Intense Orange Research Articles

Luminescence Investigations of RE3+ (RE3+ = Dy3+, Eu3+, Tb3+) Activated Na21(SO4)7F6Cl Optoelectronic Nanophosphors Under Near UV Excitation for LED

Optical properties of novel nanocrystalline phosphor in the Cl–F system doped with rare earth ions prepared by wet chemical method are discussed in this paper. The as prepared Na21(SO4)7F6Cl:RE3+ (RE3+ = Dy3+, Eu3+, Tb3+) nanophosphors were characterized by XRD, SEM, TEM, FT-IR, UV–Vis spectroscopy and photoluminescence spectroscopy. The formation of round shaped nanocrystalline phosphor material is realized by TEM images. The nanocrystalline phosphor shows the characteristic vibration of (SO4)2− of host lattice. The intense blue (Dy3+), orange (Eu3+) and green (Tb3+) emission are effectively excited by near UV light. This shows the applicability of these halosulphate optoelectronic nanophosphors for a near UV excited light emitting diodes.

Mn-doped Zinc Sulphide nanocrystals for immunofluorescent labeling of epidermal growth factor receptors on cells and clinical tumor tissues

The field of molecular detection and targeted imaging has evolved considerably with the introduction of fluorescent semiconductor nanocrystals. Manganese-doped zinc sulphide nanocrystals (ZnS:Mn NCs), which are widely used in electroluminescent displays, have been explored for the first time for direct immunofluorescent (IF) labeling of clinical tumor tissues. ZnS:Mn NCs developed through a facile wet chemistry route were capped using amino acid cysteine, conjugated to streptavidin and thereafter coupled to biotinylated epidermal growth factor receptor (EGFR) antibody utilizing the streptavidin–biotin linkage. The overall conjugation yielded stable EGFR antibody conjugated ZnS:Mn NCs (EGFR ZnS:Mn NCs) with a hydrodynamic diameter of 65 ± 15 nm, and having an intense orange–red fluorescence emission at 598 nm. Specific labeling of EGF receptors on EGFR+ve A431 cells in a co-culture with EGFR−ve NIH3T3 cells was demonstrated using these nanoprobes. The primary antibody conjugated fluorescent NCs could also clearly delineate EGFR over-expressing cells on clinical tumor tissues processed by formalin fixation as well as cryopreservation with a specificity of 86% and accuracy of 88%, in comparison to immunohistochemistry. Tumor tissues labeled with EGFR ZnS:Mn NCs showed good fluorescence emission when imaged after storage even at 15 months. Thus, ZnS nanobioconjugates with dopant-dependent and stable fluorescence emission show promise as an efficient, target-specific fluorophore that would enable long term IF labeling of any antigen of interest on clinical tissues.

Investigations on luminescence performance of Er3+/Sm3+ ions activated in BaGdF5 nanocrystals

A series of Er3+, Sm3+ and Er3+/Sm3+ codoped BaGdF5 nanocrystalline phosphors have been successfully synthesised by hydrothermal synthesis. Uniformly distributed nanocrystals with a spherical morphology and particle size of 30–40 nm were observed. X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence and decay studies were employed to characterise the samples. Under the 382 nm radiation excitation, the BaGdF5:Er3+ samples exhibit the typical green emission band of the Er3+ ions. With increasing the Sm3+ doped concentration, the highly intense orange–red emission bands of the Sm3+ ions were attributed to the effective energy transfer from the Er3+ to the Sm3+ ions, which has been justified through the luminescence spectra and the fluorescence decay dynamics.

Optical studies of Sm3+ ions doped Zinc Alumino Bismuth Borate glasses

Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of samarium (Sm3+) ions were prepared by using melt quenching technique and characterized for their lasing potentialities in visible region by using the techniques such as optical absorption, emission and emission decay measurements. Radiative properties for various fluorescent levels of Sm3+ ions were estimated from absorption spectral information using Judd–Ofelt (JO) analysis. The emission spectra and con-focal photoluminescence images obtained by 410nm laser excitation demonstrates very distinct and intense orange–red emission for all the doped glasses. The suitable concentration of Sm3+ ions in these glasses to act as an efficient lasing material has been discussed by measuring the emission cross-section and branching ratios for the emission transitions. The quantum efficiencies were also been estimated from emission decay measurements recorded for the 4G5/2 level of Sm3+ ions. From the measured emission cross-sections, branching ratios, strong photoluminescence features and CIE chromaticity coordinates, it was found that 1mol% of Sm3+ ions doped ZnAlBiB glasses are most suitable for the development of visible orange–red lasers.

New orange–red phosphor Sr9Sc(PO4)7:Eu3+ for NUV-LEDs application

• A novel orange–red phosphor Sr 9 Sc(PO 4 ) 7 :Eu 3+ has been synthesized and investigated. • The phosphors can be effectively excited by near UV (394 nm) light. • The thermal quenching temperature of Sr 9 Sc(PO 4 ) 7 :Eu 3+ is above 200 °C. A series of Eu 3+ ions doped Sr 9 Sc(PO 4 ) 7 orange–red emitting phosphors have been prepared by solid-state reaction method. Photoluminescence properties under near-ultraviolet (NUV) light excitation of the samples have been carried out. The studies show that the samples can be effectively excited by NUV (394 nm) which matches to the output wavelengths of near UV chips and exhibits intense orange–red emissions. Eu 3+ concentration was found to be optimum at x = 0.4 and the thermal quenching temperature of Sr 9 Sc(PO 4 ) 7 :0.4Eu 3+ is above 200 °C. Thus, the intense orange red emitting phosphor could be a promising phosphor candidate in generating white light combined with the NUV chip.

GdPO4:Eu3+ nanoparticles with intense orange red emission suitable for solar spectrum conversion and their multifunctionality

Gadolinium orthophosphate nanoparticles doped with Eu3+ have been successfully synthesized by co-precipitation in alkaline environment. As synthesized hexagonal GdPO4:Eu3+ nanoparticles (~10nm) transform to monoclinic nanocrystals in 20–50nm size range and 100–200nm size range upon annealing at 800°C and 1000°C respectively. Monoclinic nanocrystals show intense orange emission around 593nm due to radiative transitions from 5D0 to 7F1 triplet Stark split levels of Eu3+ as the most prominent group with estimated splitting of 17.71 and 11.33meV between Stark levels. The excitation range covers 250–400nm with maximum absorption at 395nm due to f–f transitions of Eu3+. The nanoparticles can efficiently convert UV and violet photons, available in terrestrial solar spectra, to intense orange and red light that can be harnessed by Si solar cells for photovoltaic conversion. Further, Gd in the host makes the luminescent GdPO4:Eu3+ nanoparticles highly paramagnetic rendering multifunctionality.

Concentration dependent structural and spectroscopic properties of Sm3+/Yb3+ co-doped sodium tellurite glass

Tuning the optical and structural behaviors of tellurite glasses with controlled dopants is the key issue in solid state lasers and amplifiers. Sm3+/Yb3+ co-doped sodium tellurite glasses are prepared by the melt quenching technique and characterized using XRD, FTIR and DTA, optical absorption and luminescence techniques. The XRD spectra reveals the amorphous nature of glasses and the presence of functional groups such as Te–O bond in trigonal bipyramids (TeO4), Te–O bending vibration of the trigonal pyramids (TeO3) and non-hygroscopic nature of the glasses are confirmed from FTIR spectra. The DTA measurement shows the thermal stability lies in the range of 106–123. The UV–vis–NIR spectra exhibit eight absorption bands corresponding to the transition from ground level 6H5/2 to the various excited state of Sm3+ ions and the broad absorption band in the range of ~825–1100nm is ascribed to the large contribution of the absorption from 2F7/2→2F5/2 transition of Yb3+ ion. The experimental oscillator strengths calculated from the absorption spectra are used to evaluate three phenomenological Judd–Ofelt (J–O) intensity parameters Ωλ (λ=2, 4 and 6). Emission spectra consist of four bands 4G5/2→6H7/2 (moderate green) 4G5/2→6H5/2 (intense orange), 4G5/2→6H7/2 (moderate orange-yellow) and 4G5/2→6H11/2 (feeble red). The J–O parameters are employed to calculate radiative parameters such as transition probability (AR), branching ratio (BR), effective bandwidth (λeff) and stimulated emission cross-section σ(λp) of these emission transition of trivalent samarium ion. The optical band gap energy value (Eopt) and Urbach energy values (ΔE) are calculated and compared. The concentration dependent spectroscopic behavior of Sm3+-doped and Sm3+/Yb3+co-doped glasses is understood. Our systematic study may contribute towards the development of optical device fabrication.

Synthesis, structure and tunable red emissions of Ca(Al/Si)2N2(N1−xOx):Eu2+prepared by alloy-nitridation method

A series of phosphors, Eu-doped Ca(Al/Si)2N2(N1−xOx), derivatives of CaAlSiN3, were synthesized by alloy-nitridation method. We demonstrated that their emission peaks can be tuned from 650nm to 610nm by oxygen preferential substitutions of nitrogen located at one of two crystallographic sites. Two luminescent centers corresponding to two types of Eu2+-coordination modes, i.e. EuNI2NII3 and EuNI2NII2O, were identified and accounted for the emission band structures, emission band shifts with oxygen/nitrogen substitutions, and the dependence of peak position and integrated emission intensity on temperature. As a typical example, Ca(Al/Si)2N2(N0.80O0.20):0.02Eu showed intense orange–red emission peaking at 622nm and kept the feature of excellent chemical stabilities, which would have potential applications in fabricating the white light-emitting diode. The excellent luminescent properties of these materials, such as wavelength-tunable red emission and excellent chemical stabilities, make them practical for use in typical LED package.

Controlled fluorescent properties of Zn(ii) salen-type complex based on ligand design

The synthesis, crystal structures, fluorescent properties and chirality of Zn(II) coordination complexes with two kinds of salen-type Schiff based ligands are reported. One of them is a chiral molecule and exhibits an unusually intense orange–red visible fluorescent emission in the present of THF, while the other is silent in photoluminescent emission.

NEW PROMISING HIGH QUALITY, SHARKA RESISTANT APRICOT CULTIVARS FROM CEBAS-CSIC (MURCIA, SPAIN) BREEDING PROGRAM

A major varietal renewal process is currently underway in apricot in order to satisfy consumer and industry demands. Consumers like the beauty and aromatic flavour of high-quality apricots, those with an orange ground colour, intense red blush, orange and juicy flesh and high organoleptic qualities. Other criteria, such as size, resistance to manipulation and good conservation aptitude, are taken into account in particular by the apricot industry. However, at present sharka (PPV) resistance is an extremely important trait for a variety to be cultivated in most traditional apricot areas. An apricot breeding programme is being developed at CEBAS-CSIC (Murcia, Spain) since the early nineties. Five new cultivars with good level of sharka resistance have been registered and released in the last years: ‘Rojo Pasion’, ‘Murciana’, ‘Mirlo Blanco’, ‘Mirlo Anaranjado’ and ‘Mirlo Rojo’ which respond to a large extent to the cultivation and market needs. They have low-to-medium chilling requirements, and are self-compatible cultivars with a high level of productivity and an early period of maturity (from early May to early June). High organoleptic quality, attractiveness, resistance to manipulation, good postharvest behaviour, aptitude for canning and sharka resistance are among others the main characteristics of the new cultivars. These positive characteristics mean that the five new apricot cultivars can play an important role in the varietal renewal process in Spain and maybe in other countries.

Novel multiband luminescence of Y2Zr2O7:Eu3+, R3+ (R = Ce, Bi) orange–red phosphors via a sol–gel combustion approach

A novel class of orange-red phosphors Y2Zr2O7:Eu3+, R3+ (R=Ce, Bi) was successfully fabricated by a facile sol–gel combustion method. XRD, TG–DTA and SEM results show that the heat-treatment of the powders at 800oC is enough to obtain highly crystallized Y2Zr2O7 samples. Photoluminescence spectra of the Eu3+-doped nanoparticles illuminated the simultaneous occurrence of several intense orange–red band emissions corresponding to the f–f transitions 5D0–7FJ (J=1, 2, 3, 4 and 5) of Eu3+ under 395nm excitation. The photoluminescence spectra of Y2Zr2O7:Eu3+, R3+ (R=Ce,Bi) showed that the luminescence intensity of Y2Zr2O7:Eu3+ was greatly enhanced by Ce3+ and Bi3+ by 260% and 165%, respectively. The possible sensitization mechanisms of Ce3+ and Bi3+ on Eu3+ emission intensity have been investigated and discussed in detail. The high brightness confirmed the potential applications of the phosphors in display devices and light-emitting diodes.

The effect of charge compensation by means of Na + ions on the luminescence behavior of Sm 3+-doped CaAl 4O 7 phosphor

Results of structural and spectroscopic measurements of Sm 3+ doped calcium aluminates: Ca 1− x Sm x Al 4O 7 and Ca 1−2 x Sm x Na x Al 4O 7 ( x=0.0005, 0.002, 0.01, 0.02, 0.03, 0.05) obtained by the modified Pechini method are presented. All samples yield intense orange–red emission under violet excitation (404.5 nm). Narrow bands corresponding to characteristic f–f intraconfigurational transition of Sm 3+ in excitation and emission spectra were observed. The influences of the concentration of Sm 3+ as well as charge compensation by co-doping with Na + ions on the luminescent properties of the phosphor were investigated. Detailed analysis of the emission spectra of Sm 3+ doped and Sm 3+,Na + co-doped CaAl 4O 7 powders proved that activator ions substitute Ca 2+ in the host. Co-doping with Na + ions enhanced greatly the intensity of the luminescence. Concentration dependencies of the intensity of luminescence and its decay kinetics proved the emission quenching at higher dopant contents due to cross-relaxation processes between Sm 3+ ions. Fitting of the 4G 5/2 state fluorescence decay to the Inokuti–Hirayama model indicated dipole–dipole interaction as the dominant mechanism of the cross-relaxation processes.

Preference ranking of colour in raw and cooked shrimps

The reddish colour to shrimp, which has been associated with its high quality, is one of the major factors for its acceptability by consumers. The aim of this work was to analyse consumer preference regarding colour in raw and cooked shrimps. Farmed shrimps Litopenaeus vannamei (13.8 + 1.16 g) were fed with control or supplemented food (60 ppm of carotenoids). The shrimp samples were analysed in naked eye, confirmed by colorimetry and sorted in the following categories: dark grey (L * 27.99; h 168.16), grey (L * 32.58; h 124.60), and light grey (L * 36.2; h 119.35) for raw shrimps; and intense orange (L * 61.49; h 54.69), orange (L * 65.97; h 57.79) and light orange (L * 72.65; h 70.17) for cooked shrimps. A preference ranking test was performed with 35 judges invited to rank the samples in descending order of preference. Consumers prefer lighter raw shrimp (light grey and grey) and brightly orange cooked shrimps (orange and intense orange), which indicates that supplementing shrimp food for pigmentation should be followed by improving its acceptance by consumer. These results indicate a challenge for the shrimp industry, as the lightest raw shrimps are also not so brightly orange coloured after cooking.

Microstructural and photoluminescence properties of Co-doped ZnO films fabricated using a simple solution growth method

Nanocrystalline 2% cobalt doped ZnO films were successfully prepared using a simple chemical solution method on glass substrates and subsequently annealed in air at 300 and 500 °C. Structural, morphology, chemical composition and photoluminescence properties of the films were characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and Fourier transform infra-red spectroscopy (FTIR) and photoluminescence (PL) spectroscopy. X-ray diffraction studies of the annealed films reveal the formation of polycrystalline hexagonal wurtzite structure of ZnO crystals without any co-related secondary phases. SEM micrographs of the films show the formation of spherical nanoparticles. Photoluminescence of the films showed a weak UV and defect related visible emissions like blue, blue–green, yellow and relatively intense orange–red emissions and their mechanism was discussed in detail.

Influence of synthesis condition on product formation: hydrothermal auto-oxidated synthesis of five copper halides with ratio of Cu(I)/Cu(II) in 1:1, 2:1, 3:1, 4:1 and 1:0

The hydrothermal synthesis and structural characterization of five copper iodides derived from chelated ligands, 1, 10-phenanthroline (phen), ethylenediamine (en) and 1, 3-propanediamine, are reported. Except monovalent copper compound 1 ((phen)Cu 3I 3 1), other four compounds ([Cu(phen) 2I][CuI 2] 2, [Cu(phen) 2I][Cu 3I 4] 3, [Cu(en) 2][Cu 4(phen) 2I 6] 4 and [Cu(1, 3-propanediamine) 2][CuI 2] 2 5) are mixed-valent Cu(I)–Cu(II) compounds by partially auto-oxidated from Cu(I). Supramolecular frameworks of these compounds can be assembled by C/N–H⋯I hydrogen bonds, Cu(I)–Cu(I) interaction, weak Cu–I semicoordinate interaction, C–H⋯ π and π– π stacking interactions. It's noteworthy that we find hydrothermal synthesis under higher pH value, higher synthesis temperature and longer reaction time can obtain higher ratio of Cu(I)/Cu(II) copper iodides and organic ligand with lower steric hinderance is prone to coordinated with divalent copper to form cation unit. Finally, the fluorescent study shows 1 exhibits intense orange–red luminescence with long lifetime at 293 K and more intense emission and longer lifetime at 77 K. Moreover, the room temperature EPR spectra of above five compounds not only show the valence of copper but demonstrate the coordination environment of Cu(II) centre.

Crystal structure and luminescence properties of Sr xCa 1 − xAlSiN 3:Eu 2+ mixed nitride phosphors

This study was performed to characterize the crystal structure and luminescence properties of Eu 2+-doped Sr x Ca 1 − x AlSiN 3 (0.2 ≤ x ≤ 1) red phosphor. Structural refinement was carried out using the Rietveld method. The unit cell volumes were shown to expand linearly with increasing Sr content throughout the whole solid solution range. As an end member, SrAlSiN 3:Eu 2+ phosphor was synthesized under a high pressure of 190 MPa and high temperature of 2173 K. The phosphor crystallizes with an isotypic structure of CaAlSiN 3 in the orthorhombic space group Cmc2 1 with lattice parameters of a = 9.8087(1) Å, b = 5.75600(8) Å, c = 5.16614(7) Å, and unit cell volume = 291.674(7) Å 3. This unit cell volume was larger than that of CaAlSiN 3:Eu 2+ by 4%. The phosphor showed intense orange–red emission by 5d → 4f transition of Eu 2+ at around 610 nm. Through the whole range of solid solution, Eu 2+-doped Sr x Ca 1 − x AlSiN 3 red phosphors showed a broad excitation band ranging from UV to visible light, and temperature characteristics comparable to those of CaAlSiN 3:Eu 2+ at the Eu concentration of 0.8 mol%.

EFFECTS OF LIGHT AND TEMPERATURE ON COLOUR CHANGES IN RIPENING FRUIT OF ACTINIDIA MACROSPERMA

Unripe, green fruit of Actinidia macrosperma turn an intense orange during ripening on the vine or after harvest. The change in colour is due to degradation of chlorophyll and synthesis of carotenoids. Temperature and light can influence the rate of colour change during storage of the fruit. Fruit harvested green and then stored at room temperature (c. 20°C) quickly turned a bright orange colour, irrespective of light regime. Green fruit stored at 4°C did not turn orange but instead became white or pale yellow over a period of 10 weeks. If these fruit were then shifted to room temperature, they rapidly turned bright orange. Changes in fruit colour during storage appear to be affected more by temperature than by light. It is concluded that carotenoid biosynthesis is more strongly affected by temperature than is chlorophyll degradation.

Photodegradation of the herbicide EPTC and the safener dichlormid, alone and in combination

Photodegradation of the herbicide EPTC ( S-ethyl- N, N-dipropylthiocarbamate), and the safener dichlormid (2,2-dichloro- N, N-diallylacetamide) has been examined in methanol and in water solutions. Irradiation of EPTC and dichlormid with UV light at 254 nm caused rapid degradation in both media. Remarkable and gradual changes in color of EPTC irradiated solution was observed from clear to yellow then to intense orange. EPTC half-life of elimination in water was 14.0, and 18.5 min, and in methanol 37.2 and 32.2 min, when irradiated with and without dichlormid, respectively. There was significant difference between rate of EPTC degradation in water and methanol in the presence or in the absence of dichlormid. Negligible degradation of EPTC or dichlormid at >290 nm was observed. Photoproducts were separated and identified using GC or/and thin-layer chromatography then identified using mass spectrometry. It appeared that some products have high molecular weight that formed as a result of dimerization. This is possibly a result of the coupling of radicals that formed through EPTC degradation. The cleavage of C–S and C–N bonds accounted for the formation of these radicals. Gradual dealkylation of the acid chains of EPTC has also occurred. EPTC-sulfoxide, EPTC-sulfone, Propylamine and dipropylamine were detected as photoproducts of EPTC at 254 nm. Dichlormid pathways of degradation at 254 nm were characterized as dechlorination, dealkylation, and hydrolysis both in water and methanol. The findings showed that dichlormid did not significantly affect EPTC photodegradation either at 254 nm or at >290 nm. The biological/toxicological properties of the photoproducts need further study, particularly the dimer compounds.

Hard/soft interactions in early transition metal chemistry: synthesis, properties and structures of thioether and selenoether complexes of titanium(IV)

Reaction of TiCl4 with L–L [L–L = MeE(CH2)nEMe; E = S or Se, n = 2 or 3, PhE(CH2)2EPh or o-C6H4(EMe)2] in anhydrous n-hexane solution under an N2 atmosphere results in the rapid formation of [TiCl4(L–L)] as yellow, orange or red solids. Analogous bromo and iodo species, [TiX4(L–L)] [X = Br; L–L = MeE(CH2)nEMe or o-C6H4(EMe)2; X = I; L–L = MeSe(CH2)2SeMe or o-C6H4(SeMe)2], were obtained as intense orange or red coloured solids by treatment of TiX4 with L–L in CH2Cl2 solution. Crystallographic studies on [TiCl4{MeS(CH2)2SMe}], [TiCl4{MeS(CH2)3SMe}], [TiCl4{MeSe(CH2)3SeMe}] and [TiCl4{o-C6H4(SeMe)2}] reveal a distorted octahedral arrangement with the coordinated group 16 donor ligand adopting the DL form in the first three cases and the meso form in the fourth example. These studies also reveal a trans influence series of Cl > S ≈ Se on Ti(IV). Solution NMR studies show that the chloro-compounds undergo rapid pyramidal inversion at ambient temperature, while the bromo and iodo species also undergo rapid ligand dissociation/chelate ring-opening. At low temperature these processes are slowed significantly, such that in most of the chloro and bromo species it is possible to identify both the meso and DL invertomers, although ligand exchange is still rapid at 200 K for the iodo species. The potential of these compounds as sources of titanium sulfide or titanium selenide phases via controlled decomposition is also discussed briefly. Finally, the dinuclear species, [Cl3Ti{MeS(CH2)2SMe}]2(μ-O), formed by partial hydrolysis of [TiCl4{MeS(CH2)2SMe}], has also been identified crystallographically.

Chemical, Physical and Sensory Attributes of Formed and Frozen, Baked Sweetpotato

ABSTRACTJumbo‐size, baked sweetpotato roots of Southern Delight and Carolina Bunch (CB) cultivars were prepared as a formed, frozen product. Cultivar differences affected composition slightly. A baking regime of 204°C for 70–80 min resulted in β‐carotene of 48.5 mg/100g, 2.3% greater than that at 190°C for 75–90 min. Between cultivars Hunter color values were different (p < 0.05). Color was an intense orange. Minor color changes occurred during 6 mo storage at −17°C, but no trend developed. CB produced the more acceptable product with greater purchase potential. Baking and storage exhibited minimum sensory effects.