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1.
The effect of temperature on the spectral luminescence characteristics of PbWO4:Tb3+ crystals with synchrotron and laser excitation is studied. If PbWO4:Tb3+ is excited by synchrotron radiation with λ = 88 nm at 300 K, a faint recombination luminescence of the impurity terbium is
observed against the matrix luminescence. When the temperature is reduced to 8 K, the luminescence intensity of PbWO4:Tb3+ increases by roughly an order of magnitude and the characteristic luminescence of the unactivated crystal is observed. Excitation
of PbWO4:Tb3+ by a nitrogen laser at 300 K leads to the appearance of emission from Tb3+ ions. At 90 K, a faint matrix luminescence is observed in addition to the activator emission. The formation of the luminescence
excitation spectra for wavelengths of 60–320 nm is analyzed and the nature of the emission bands is discussed. 相似文献
2.
A rapid, simple and sensitive spectrofluorimetric method for determination of trace amount of ofloxacin was developed. At
pH 5.1 the ofloxacin enhances the luminescence intensity of the Eu3+ ion in Eu3+- ofloxacin complex at λex = 365 nm. The produced luminescence intensity of Eu3+-ofloxacin complex was in proportional to the concentration of ofloxacin. The working range for the determination of ofloxacin
was 5.0 × 10-9–5.0 × 10-6 mol L-1 with lower detection limit (LOD) and quantitative detection limit (QDL) of 3 × 10-9 and 9 × 10-9 mol L-1, respectively. The enhancement mechanism of the luminescence intensity in the Eu3+-ofloxacin system has been also explained. The method revealed good selectivity for ofloxacin in the presence of coexisting
substances and used successfully for the assay of ofloxacin in pharmaceutical preparations and serum. A comparison with other
standard methods was also discussed. 相似文献
3.
Attia MS Mahmoud WH Ramsis MN Khalil LH Othman AM Hashem SG Mostafa MS 《Journal of fluorescence》2011,21(4):1739-1748
A simple and sensitive spectrofluorimetric method for determination of trace amount of doxycycline hydrochloride (DC) in pharmaceutical
tablets and serum samples was developed. In ammonia buffer solution of pH 8.9 the doxycycline hydrochloride can remarkably
enhance the luminescence intensity of the Sm3+ ion in Sm3+- DC complex at λex = 400 nm. The produced luminescence intensity of Sm3+- DC complex in DMSO is in proportion to the concentration of DC and used as optical sensor for its determination. The dynamic
range for the determination of DC is 1 × 10−8 – 5 × 10−6 mol L−1 and in case of quantum yield calculations is 7 × 10−9 – 5 × 10−6 mol L−1 with detection limit of 6.5 × 10−10 mol L−1. The enhancement mechanism of the luminescence intensity in the Sm3+- DC system has been also discussed. A comparison with other spectrofluorimetric methods for tetracycline derivatives in which
Eu3+ ion is used instead of Sm3+ ion is also studied. 相似文献
4.
This paper explores an ultra-sensitive luminescence method for the determination of Ketoprofen (KP) in pharmaceutical formulations.
The technique is indirect and exploits the luminescence enhancement of terbium (Tb3+) by complexation with KP (Tb3+–KP), which was monitored at respective excitation and emission wavelengths of λ
ex = 258 nm and λ
em = 549 nm. The effect of varying the Tb3+ concentration and using multiple solvents was examined to determine optimal experimental conditions. Maximum sensitization
was accomplished in the presence of methanol where the most favourable condition for the formation of the complex was recorded
at a level of 1.0 × 10−5 M of Tb3+. Under these optimum experimental conditions, linear calibration curve was obtained in the range of 2.8 × 10−7–3.1 × 10−6 M with a detection limit of 8.7 × 10−8 M. The technique was validated with ‘working’ reference standards and produced relative standard deviations < 2% indicating
that the reproducibility was highly acceptable. The proposed method was successfully applied to assays of KP in pharmaceutical
formulations with average recoveries of 92–98%. The results were found to be in good agreement with those obtained by HPLC.
The method is highly suited for general applications of this nature. 相似文献
5.
A sensitive time- resolved luminescence method for the determination of meloxicam (MX) in methanol and in aqueous solution
is described. The method is based on the luminescence sensitization of europium (Eu3+) by formation of ternary complex with MX in the presence of 1,10- phenanthroline as coligand, Tween-80 as surfactant and
gadolinium ion as a co-luminescence reagent. The signal for Eu- MX-1, 10- phenanthroline is monitored at λex = 360 nm and λem = 620 nm. Optimum conditions for the formation of the complex in aqueous system were 0.01 M TRIS buffer, pH 8.0, 1,10- phenanthroline
(6.0 × 10−6 M) , Gd3+ (7.0 × 10−6 M), Tween-80 (0.28%) and 1.75 mM of Eu3+ which allows the determination of 20–800 ppb of MX with limit of detection (LOD) of 7 ppb. The relative standard deviations
of the method range between 0.1 and 1.1% indicating excellent reproducibility of the method. The proposed method was successfully
applied for the assay of MX in pharmaceutical formulations, plasma and in urine samples. Average recoveries of 99.8 ± 1.1%,
100.2 ± 0.9% and 100.9 ± 1.1% were obtained for MX in tablet, plasma and urine sample respectively. 相似文献
6.
The efficiency of excited-state interaction between Tb3+ and the industrial product Cilostazol (CIL) has been studied in different solvents. High luminescence intensity peak at 545 nm
of terbium complex in acetonitrile was obtained. The photophysical properties of the green emissive Tb3+ complex have been elucidated, the terbium was used as optical sensor for the assessment of CIL in the pharmaceutical tablets
and body fluids at pH 3.1 and λex = 320 nm with a concentration range 1.0 × 10−9–1.0 × 10−6 mol L−1 of CIL, correlation coefficient of 0.998 and detection limit of 7.5 × 10−10 mol L−1. 相似文献
7.
Youssef AO 《Journal of fluorescence》2012,22(3):827-834
A new, simple, sensitive and selective spectrofluorimetric method for the determination of Hydrochlorothiazide was developed
in acetonitrile at pH 6.2. The Hydrochlorothiazide can remarkably enhance the luminescence intensity of the Tb3+ ion doped in sol–gel matrix at λex = 370 nm. The intensity of the emission band of Tb3+ ion doped in sol–gel matrix was increased due to the energy transfer from the triplet excited state of Hydrochlorothiazide
to (5D4) excited energy state of Tb3 ion. The enhancement of the emission band of Tb3+ ion doped in sol–gel matrix at (5D4→7 F5) 545 nm was directly proportion to the concentration of Hydrochlorothiazide with a dynamic ranges of 5.0 × 10−10—5.0 × 10−6 mol L−1 and detection limit of 2.2 × 10−11 mol L−1. 相似文献
8.
A new, simple and accurate spectrofluorimetric method for the determination of metoclopramide hydrochloride was developed.
The metoclopramide hydrochloride can remarkably enhance the luminescence intensity of the Tb3+ ion doped in PMMA matrix at λex = 360 nm in methanol at pH 6.9. The intensity of the emission band at 545 nm of Tb3+ ion doped in PMMA matrix is increased due to the energy transfer from metoclopramide hydrochloride to Tb3+ in the excited stated. The effect of different parameters, e.g., pH, temperature, Tb3+ concentration, foreign ions that control the fluorescence intensity of the produced ion associate was critically investigated.
The calibration curve of the emission intensity at 545 nm shows linear response of metoclopramide over a concentration range
of 5 × 10−5–5.0 × 10−8 M with detection limit of 8.7 × 10−10 M. The method was used successfully for the determination of metoclopramide in pharmaceutical preparations and human serum.
The average recovery of 99.48% with standard deviation of 0.32% and 96.98% with standard deviation of 0.4%, of pharmaceutical
preparations and human serum respectively, were obtained which compared will with the results obtained from standard LC method
of average recovery 99.04% and standard deviation of 0.6% and average recovery of 98.19% with standard deviation of 0.6% of
pharmaceutical preparations and human serum, respectively. 相似文献
9.
Europium(III) Concentration Effect on the Spectroscopic and Photoluminescent Properties of BaMoO4:Eu
Ieda L. V. Rosa Ana Paula A. Marques Marcos T. S. Tanaka Fabiana V. Motta José A. Varela Edson R. Leite Elson Longo 《Journal of fluorescence》2009,19(3):495-500
BaMoO4:Eu (BEMO) powders were synthesized by the polymeric precursor method (PPM), heat treated at 800 °C for 2 h in a heating rate
of 5 °C/min and characterized by powder X-ray diffraction patterns (XRD), Fourier Transform Infra-Red (FTIR) and Raman spectroscopy,
besides room temperature Photoluminescence (PL) measurements. The emission spectra of BEMO samples under excitation of 394 nm
present the characteristic Eu3+ transitions. The relative intensities of the Eu3+ emissions increase as the concentration of this ion increases from 0.01 to 0.075 mol, but the luminescence is drastically
quenched for the Ba0.855Eu0.145MoO4 sample. The one exponential decay curves of the Eu3+ 5D0→7F2 transition, λ
exc = 394 nm and λ
em = 614 nm, provided the decay times of around 0.54 ms for all samples. It was observed a broadening of the Bragg reflections
and Raman bands when the Eu+3 concentration increases as a consequence of a more disordered material. The presence of MoO3 and Eu2Mo2O7 as additional phases in the BEMO samples where observed when the Eu3+ concentration was 14.5 mol%. 相似文献
10.
In the context, a modified sol-gel technology was afford to the synthesis of rare earth composite ceramic phosphors MM′O3/CeO2 and MM′O3/CeO2: Pr3+ (M = Ca, Sr; M′ = Ti, Zr) with multicomponent hybrid precursors were composed. The micromorphology, particle size and photoluminescence
properties were studied with XRD, SEM and luminescent spectroscopy in detail. Both XRD and SEM indicated the particle sizes
were in the submicrometer range of 100 ∼ 300 nm. The photoluminescence for these ceramic phosphors were studied in details
with the different component of host (molecular ratio of Sr, Ca and Ti, Zr), presenting a broad spectral band in the visible
blue-violet region with the maximum excitation peak at 449 nm and a wide emission range with a maximum peak at 619 nm, which
was ascribed to be the characteristic transition of Pr3+ (1D2 → 3H4). These phosphors can be expected for visible light conversion (blue → red) materials. Especially it can be found that the
introduction of CeO2 can enhance the luminescence intensity of MM′O3 and MM′O3: Pr3+. 相似文献
11.
We have studied photoluminescence and thermoluminescence (PL and TL) in CaGa2Se4:Eu crystals in the temperature range 77–400 K. We have established that broadband photoluminescence with maximum at 571 nm
is due to intracenter transitions 4f6 5d–4f7 (8S7/2) of the Eu2+ ions. From the temperature dependence of the intensity (log I–103/T), we determined the activation energy (E
a = 0.04 eV) for thermal quenching of photoluminescence. From the thermoluminescence spectra, we determined the trap depths:
0.31, 0.44, 0.53, 0.59 eV. The lifetime of the excited state 4f6 5d of the Eu2+ ions in the CaGa2Se4 crystal found from the luminescence decay kinetics is 3.8 μsec.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 112–116, January–February, 2009. 相似文献
12.
Yata PK Shilpa M Nagababu P Reddy MR Kotha LR Gabra NM Satyanarayana S 《Journal of fluorescence》2012,22(3):835-847
The three Ru(II) complexes of [Ru(phen)2dppca]2+ (1) [Ru(bpy)2dppca]2+ (2) and [Ru(dmb)2dppca]2+ (3) (where phen = 1,10 phenanthroline, bpy = 2,2-bipyridine, dmb = 2 ,2-dimethyl 2′,2′-bipyridine and polypyridyl ligand
containing a single carboxylate functionality dppca ligand (dipyridophenazine-11-carboxylic acid) have been synthesized and
characterized. These complexes have been shown to act as promising calf thymus DNA intercalators and a new class of DNA light
switches, as evidenced by UV-visible and luminescence titrations with Co2+ and EDTA, steady-state emission quenching by [Fe(CN)6]4− and KI, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments. The results suggest
that 1, 2, and 3 complexes bind to CT-DNA through intercalation and follows the order 1 > 2 > 3. Under irradiation at 365 nm,
the three complexes have also been found to promote the photocleavage of plasmid pBR322 DNA. 相似文献
13.
This paper reports the synthesis of high upconversion luminescent Gd2O3: Er3+, Yb3+ nanophosphor through optimized combustion route using urea as a reducing agent. The paper also reports the first observation
of upconversion emission bands extending upto the UV region (335, 366 and 380 nm) in Er3+–Yb3+ co-doped phosphor materials. The fuel to oxidizer ratio has been varied to obtain the maximum upconversion luminescence.
Three high intensity bands are found at 408, 523–548 and 667 nm due to the 4G11/2 → 4I15/2, 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions, respectively, along with the other bands. Input excitation power dependence has been studied for different transitions,
and the saturation effect and decrease in the slope of different transitions at higher input pump power has been explained.
Heat treatments of the samples show change in crystallite phase/size and relative upconversion luminescence intensities of
blue, green and red bands. The color of the phosphor emission has shown to be tunable with change in the crystal structure
as well as on excitation laser power and Er3+–Yb3+ concentration. The property of color tunability of the phosphor material has been used to record the fingerprint in different
colors. Also, the future prospect of the nanocrystalline phosphor material as a sensor for temperature, using FIR method,
has been explored. 相似文献
14.
Hongfei Jiang Guilan Wang Wenzhu Zhang Xiaoyu Liu Zhiqiang Ye Dayong Jin Jingli Yuan Zhiguang Liu 《Journal of fluorescence》2010,20(1):321-328
Because highly luminescent lanthanide compounds are limited to Eu3+ and Tb3+ compounds with red (Eu, ~615 nm) and green (Tb, ~545 nm) emission colors, the development and application of time-resolved
luminescence bioassay technique using lanthanide-based multicolor luminescent biolabels have rarely been investigated. In
this work, a series of lanthanide complexes covalently bound silica nanoparticles with an excitation maximum wavelength at
335 nm and red, orange, yellow and green emission colors has been prepared by co-binding different molar ratios of luminescent
Eu3+–Tb3+ complexes with a ligand N,N,N1,N1-(4′-phenyl-2,2′:6′,2′′-terpyridine-6,6′′-diyl)bis(methylenenitrilo) tetrakis (acetic acid) inside the silica nanoparticles.
The nanoparticles characterized by transmission electron microscopy and luminescence spectroscopy methods were used for streptavidin
labeling, and time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) as well as time-resolved luminescence
imaging detection of an environmental pathogen, Giardia lamblia. The results demonstrated the utility of the new multicolor luminescent lanthanide nanoparticles for time-resolved luminescence
bioassays. 相似文献
15.
Condensation product (L) of salicylaldehyde and semicarbazide behaves as a fluorescent sensor for Cd2+ ion, in 1:1 DMSO:H2O, over Mn2+, Fe2+, Ni2+, Co2+, Cu2+, Pb2+ and Hg2+ ions. The emission peak of L at λmax = 520 nm, on excitation with 420 nm wavelength photons, showed an enhancement in intensity of ca 60-fold when interacted with Cd2+ ion. The intensity was however found to remain unaltered when interacted with metal ions—Mn2+, Fe2+, Ni2+, Co2+, Cu2+, Pb2+ and Hg2+. The intensity increases by approximately 20 fold on interaction with Zn2+ ion. The increase in the fluorescent peak can be explained on the basis of photo induced electron transfer (PET) mechanism.
A 1:1 complexation between Cd2+ and L with log β = 4.25 has been proved. 相似文献
16.
V. I. Korepanov V. M. Lisitsyn V. I. Oleshko E. F. Polisadova S. S. Vil’chinskaya 《Journal of Applied Spectroscopy》2006,73(3):382-387
We have studied the spectral and kinetic characteristics of pulsed cathodoluminescence of feldspars (albite, microcline, amazonite)
in the time range 10−8–10−2 sec and the temperature range 28–300 K. We have shown that the bands in the UV region of the spectrum (5.39, 4.35, and 3.75
eV) are due to intrinsic luminescence of the crystals. The ratio of the intensities of these bands characterizes the phase
composition of the mineral: in the luminescence spectra of microcline, for all temperatures the 4.35 eV band dominates; in
the pulsed cathodoluminescence spectra of albite, the bands at 3.75 eV (at 300 K) and 5.39 eV (at 28 K) dominate. The parameters
of the luminescence decay kinetics for the impurity ions Fe3+ and Mn2+ are more sensitive to local perturbations of the lattice structure than the position of the emission band maximum, and can
be an effective indicator of the origin of the mineral.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 339–343, May–June, 2006. 相似文献
17.
A sequential three-dimensional (3D) particle-in-cell simulation code PICPSI-3D with a user friendly graphical user interface
(GUI) has been developed and used to study the interaction of plasma with ultrahigh intensity laser radiation. A case study
of laser–plasma-based electron acceleration has been carried out to assess the performance of this code. Simulations have
been performed for a Gaussian laser beam of peak intensity 5 × 1019 W/cm2 propagating through an underdense plasma of uniform density 1 × 1019 cm − 3, and for a Gaussian laser beam of peak intensity 1.5 × 1019 W/cm2 propagating through an underdense plasma of uniform density 3.5 × 1019 cm − 3. The electron energy spectrum has been evaluated at different time-steps during the propagation of the laser beam. When the
plasma density is 1 × 1019 cm − 3, simulations show that the electron energy spectrum forms a monoenergetic peak at ~14 MeV, with an energy spread of ±7 MeV.
On the other hand, when the plasma density is 3.5 × 1019 cm − 3, simulations show that the electron energy spectrum forms a monoenergetic peak at ~23 MeV, with an energy spread of ±7.5 MeV. 相似文献
18.
19.
A novel, simple, sensitive and selective spectrofluorimetric method was developed for the determination of trace amounts of
chlorzoxazone and Ibuprofen in pharmaceutical tablets using optical sensor Eu-Tetracycline HCl doped in sol–gel matrix. The
chlorzoxazone or Ibuprofen can remarkably enhance the luminescence intensity of Eu-Tetracycline HCl complex doped in a sol–gel
matrix in dimethylformamide (DMF) at pH 9.7 and 6.3, respectively, λex = 400 nm. The enhancing of luminescence intensity peak of Eu-Tetracycline HCl complex at 617 nm is proportional to the concentration
of chlorzoxazone or Ibuprofen a result that suggested profitable application as a simple optical sensor for chlorzoxazone
or Ibuprofen assessment. The dynamic ranges found for the determination of chlorzoxazone and Ibuprofen concentration are 5 × 10−9–1 × 10−4 and 1 × 10−8–7 × 10−5 mol L−1, and the limit of detection (LOD) and quantitation limit of detection (LOQ) are 3.1 × 10−10 , 9.6 × 10−10 and 5.6 × 10−10, 1.7 × 10−9 mol L−1, respectively. 相似文献
20.
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