and O2(1Δg) yield 0.35–0.7) even at very high generator pressures (25–70 kPa), which cannot be attained by other O2(1Δg) generators. 相似文献
5.
I. V. Glavanakov P. Grabmayr Yu. F. Krechetov A. N. Tabachenko 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(6):747-749
Experimental research on positive-pion photoproduction on the oxygen nucleus in the 16O(γ, π+p) reaction at high recoil momenta of the residual nuclear system was performed. The yield for the 16O(γ, π+p) reaction was analyzed using a model that takes Δ-isobar configurations in nuclei ground states into account, together with
the earlier-measured yield of the12C(γ, π+p) reaction. The estimated number of isobars per nucleon N
Δ = 0.012 ± 0.005 was obtained for the 12C nucleus, and 16O N
Δ = 0.018 ± 0.004 was obtained for the 16O nucleus. 相似文献
6.
New values of a number of kinetic constants of processes proceeding in oxygen-iodine laser media are presented. The total
probabilities of formation of I2(X, 15 ≤ v ≤ 24) and I2(X, 25 ≤ v ≤ 47) molecules in the course of quenching of I* atoms by I2(X) are found to be 0.9 and 0.1, respectively. The quantum yield of singlet oxygen in the reaction O(1
D) + N2O → N2 + O2(a
1Δ) is close to 100%. The quenching rate constants of I2(A’) by O2, H2O, CO2, I2, and Ar and of I(2
P
1/2) by O(3
P), O3, NO2, N2O4, and N2O are presented. 相似文献
7.
V. Jirásek J. Hruby O. ?palek M. ?ensky J. Kodymová 《Applied physics. B, Lasers and optics》2010,100(4):779-791
A spray type of singlet oxygen generator for driving the Chemical Oxygen-Iodine Laser was developed. Singlet oxygen, O2(1Δg), is generated by a fast reaction of chlorine with basic hydrogen peroxide solution in the form of a dense spray. A mathematical
model of this reaction system showed that O2(1Δg) can be generated in this system with a high yield (0.70–0.80), high utilization of chlorine (0.75–0.95), and effective utilization
of liquid (0.36–0.54) at very high generator pressures (35–75 kPa). Experimental studies of this reaction system without an
efficient separation of liquid proved an efficient O2(1Δg) production characterized by a rather high product of chlorine utilization and O2(1Δg) yield (0.4–0.9) at very high generator pressures (30–80 kPa). This pressure is much higher than the operation pressure used
in other generators, which should be beneficial for a pressure recovery system of the COIL. These results provided the basis
for designing a centrifugal spray generator with an efficient separation of liquid from the gas flow, which is the subject
of the following paper. 相似文献
8.
I. V. Fekeshgazi N. R. Kulish N. I. Malysh T. S. Sidenko V. M. Trukhan T. V. Golyakevich 《Journal of Applied Spectroscopy》2009,76(1):107-111
We studied the two-photon absorption coefficient (β) for cadmium diphosphide (CdP2) single crystals in the tetragonal modification vs. the polarization azimuth (φ) of the incident light for intensities close
to the optical breakdown (or optical damage) threshold for the crystal (11 MW/cm2). We have established that the value of βmax = 0.16 cm/MW is reached for φ = 0, i.e., for the ordinary wave. At the lasing frequency of a ruby laser, β⊥/β|| = 2.13, which suggests anisotropy of the two-photon absorption in the studied crystals. These dependences are needed for
design and fabrication of quantum electronics and nonlinear optics elements whose operation is based on the use of the two-photon
absorption effect for high radiation fluxes.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 117–121, January–February, 2009. 相似文献
9.
The values of the insulator gap Δ in one-dimensional systems of interacting bosons described by the Hubbard Hamiltonian are
calculated at low temperatures by the quantum world-line Monte Carlo algorithm. The dependence of Δ on the size of the system,
the temperature, and the parameters of the model is investigated. It is shown that a chain with N
a=50 sites is already sufficient to estimate the thermodynamic value of the critical quantity (t/U)c for which a transition from the insulator into the superfluid state occurs in a commensurate system. To within the computational
error, this value, (t/U)c=0.300±0.005, agrees with the value (t/U)c=0.304±0.002 obtained previously by the combined “exact diagonalization + renormalization-group analysis” method. The characteristic
Kosterlitz-Thouless behavior of the insulator gap is demonstrated near the critical region: Δ∼exp[−b(1−t/t
c)−1/2].
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 2, 92–96 (25 July 1996) 相似文献
10.
Cheikh?L? Jean-Jacques?Aaron Václav?Kozmík Ji?í?Svoboda Jean-Claude?Brochon Li?Na 《Journal of fluorescence》2010,20(5):1037-1047
The synthesis, electrochemical and optical properties of three fluorescent substituted thieno[3,2-b][1]benzothiophenes (TBT)
derivatives, including 3-methoxythieno[3,2-b][1]benzothiophene (3-MeO-TBT), 2,3-dimethylthieno[3,2-b][1]benzothiophene (2,3-diMe-TBT),
and 6-methoxythieno[3,2-b][1]benzothiophene-2-carboxylate (6-MeO-TBT-2-COOMe), were investigated. The oxidation potential
values varied between 1.40 and 1.20 V/SCE according to the electronic substituent effect, and electropolymerization attempts,
performed in 0.1 M LiClO4 acetonitrile solution, led to the formation of very thin films of poly(3-MeO-TBT) and poly(2,3-di-Me-TBT). Electronic absorption
spectra, fluorescence excitation and emission spectra, fluorescence quantum yields (ΦF) , lifetimes (τF), and other photophysical parameters of the three new TBT derivatives were measured in DMSO solutions at room temperature.
For the methyl-and methoxy-substituted TBT derivatives, the fluorescence emission peak were slightly red shifted relative
to that of unsubstituted TBT (Δλem = 1–12 nm) whereas, in the case of 6-MeO-TBT-2-COOMe, a rather strong red-shift (Δλem = 73 nm) was attributed to the existence of a “push-pull” electronic interaction of the MeO and COOMe groups. All ΦF values were rather high, varying between 0.11 and 0.35, according to the substituent effect. Fluorescence decays were mono-exponential
and τF values were very short, ranging between 0.11 and 0.30 ns for the substituted TBT derivatives until study. 相似文献
11.
E. Birckner U.-W. Grummt H. Rost A. Hartmann S. Pfeiffer H. Tillmann H.-H. Hörhold 《Journal of fluorescence》1998,8(1):73-80
The absorption and fluorescence of substituted distyrylbenzene (DSB) derivatives and segmented poly(phenylene vinylene) (PPV)
derivatives are characterized by long-wavelength absorption maxima and absorption coefficients of λa = 380–450 nm, ε = 20,000–60,000 M−1 cm1 and fluorescence maxima, quantum yields, and decay times of λr = 440–530 nm, Φf = 0.2–0.9, and Τ = 0.8–2.5 ns, respectively. Alkoxy substituents at the central phenylene ring of DSB groups increase the
bathochromic shift in the spectra in comparison to DSB, without a significant decrease in the high DSB fluorescence quantum
yield. Both phenyl and cyano substitutions at the vinylene bridge lead to a further bathochromic shift of the fluorescence
and a decrease in the quantum yield to ca. 0.4. The DSB derivatives and the related segmented PPV derivatives show nearly
the same absorption spectra, fluorescence spectra, and radiative rate constantsk
f= Φf/Τ, indicating the efficacy of the segmentation of the polymer chain. The radiative rate constants determined by the Φf and Τ values and by the Strickler/Berg formula are in reasonable agreement. This supports the possibility of interpreting
the properties of the polymers in terms of their DSB units. The decrease in the emission anisotropy can be ascribed to multistep
energy transfer processes between different oriented segments. 相似文献
12.
Kun Yin Hui Xu Gaoyu Zhong Gang Ni Wei Huang 《Applied Physics A: Materials Science & Processing》2009,95(2):595-600
A novel europium complex Eu(TTA)3(CPPO)2 (1) (TTA=thenoyltrifluoroacetone, CPPO=9-[4-(diphenyl-phosphinoyl)-phenyl]-9H-carbazole) based on the phosphine oxide ligand
with bipolar structure was used to fabricate double-layer devices. The strong hole injection and transport ability of 1 was proved. The luminance of 414 cd m−2 was achieved with the device configuration ITO/Eu(TTA)3(CPPO)2(40 nm)/BCP (30 nm)/Mg:Ag (BCP = 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline), which is favorable among double-layer
organic light emitting devices based on small molecular Eu3+ complexes. The maximum current efficiency of 2.44 cd A−1 and external quantum efficiency of 1.55% demonstrate the potential application of 1 as a promising candidate for high-efficiency, simple-structure and pure red-emitting devices. 相似文献
13.
The energy level structure of F
3
+
laser color centers in crystals of LiF is discussed. A high-power laser (λ
ex=920 nm) is used to excite luminescence from LiF crystals with F
3
+
centers via two-photon absorption, and the dependence of the polarization and intensity of this luminescence on the polarization
of the laser light is measured and calculated. It is shown that the two-photon transition involves the excitation of a previously
unknown state of the F
3
+
center—a spin singlet whose wave function has 1
A
1 symmetry.
Fiz. Tverd. Tela (St. Petersburg) 39, 1373–1379 (August 1996) 相似文献
14.
Four novel copper(II) complexes of the composition [CuLX] where L = 2,6-bis(benzimidazole-2yl)pyridine, X = dipyridophenazine
(L1), 1,10-phenanthroline (L2), hydroxyproline (L3) and 2,6-pyridine dicarboxylic acid (L4) were synthesized and characterized by using elemental analysis, FT-IR, UV–vis, ESI-MS, molar conductance and magnetic susceptibility
measurements. The complexes [CuLL1](NO3)2 [1], [CuLL2](NO3)2 [2], [CuLL3](NO3) [3] and [CuLL4] (NO3) [4] are stable at room temperature. In DMSO the complexes [1] and [2] are 1:2 electrolytes, [3] and [4] are 1:1 electrolytes. Based on elemental and spectral studies five coordinated geometry is assigned to all the four complexes.
The interaction of four copper ion complexes with calf thymus DNA were carried out by UV–vis titrations, fluorescence spectroscopy,
thermal melting and viscosity measurements .The binding constant (Kb) of the above four metal complexes were determined as 5.43 × 104 M,−1 2.56 × 104 M−1, 1.21 × 104 M−1 and 1.57 × 104 M−1 respectively. Quenching studies of the four complexes indicates that these complexes strongly bind to DNA, out of all complex
1 is binding more strongly. Viscosity measurements indicate the binding mode of complexes with CT DNA by intercalation through
groove. Thermal melting studies also support intercalative binding. The nuclease activity of the above metal complexes shows
that 1, 2 and 3 complexes cleave DNA through redox chemistry. 相似文献
15.
Ryosuke Nakahara Satomi Kashitani Kumi Hayakawa Yuuki Kitani Takako Yamaguchi Yoshikazu Fujita 《Journal of fluorescence》2009,19(5):769-775
A fluorophotometric method for the determination of hydrogen peroxide (H2O2) using fluorescin was developed. This method was based on the oxidative reaction of fluorescin, a colorless, non-fluorescent
lactoid fluorescein, by H2O2 to give highly fluorescein fluorescence emission. In the determination of H2O2, the calibration curve exhibited linearity over the H2O2 concentration range of 1.5–310 ng mL−1 at an emission wavelength of 525 nm with an excitation of 500 nm and with relative standard deviations (n = 6) of 2.51%, 2.48%, and 1.31% for 3.1 ng mL−1, 30.8 ng mL−1, and for 308 ng mL−1 of H2O2, respectively. The detection limit for H2O2 was 1.9 ng mL−1 six blank determinations was performed (ρ = 6). This proposed method was applied to detection of other reactive oxygen species and nitrogen species (ROS/RNS) such
as singlet oxygen (1O2), hydroxyl radical (•OH), peroxynitrite (ONOO−) etc., and it was possible to detect them with a high sensitivity. In addition, this proposed method was applied to the recovery
tests of H2O2 in calf serum, human saliva, rain water, and wheat noodles; the results were satisfactory. 相似文献
16.
M. V. Zagidullin N. A. Khvatov M. S. Malyshev 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(6):969-973
The results of our experimental study of the kinetics of formation of O2(1Σ) molecules in energy-exchange reactions O2(1Δ) + I(5
p,2
P
1/2) and O2(a,1Δ) + O2(a,1Δ) are presented. The ratio of rate constants was obtained for these reactions (4800 ± 300). Setting the rate constant of
the deactivation of O2(1Σ) molecules on CO2 molecules at 4.1 · 10–13 cm3/s, we evaluated the rate constants for these reactions at a temperature of approximately 330 K: (1.7 ± 0.2) · 10−13 and (3.6 ± 0.5) · 10−17 cm3/s, respectively. 相似文献
17.
M. V. Parkhats V. A. Galievsky A. S. Stashevsky T. V. Trukhacheva B. M. Dzhagarov 《Optics and Spectroscopy》2009,107(6):974-980
The effects of the solution pH and polyvinylpyrrolidone on the dynamics and efficiency of the formation of singlet oxygen
1O2 in buffer media (pH 6.3–8.5) photosensitized by chlorin e
6 are studied. It is demonstrated that the quantum yield of the 1O2 formation photosensitized by chlorin e
6 decreases with decreasing solution pH due to the aggregation of photosensitizer molecules. Polyvinylpyrrolidone facilitates
the disaggregation of chlorin e
6, thus increasing its photosensitizing ability. For a complex of chlorin e
6 with this polymer, the luminescence kinetics of singlet oxygen is inverted, which should be taken into account in the determination
of the lifetime of 1O2 in real biological systems. 相似文献
18.
Oxygen quenching of excited triplet and singlet states of gas-phase anthracene and its derivatives that have similar energies
of the lower triplet levels but widely different oxidation potentials (0.44 < Eox < 1.89 V) was studied. Quenching rate constants for singlet (kSO2) and triplet (kTO2) states in addition to the fraction of oxygen-quenched singlet and triplet states qS
1(T1O2 were determined from the decay rates, fluorescence intensities, and delayed fluorescence as functions of oxygen pressure.
It was found that kSO2 values vary from 2·104 (9,10-dicyanoanthracene) to 1.2·107 sec−1·torr−1 (anthracene, 9-methylanthracene, 2-aminoanthracene) and kSO2 values from 5·102 to 1·105 sec−1·torr−1. The kSO2 values for anthracene, 9-methylanthracene, and 2-aminoanthracene, which have fast rates of interconversion from S1 to T1, are close to the rate constants for gas-kinetic collisions and are independent of the oxidation potentials (Eox). The quenching rate constants kSO2 for the other anthracene derivatives and kTO2 for all studied compounds decrease with increasing free energy of electron transfer ΔGET, which indicates the important role of charge-transfer interactions in the oxygen quenching of singlet S1- and triplet T1 states.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 36–42, January–February, 2008. 相似文献
19.
We report a new measurement of the Kerr effect of
molecular oxygen at λ= 1064 nm. The experimental value
reported for the anisotropy of the index of refraction Δ
nul, (3.15±0.85)×10-25 m2 V-2 atm-1,
is in good agreement with the value of 3.4×10-25 m2
V-2 atm-1 obtained via an ab initio calculation.
We show that the dependence of the effect on the pressure is not
linear because of the presence of a collision-induced absorption
band around 1060 nm due to the transition from the X3 Σ-g
ground state to the 1Δg state. We also give the value of
the quadratic anisotropy Δnuq
(-1.03±0.68)×10-25 m2 V-2 atm-2. We
finally compare our ab initio theoretical and experimental
results with previous existing data. 相似文献
20.
The energy E of the system as a function of the gauge phase Φ is calculated by exact diagonalization in a two-dimensional Cu4O8 cluster and by the slave-boson method for large systems. It is shown that motion of carriers with charge 2e, i.e., Cooper pairs, is observed for certain values of the parameters in the Hamiltonian. This motion is identified from
the onset of a characteristic maximum of E(Φ) at Φ≈Φ0/2, where Φ0 is the flux quantum. The phase diagram is constructed and the range of values of the model parameters where the effect is
observed is determined.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 2, 78–82 (25 January 1996) 相似文献