最新刊期
卷 24 ， 期 2 ， 2003
- 摘要：A set of specified protein,the molecular chaperones,could bind with other proteins which are not in native state and could promote them to achieve their functional conformations.MRJ (Mouse Related J-protein) is a kind of newly discovered chaperones and is the homologue of humandnaJ.By using denatured luci ferase as a molecular model to study the protein refolding and renaturation processes,the authors incubated the denatured luciferase with three kinds of chaper ones:MRJ,Hsp60,Hsp70,and their different combinations,respectively.Then,the bioluminescence from luciferin-ATP-Mg system,which catalyzed by differe nt ly treated luciferase,was measured.The results showed that all these chaperone s,MRJ,Hsp60 and Hap70,could somewhat increase the luminescence from the systems.But only the combination of these three chaperones did have the most signifi cant and most stable effects.The authors also found the whole processes were ob viously ATP-dependent.From the experiment the author concluded that (1) As a molecular chaperone,MRJ could facilitate the refolding of denatured luciferase; (2) Luminescence assay was a sensitive,accurate and quick method for the chape rone studies.关键词：molecular chaperone;MRJ;pro tein refolding;luminescence assay93|98|0更新时间：2020-08-11
- 摘要：Emission efficiency of the laser and luminescence materials depends directly on the concentration of active centers. In order to obtain a high efficient material, one usually hopes to increase the concentration to as a high level as possible. However, the energy transfer between active ions at a high concentration level often causes fluorescence quenching. Therefore, the study of energy transfer processes including resonant and phonon-assisted processes is important in both theory and practice. The effect of mass difference between ions of the host crystals on the phonon assisted energy transfer rates of activeions in the crystals has been discussed in this paper. Besides that resulted from the change of phonon frequency, this effect can be expressed as a multiplication factor D2 for the single-phonon assisted energy transfer and D4 for the two-phonon assisted energy transfer. The expressions of factor D for the case when the crystal is composed by two kinds of ions,i.e.n ions with mass m and n ions with mass m is
where n=n+n and m=nm+nm. Generally, when the crystal composed by p kinds of ion,one have 
It is clear that one can use this equation to take into account the influence of the mass difference on the energy transfer rates. 关键词：mass difference between host ions;energy transfer;phonon-assisted process85|85|0更新时间：2020-08-11 - 摘要：The properties of the electron-ripplon system on the surface of liquid helium film in a magnetic field influence the properties of liquid helium very markedly. The problem of a 2D electron on the surface of a liquid helium film was formlated by Jackson and Platzaman as a surface polaron problem. The properties of electron-ripplon system on the surface of liquid helium film in a magnetic field have been of considerable interest. In recent years the ripplon problem in a magnetic field has been studied by many theoretical methods and the properties of the ripplonic polaron in a magnetic field are measured using experimental method by many investigators. An electron on the surface of a liquid-helium film in a uniform magnetic field is studied as a polaron problem by Kato and Tokuda by an extended variational scheme of the Lee-Low-Pines theory.Using the harmo nicos cillator algebra,Lin,Chen and Jin calculate the ground-state energy of the system of an electron coupled to a ripplon on the outer surface of the liquid-helium film under the influence of a magnetic field of arbitrary strength. By means of a variational scheme of the Pekar type,a system of strongly coupled ripplonic polarons on the outer surface of liquid-helium film under the influence of a mag netic field of arbitrary strength is studied by Chen and Jin.Cesar et al. determined the energy spectrum of the surface electrons on liquid helium films in the presence of a perpendicular applied magnetic field by different approaches within second order perturbation theory.We studied the properties of the surface magnetopolaron in polar crystals by using a linear com bination operator method. However,by means of a linear combination operator method,the research on the pr operties of the electron-ripplon system on the surface of liquid helium fimls in a magnetic field has not been studied so far. The properties of the surface electron weakly and strongly coupled with ripplon on films of liquid helium in amagnetic field are studied. The vibrational frequency and ground state energy of the surface electron-ripplon system on liquid-helium films in amagnetic field was derived by using a linear combination operator method. The results show that,for the strong coupling the vibrational frequency λ of the surface electron-ripplon system on liquid hel ium films in a magnetic field will increase with increasing electron-ripplon coupling constant α and magnetic field B,whereas the ground state energy E0 will increase with increasing electron-ripplon coupling constant α and with de creasing magnetic field B.关键词：liquid helium film;ripplon;vibrational frequency;ground state energy89|81|0更新时间：2020-08-11
- 摘要：Photonic crystal is a new field which combines optics and condensed matter physics. It is also a great important research field of applied physics in recent years.This is an artificial multi-dimension periodic structure in the two background media which possess different dielectric constants. It is so called beca use its structure and characteristics resemble that of solid crystal. Photonicb and gap (PBG) structure is a periodic modulation of dielectric and it can exhibit "forbidden" frequency regions where electromagnetic waves can not propagate along any directions in the crystal. This may bring about some peculiar physical phenomena, as well as wide applications in several scientific and technical areas. Some great a chievements made in this paperare listed as follows. (1) PBG structures with absolute band gaps are designed via the calculation of photonic band structures by plane-wave expansion method. A two-dimensional photonic crystal is periodic along two of its axes and homogeneous along the third. A typical specimen, consisting of a square lattice of dielectric columns is shown in Fig.1. For certain values of the column, spacing this crystal can have a photonic band gap in the x1-x2 plane. The rods forming photonic crystal are characterized by a dielectric constant εa=17,they are embedded in a background medium whose dielectric constant is εb=1.The rods are of circular cross-section with radius r and the lattice constant of the square lattice is a with a>2r. The main idea is to lift the band degeneracy at high symmetry points in the Bril louin zone of crystals by lowering the structure symmetry of crystal. (2) It also gives a complete deduction for the electromagnetic wave theory of photonic crystal of two dimensions and Bloch wave solution in stratified periodic dielectric, offers the academic foundation of the existence of stop band, and for an example of two dimensional photonic crystal of square lattice demonstrates that dielectric rods in air background can generate a common band gap, which is called absolute photonic band gap, for both orthogonal polarization E and H.As to two dimensional (2D) PBG structures, a novel method is applied to substantially improve absolute band gaps by quasi-independently adjusting the refractive indices for E-polarization and H-polarization modes. This is acco mplished b y fabricating 2D PBG structures from an isotropic materials and selecting the extraordinaryaxis of uniaxial crystal parallel to the extension direction of cylinders. Such a novel mechanism should open up a new scope to design 2D photonic band gaps.关键词：photonic crystal;square lattice;plane wave ex pansion method;photonic band structure101|114|0更新时间：2020-08-11
- 摘要：Recently there has been an increased effort to develop cubic (3C-) SiC owning to its high electron mobility and high-saturation driftvelocity for the fabrication of high-power and high-temperature electronic devices. In this paper, we re po rt on the growth and electrical properties of voids-free n-3C-SiC/p-Si heter ojun ctions grown by LPCVD. The substrates are 2-inch p-type Si (100) wafers with resistivity of 10～12Ω·cm. SiH4, C2H4, and Pd-cell purified H2 were used as precurso r gases with flow rates of 2, 3sccm, and 3000 sccm, respectively. The LPCVD method at 5.32×104Pa was employed to grow 3C-SiC epitaxial films. In order to prevent the formation of voids and obtain improved interface of 3C-SiC/Si, much at tention has been paid to the pretreatment and carbonization process of the subst rates. It was obtained that the SiC/Si interface is smooth and there is no obvious voids formed in the Si substrate surface. This result indicates that the out-diffusion of Si atoms from Si substrates was suppressed during the epitaxial gro wth of SiC at 1250℃. Hall-effect measurements were performed to investiga te the electrical properties of the grown films with about 1.5μm in thickness in the temperature range from 80 to 300K. The mobility was 408cm2/Vs with the carrier concentration was about 7.2×1017 cm-3 at room temperature. Hall mobility obeys the T-α law in temperature range from 300 to 130K, where the value of α is 1.2. The I-V, C-V, and the temperature dependence of I-V curves in 3C-SiC heterojunctions with indium (In) and aluminum (Al) electrical pads, respectively, were in vestigated. The heterojunctions diodes (HJDs) with 0.5～1mm2 in area were obt ain ed by cleaving n-3C-SiC/p-Si. It was shown that with the introduction of a th in SiGe buffer layer between 3C-SiC and Si substrate, the reverse breakdown voltage and the current rectification ratio defined at ±1V bias were improved from 40V to 70V and from 3×102 to 7×103, respectively, for the diodes with In electrod es. The highest reverse breakdown voltage of approximately 100V was obtained in the 3C-SiC/p-Si heterojunctions with Al electrodes at room temperature. At low current densities the dependence of the forward current on voltage is exponential with the ideality factor of n=1.95 for both Al and In heterojunction diodes. The C-V characteristics of the diodes were linear in the C-2-V co ordinates, which means that the obtained n-3C-SiC/p-Si heterojunctions were abrupt. A built-in voltage (Vbi) of 0.75V was obtained.关键词：3C-SiC/Si heterojunctions;scanning electron microscope(SEM);I-V;C-V94|219|1更新时间：2020-08-11
- 摘要：CdSe1-xSx nanocrystals were grown by annealing silica glass with supersaturate Cd,Se and S at 500～800℃ for 4h, respectively. The absorption and photolumines cence (PL) of the nanocrystals excited with light of different wavelength were measu red at room temperature. The PL spectra were discussed. In the sample annealed at 550℃, no absorption and emission were observed in the range of 300～800nm. This suggested that no CdSe1-xSx nanocrystals formed. The absorption of 1S3/2-1Se shifted toward to red with the rising of growth temperatures from 600～800℃ due to the weakening of quantum confinement with the increase of nanocrystal sizes. Mainly broadened peaks named H and L bands, H band corresponding to recombination at the band edge and L band corresponds to radiative recombination as sociated with deep traps, were observed in the grown at 600～650℃. As the growth temperature was raised higher, L bands disappeared gradually and only H bands were observed. This indicated that deep trap density decreased with the increase of growth temperature and the deep traps mainly were surface states. H bands shifted red with the increase of nanocrystal growth tempe ratures. This was due to quantum size effects because nanocrystal mean size increased with the increase of growth temperature. In the nanocrystals grown at 650 ～800℃, a series of obvious small peaks superposed on the broadened bands were also observed. The peak energy for nanocrystals grown at different temperatures was similar and only new peaks were observed in samples grown at lower temperatures. The superposed peaks could be divided into two groups. Within each group, the peaks distributed periodically withenergy separation of 120meV. There was 50me Venergy separation between the two groups. The energy separation was much hig her than that of LO phonon. Size-selective PL spectra of nanocrystals collected using excitation wavelength between 488～650nm indicated that the superposed peak energy did not change with the excited wavelength, only the relative intensity varied with the excitation wavelength.关键词：nanocrystals;PL spectrum;fine structure93|115|1更新时间：2020-08-11
- 摘要：The microcavity organic light emitting diode with glass/Ag/PVK/Alq3/Al struct ure wa s fabricated using a typical emitting material,tris(8-quinolinolato)aluminu m, which is different from the conventional microcavity structure of Glass/DBR/ITO/Organic layers/Al. Because there is penetrate depth of about 1～1.5 λ (resonant wavelength) in DBR, it is difficult to realize single mode emitting. In our stru cture we used a thin metal layer to replace DBR/ITO acting as reflector and anode. The metal layer has very small penetrate depth and be easy to realize single mode emitting. The variation of mode density in microcavity as well as spectral narrowing and intensity enhancement were realized. The pure three color emission is observed and the intensity enhancement at resonance wavelength are increased by factor of 2～2.5. And the spectral halfwidths are narrowed by a factor of 1/3 compared to that of non-cavity OLED(100nm).97|87|0更新时间：2020-08-11
- 摘要：The rapid increase of information technique requests the continuous increase of process speed and enlarged capacity for the communication devices, thus some traditional communication technologies and devices could not fulfill the demands of applications. Therefore, the research of low cost, large capacity and high speed devices for the current and future information processing and transmitting are imminent. During the process of the research, polar polymer electro-optic modulators have attracted many researchers because their particular properties such as large electro-optic coefficient, low dielectric constant, low cost, simple fabricating technologies and faster response. Many devices based on the polar polymer are applied in the areas of the optical communications and the optical inter connects of integrated circuits. Among them, electro-optic modulators are used not only to research the properties of the polymer materials, but also to achieve modulation array, in addition, electro-optic film modulators are important components in free space optical interconnection systems. Besides, the film modulator could decrease device size and be benefit to high speed package. In this paper, the electro-optic modulator utilizing a polar polymer film wa s reported. The polymer was epoxy-p-nitroaniline-cinnamy. After spin-coated onto the indium-tin oxide glass to form into optical quality films. The polymer was baked at 60℃ for 30min, and dried in a drier for 12h to remove residual solvent. Then the film was corona polar at 90℃ for 30min with 10kV poling volta ge and 5μA poling current. After the film was cooled down to room temperature, an electro-optic film was formed with thickness about 2μm. The polar polymer film was sandwiched between two indium-tin oxide electrodes and placed in a Fabry-Perot etalon. The Fabry-Perotcavity is utilized to convert the phase modulation to amplitude modulation by multiple reflection and interference properties as the direction of poling is paralleled to the propagating of probe laser beam. An electro-optic modulator measuring system was established based on Fabry-Perot cavity and polar polymer film. The principle and the characteristics of the sy s tem were analyzed in detail, the measurement and calculation of modulation depth were also talked about. The electric signals propagating on the indium-tin oxide coplanar waveguide electrodes were successfully detected by the polymer film modulator. The results show that the film has the linear electro-optic effect. The modulation depth of polar polymer film modulator reach 0.01% when the finess e of Fabry-Perot cavity is about 20 (for optical wavelength of 1.3 μm) and modulati ng electric field is 1V/μm. The results are promising for technical applications in high speed electro-optic modulator and its integration.关键词：electro-optic modulator;Fabry-Perot cavity;electro-optic film;polar polymer109|135|2更新时间：2020-08-11
- 摘要：A great number of rare earth (Tb3+,Eu3+) complexes with aromatic carboxylic acid, β-diketone and phen etc. organic ligands have been synthesized, and their excellent luminescence properties have been used as luminescence materials and probe in the chemical and biological molecular systems. Very recently, a 10 candela-class white LED composed of a multiple quantum well InGaN blue light-emitting diode (LED) and a YAG:Ce phosphor has been developed.The white light is obtained by the integration of the blue InGaN LED die and the YAG phosphor into a single package. Several approaches are available to manufacture white LEDs, the thinking at several companies is that a violet or near-UV LED plus RGB phosphors will be the best overall method to make a white LED. In order to prepare high efficiency phosphor-based LED for general lighting, it is necessary to find some suitabl e phosphors for this purpose. In the present paper, a novel blue emission com plex of rare earth ions Tb3+,Eu3+ with N-phenylanthranilic acid and 1,10-phenanthro line was synthesized and characterized by luminescence spectra, IR spectra, UV-v is absorption spectra, DTA-TG and element analysis. It was found that the complex is a typical ligand emitting complex, which possess a strong emission spectra with peak wavelength lying at 444nm, and a wide excitation spectra with two adjace nt peaks at wavelengths 337nm and 407nm.This means that the synthesized blue phosphor can be used for the assembler of a new kind of blue LED. Results from the IR, U V-vis absorption spectra,DTA-TG and element analysis show that the comple x contained a great of N-PA and a little of rare earth as well as phen, the rare earthions coordinated with carboxyl group, and the azyl of N-PA link with phen through the nitrogen atom by the formation of hydrogen bond, which composes a good channel for the energy and electrons transmitting between ligands. The co-existence of rare earth ions(Tb3+,Eu3+) will enhance the formation of this channel and then intensify the ligands’ blue emission.94|69|5更新时间：2020-08-11
- 摘要：That is a key factor to improve the efficiency for realizing the application of organic light-emitting diodes (OLEDs). The function layers were doped witheach other to form transition layer in order to balance the carriers injected. Meanwhile, the electrons and holes injected are effectively confined in the active layer, which leads to the increase of carriers encounter. Thus the EL efficiency was elevated. The device exhibited the maximum emission of 49300cd/m2 at the driving voltage of 35V. The maximum efficiency is 7.96cd/A at 10.5V, which was improved by twice in comparison with the conventional doped devices. Meanwhile, the device exhibited superior operational stability with a half-life time of 1000h at a constant current density of 26.7mA/cm2 with the starting luminance of 1000cd/m2.关键词：OLEDs;doping;efficiency;lifetime78|93|0更新时间：2020-08-11
- 摘要：High quality and high resistivity (0001) GaN film was grown on (0001) plane sapp hire by metalorganic vapor phase epitaxy (MOVPE). To measure the surface a coustic wave (SAW) properties accurately, metallized interdigital transducers (IDT) we re deposited on the GaN surface. The pitch of the IDT was 15μm (=λ/4,λ:S AW w avelength), and the number of IDT finger pairs was 40. The surface acoustic wave velocity on free surface and that on metal surface were measured by pulse metho d respectively, and then the electromechanical coupling coefficient was calculat ed. The surface acoustic wave velocity (v) and electromechanical coupling coefficient (κ2) were measured as 5667m/s and 1.9% respectively.关键词：GaN;surface acoustic wave velocity;electromechanical coupling coefficient107|188|1更新时间：2020-08-11
- 摘要：This paper deals with silicate long afterglow phosphors. It is reported in the first time that the afterglow time of the silicate phosphors can be last more than ten hours. Series of silicate long afterglow phosphors doped with Eu were made in M-M′O-SiO2(M=Ca,Sr,Ba; M′=Mg,Zn,Cd) system. It is found that disilicate of akermanite structure and silicate of okenite structure doped with Eu2+, Ln have the best afterglow properties. The excitation and emission spectra, afterglow characteristics of the above phosphors were measured and investigated. The luminescence comes from typical 5d→4f transfer of Eu2+. Emission color responds to M and structure, it changes continuously from blue to yellow. It is shown in decay curve that its afterglow property is better than the traditional (Ca, Sr) S:Bi blue long afterglow ph osphors. The best afterglow property comes from disilicate doped with Eu, whose afterglow time is more than ten times of (Ca,Sr)S:Bi, after illuminating stopped 60min. Thermoluminescence spectra identified the existence of long afterglow luminescence. It is known by the measurement of X-ray diffraction patterns that the luminescent material is akermanite crystal. It is shown by the result of anti-water experiment that the anti-water property of CaSr silicate phosphor doped with Eu2+ is obviously better than that of aluminates system long afterg low phosphors.关键词：long afterglow;silicate;akermanite;okenite185|132|16更新时间：2020-08-11
- 摘要：Among several methods to grow the ZnO film, the DC sputtering (DCS) by using sil icon or silicate substrate appears easier in growth and with lower cost. However, the later needs high temperature (800～1000℃) treatment in order to obtain the film with a qualified orientation. It is then the motivation in our research to study the annealing effect on the structure and the luminescent characterization of the ZnO films. In our previous work, the X-ray diffraction with glancing input angle (GXRD) was measured on as-grown and annealed samples, which indicated a triangular compound zinc silicate appeared while the temperature higher then 800℃. In this work, the cathodoluminescence (CL) spectra of a ZnO film on Si, a nnealed at different temperature, were measured. The results showed that, the crystal quality of the film improved with increasing the annealing temperature, while the hexagonal phase of the ZnO film transformed into a kind of mixture phase including a hexagonal and a trigonal phase, after annealing at the temperature lower then 800℃ for one hour. The CL spectrum also shows the intrinsic emission bands of ZnO (two emission bands at 390nm UV band and 505nm green band) and Zn2SiO4(just one emission band at 525nm), in which the ZnO is the main source of the spectrum (this is indicated by the red shift of the green band from 505nm to the 525nm band, and the width of the green band was narrowed, as increasing the annealing temperature). Increasing the temperature continuously up to 950℃ changed the main source of sample’s luminescence from the emission of ZnO to the emission of zinc silicate (the red shift stopped at the 525nm). This indicates acreation of new ternary compound Zn2SiO4 in the film. In conclusion, in order to obtain a qualified crystalline ZnO films on silicon or silicate glass grown by DCS method, it is necessary to use heat treatment with high temperature. Although the crystalinity of the film was improved along with increasing the annealing temperature, however, a new ternary compound Zn2SiO4 with triangular structure was found in the films annealed at the temperature higher than 770℃. Therefore, we have to face to such perplex if we decide to choose the DCS or other methods which needs a high temperature treatment to grow ZnO film on silicon, although such methods may have fairly simple techniques and are cheap in cost.关键词：ZnO;silicon substrate;high temperature annealing;cathodoluminescence;Zn2SiO493|88|6更新时间：2020-08-11
- 摘要：Luminescent materials based on Zn2SiO4:Mn are used as the green component of projection television and ppc copy machines due to its high luminesc ence efficiency. The sol-gel technology, characterized by simple procedures and facilities, is very suitable for deposition of thin amorphous and crystalline films, which have found applications in many fields. Future integrated circuits will require reliable technique for fabricating nanometer-scale devices. Optical lithography or photolithography, which has been and will be the mainstay of lithography for the near future, is expected to be limited to 100nm resolution. In this paper, Mn2+-doped Zn2SiO4 phosphor films and their patterning were fab ricated on silicon and quartz glass substrates by sol-gel process (dip-coating) combined with a soft lithography. The resulted film samples were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), optical microscope and photolumines cence excitation and emission spectra. The results of XRD reveal that these film sremain amorphous below 700℃, begin to crystallize at 800℃ and crystallize completely around 1000℃. The grain structure of the film can be seen clearly fro m AFM micrographs, where particles with average size of 220nm can be resolved. the films show a strong green emission with a maximum at 522nm and corresponding excitation band was ranging from 220 to 280nm with a maximum at 248nm. Four kinds of patterning structures with film line widths of 5, 10, 20 and 50μm have been obtained by micromolding in capillaries soft lithography technique. The optical microscopy micrographs show that the film bands had a 10%～20% shrinkage after firing.关键词：sol-gel process;luminescence;soft lithography;Zn2SiO4：Mn95|95|0更新时间：2020-08-11
- 摘要：Zirconia has attracted very much the attention of technologists and scientists due to its combined electrical, chemical, optical, and mechanical characteristics. Zirconia has prominent characteristics such as chemical stability, high mechan ical strength, high resistance to corrosion, heat resistance, electric insulation, high refractive index, etc, which makes this material suitable for optical application. It has been reported that pure zirconia presents low phonon energy, increasing the probability of radiative transitions in rare-earth doped samples. Interest in nanocrystalline zirconia ceramics with average grain sizes below 100 nm has increased during the past few years as their properties (such as sinterability and superplastic behavior) are often significantly different and considera bly improved compared with conventional zirconia ceramics with coarser grain structures. Synthesis of powder with high purity, ultrafine, agglomerate-free and narrow size distribution is the first and perhaps the most important step in producing nano-zirconia ceramics with desirable microstructure and characterization. Various techniques including wet-chemical synthesis by precipitation of hydroxides from salt have been the most commonly used methods for the synthesis of nano-zirconia powders. In this paper, Zirconia doped with 1% Er3+ ions was prepa red by solid phase reaction method. The XRD showed that the crystal structure of this material was polygonal. Raman spectrum indicated that its phonon energy waslow. Its emission spectrum under the excitation of the third harmonic of a Nd:YAG laser (355nm) and its up-conversion spectrum with strong green emission and weak red emission under the excitation of a semiconductor diode laser (980nm) we re obtained. The strong green and weak red emission was caused by the low phonon energy and the low doped concentration in the sample.关键词：zirconia;Er3+;luminescence;phonon energy93|73|1更新时间：2020-08-11
- 摘要：The phosphors of Sr4Al14O25:RE3+ (RE=Eu, Ce, Tb) were sy nthesized by high-temperature solid state reaction.The doping ions all occupy two different sites in the matrix. The two charge transfer bands and two 5D0→7F0 emission lines in the spectra shows that Eu3+ ions occupy two latticlsites in Sr4Al14O25:Eu3+.In the excitation spectrum of Sr4Al14O25:Ce3+, there are two broad bands at 265 and 335nm resp ectively, due to the transitions from the ground states of 2F5/2 and 2F7/2 to the excited state of 5d.Because of the large overlap between the emission bands, we couldn’t separate them from each other, even reducing the slit width.We could get two bands at 362 and 385nm with the Gaussian-fitted method by origin soft. The energy difference between them is 1650cm-1, lower than that of 2F5/2 and 2F7/2, viz. 2000cm-1 as usual.The intensity of 385nm band relative to that of 362nm in the case of 335nm excitation is stronger than that in the case of 265nm excitation, which might be due to the energy transfer from the 362nm band to the 385nm band.Similar phenomenon appeared in the phosphor of Sr4Al14O25:Eu2+.In Sr4Al14O25:Tb3+, the emission spectra are different from each other in the cases of the excitations at 235 and 241nm.At the excitation of 235nm, the 382nm band is the strongest emission peak, while at the excitation of 241nm, the 545nm one instead of it.The above analyses confirmed that these three ions all had two light centers, just like Eu2+ ions in this host.The emissions from the levels of 5D3 and 5D4 of Tb3+ appear at the same time, which shows that the non-radiative process between them is inefficient.In the excitation spectrum of the Tb3+ emission of Sr4Al14O25:Ce3+, Tb3+ sample, there are not only the absorption of Tb3+, but also the absorption of Ce3+, which shows that Ce3+ could sensitize Tb3+. And the energy transfer from Ce3+ to Tb3+ is not complete because the emission spectrum consists of both Ce3+ and Tb3+ emissions.91|50|0更新时间：2020-08-11
- 摘要：The samples in Ba0.04Mg0.16Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9)and Ba0.1Mg0.1Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9) were synthesized by solid-state reaction. According to X-ray diffractions,the structure of the samples were single-phase and formed solids. The excitation spectra of Ba0.04Mg0.16Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9) and Ba0.1Mg0.1Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9) were located at the scope of 100～300nm,and composed of tw o continuous zones:the first one originated from the host absorption about 170nm,the second one originated from the absorption of the transition 3d5→3d44s1 of Mn2+ around 190～200nm.The absorption more than 200nm was very weak.It is said th at the absorption of VUV was very strong,and the absorption of UV was weak in the system of Ba0.04Mg0.16Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9)and Ba0.1Mg0.1Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9). The host absorption was very strong,the emission was almost invisibility,and the Mn2+ emission was very strong that the energy transfer from the host to Mn2+ can be observed.In the system of Ba0.04Mg0.16Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9), when the n increased from 4.1 to 4.9 that the emission sp ectra were changed obviously.At first,the peak was moved to red as the n=4.1～4.5. The peak moved to 178nm when then equaled 4.5. The peak was at 170nm as n=4.6～4.9.In the system of Ba0.1Mg0.1Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9), Al3+ was taken the place of Mn2+, and come in to the center of tetrahedron in lattice.Of course,the brightness was reduce das then was increased.When the value of n and content of Mn2+ were changed in a scope, a high efficiency green luminescent material of Ba0.04Mg0.16Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9)and Ba0.1Mg0.1Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9) would be obtained. The luminescent material in the system of Ba0.04Mg0.16Sr0.8O·nAl2O3:Mn0.072+ and BaMg0.1Sr0.8O·nAl2O3:Mn0.072+ (n=4.1,4.2...4.9) will be used in PDPs in the future.关键词：PDP;aluminate;luminescence76|105|1更新时间：2020-08-11
- 摘要：The electroluminescent phosphors are the important materials of new type cabin signal display EL screen used for displaying the data of the main battle aircraft. The electroluminescent phosphors are the third-generation illumination system which is designed to complete instrument data for the traditional one. The new screen can change electrical energy directly into optical energy and works without external luminous source, it is the successful solution to many problems lying in the fluorescent display and the bead lamp display. Electroluminescence is based on the semiconductor material such as ZnS doped with Cu and Mn drove by electric field. As a kind of solid cold light source, EL has gained wide application in the luminaire and display fields. We apply successfully the EL display panel in a series aircraft cabin signal display screen.关键词：electroluminescence;phosphors;display screen89|82|0更新时间：2020-08-11
- 摘要：Molecular aggregates have the potential applications on nonlinear optics and integrated optics. Unique properties of one dimension nanostructure dye molecular J-aggregates are different from either monomers or bulk materials. The unique optical properties of molecular aggregates, not observed in crystals are superradiant emission and giant optical nonlinearities. Superradiance is caused by the fact that the oscillator strengths of the coupled molecules are swept together in a few eigenstates, which thus obtain agiant transition dipole to the ground state and are therefore superadiant: their radiative decay rate enhanced linearly with the number of coupled molecules N. Absorption of aggregates and superradiance are resonant in the spectra. The nonlinear refractive index, absorption coefficiency and polarizibility were measured with Z-scan.It is observed that three order nonlinear polarizibility was increased with chain lengths shortening and the mechanism was analyzed and discussed.关键词：J-aggregate;superadiation;Z-scan89|121|0更新时间：2020-08-11
- 摘要：At present, porous silicon(PS) can be prepared by different methods.Porous silicon fabricated by anodic etching, photochemical etching and chemical etching were reported respectively,but the difference of the three methods has not yet been reported. The substrates used in this work were all n-type Si wafer with resistiv ity between 4～7Ω·cm and (100) crystalline orientation.The first sample was prepared by anodic etching method in double-cell which made of teflon.The anodic etching was carried out in a solution of HF:ethanol=1:1 at constant current density of 3mA/cm2 at room temperature.The second sample was prepared by photochemical etching method using a 632.8nm line from a He-Ne laser of 1.5mW in the solution of the same as the first. The third sample was prepared by chemical etching method in a solution of V (HF): V (HNO3): V (H2O)=1:1:1.5 without current or light assistant. Formation mech anism of PS was analyzed and photoluminescence(PL) spectra of the three samples was investigated in this paper. Anodic oxidation method is the best one verified by comparing experimental setup,preparing conditions,formation mechanism and photoluminescence spectra.In addtion,free carriers play an important role in the formation process of porouss ilicon.105|99|1更新时间：2020-08-11
- 摘要：Organic film photovoltaic cell, ITO/TPD/Gd(DBM)3bath/Mg:Ag, was fabricated. The TPD, N,N’-diphenyl-N,N’bis(3-methylphenyl)-1,1’-diphenyl-4,4’-diamine, and Gd(DBM)3bath, gadolinium (dibenzoylmethanato)3(bathophenanthroline), are the electron acceptor and donor, respectively. Fabrication process is indicated shortly. Although TPD acts as an active layer in the bilayered cells, insertion of a Gd-complex film between TPD and the alloy cathode is necessary for efficient carrier photogeneration. Under the irradiation of 365nm UV light with 4mW/cm2, the cell shows short-circuit current of 29.24μA/cm2, open-circuit voltage of 3.2V, fill factor of 0.286 and external quantum efficiency of 2.73, respectively. And the spectral response region of EQE is matched to the absorption spectrum of TPD film, suggestingt hat it’s the absorption of TPD layer but not that of the Gd(DBM)3 bath plays a dominant role in the creation of photovoltaic. We also demonstrated the rela tions hip between photovoltaic phenomena and exciplex, [TPD+...Gd(DBM)3bath-]*, which generated at the interface between TPD and Gd(DBM)3 bath layers. And we can say that in the photovoltaic progress the exciplex [TPD+...Gd(DBM)3bath-]* acts as a hole-electron pair, or in other words, acts as light-generated exciton.关键词：organic film photovoltaic cell;exciplex;external quantum efficiency;open-circuit voltage;short-circuit current99|102|0更新时间：2020-08-11
- 摘要：Multi-sheet InGaN quantum dots grown by a new method is reported, which is much different from the present quantum dots growth method. The dots are formed by de creasing the growth temperature and increasing the adatom-hopping-energy barrier through surface passivation. Thus the new method can be called as a passivation-low-temperature (PLT) method. Atomic force microscopy measurement reveal that the monolayer InGandots were small enough to expect zero-dimensional quantum effects. The size of monolayer QDs is typically 40nm wide and 15nm high. The QDs on upper layer can be grown bigger. The photoluminescence of (0001) InGaN multi-sheet QDs is measured. The PL spectra of (0001) InGaN/GaN multiple layers QDs show not only the QDs-related peak but also an additional peak. This phenomenon is attributed to the strong spontaneous and piezoelectric field along the (0001) orientation. Temperature dependent PL studies reveal the strongly zero-dimensional character of this QDs system. The experimental results show that, while for temperatur es lower than 50～60K and higher than 160K the peak energies follow the Varshni law, at the intermediate temperatures the energies decrease with increasing temperatures at a rate 6 times higher than that given by the Varshni law. The very similar phenomena were also observed in InAs QDs system. The temperature dependent PL and the AFM studies make sure that the QDs is successfully fabricated by PLT method.关键词：InGaN;quantum dots;optical property106|161|0更新时间：2020-08-11
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