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排序方式: 共有343条查询结果,搜索用时 46 毫秒
11.
12.
Paramita Saha Chowdhury 《Journal of luminescence》2007,124(2):327-332
Here, we have examined the role of capping agent on the optical properties of CdS nanoparticles by steady-state and time-resolved photoluminescence (PL) spectroscopy. The estimated particles sizes are 3.45, 2.5 and 2.39 nm for uncapped, capped with silica (SiO2) and thiosalicylic acid (TSA), respectively. The absorption and emission spectra show a clear blue shift to shorter wavelengths in presence of TSA- and SiO2-capped nanoparticles. It is found that the average decay time 〈τ〉 are 6.24, 4.54 and 2.84 ns for uncapped, capped with SiO2 and TSA nanoparticles, respectively. Our analysis suggests that the hole or the electron is trapped on thiol molecule of TSA or hydroxyl group of SiO2, then radiative recombination of the electron and hole is delayed, resulting in strong quenching of PL efficiency. 相似文献
13.
X.Q. Meng D.Z. Shen J.Y. Zhang Y.M. Lu Z.Z. Zhang X.W. Fan 《Solid State Communications》2005,135(3):179-182
High quality vertical-aligned ZnO nanorod arrays were synthesized by a simple vapor transport process on Si (111) substrate at a low temperature of 520 °C. Field-emission scanning electron microscopy (FESEM) showed the nanorods have a uniform length of about 1 μm with diameters of 40-120 nm. X-ray diffraction (XRD) analysis confirmed that the nanorods are c-axis orientated. Selected area electron diffraction (SAED) analysis demonstrated the individual nanorod is single crystal. Photoluminescence (PL) measurements were adopted to analyze the optical properties of the nanorods both a strong UV emission and a weak deep-level emission were observed. The optical properties of the samples were also tested after annealing in oxygen atmosphere under different temperatures, deep-level related emission was found disappeared at 600 °C. The dependence of the optical properties on the annealing temperatures was also discussed. 相似文献
14.
Song Dang Jiangbo Yu Lining Sun Jing Feng Hongjie Zhang 《Journal of luminescence》2011,131(9):1857-1863
The ligand 1-(2-naphthyl)-4,4,4-trifluoro-1,3-butanedionate (Htfnd) has been employed to synthesize six novel ternary-lanthanide complexes in which the synergic ligands were 1,10-phenanthroline-5,6-dione (dione) and 4,5-diazafluoren-9-one (dafone), respectively. Two series of complexes Ln(tfnd)3dione and Ln(tfnd)3dafone (Ln=Ho, Pr, Tm) were obtained. These complexes were characterized by elemental analysis, Fourier Transform Infrared spectra and diffused reflectance. After ligand-mediated excitation, Ln(tfnd)3dione and Ln(tfnd)3dafone all show the characteristic NIR luminescence of the corresponding Ln3+ ions (Ln=Ho, Pr, Tm). This can be attributed to the efficient energy transfer from ligands to central Ln3+ ions, via an antenna effect. The indirect energy transfer in the complexes has been investigated and the differences in the luminescence intensity between Ln(tfnd)3dione and Ln(tfnd)3dafone were discussed in detail. The excellent luminescent performances enable these NIR-luminescent complexes to have potential applications in optical amplification operating at 1300 or 1500 nm. 相似文献
15.
Luminescence efficiency of self-activated CaWO4 under 147 nm vacuum ultraviolet (VUV) radiation excitation is about 90% of that of BaMgAl10O17:Eu2+ (BAM), the commercial blue plasma display panel (PDP) phosphor. However, the color purity and the particle size of the former needs substantial modification before it can be considered for application in PDP. CaWO4:Tm exhibits Tm3+ emission peaks in the blue region due to energy transfer from WO4 to Tm3+ ions but the overall emission intensity under 147 nm excitation is reduced when compared to that of CaWO4. 相似文献
16.
Chunting Wu Youlun Ju Qiang Wang Zhenguo Wang Baoquan Yao Yuezhu Wang 《Optics Communications》2011,284(4):994-998
The solid-state, tunable, narrowband, high pulse energy and high reliability lasers are attractive source for LIDAR system. In this paper, we demonstrated a diode pumped injection-seeded 2 μm Tm:YAG laser. By inserting two F-P etalons into the laser cavity, linear-polarized single-frequency seed-laser was achieved at a wavelength of 2013 nm, with a maximum output power of 60 mW. Long-term and short-term frequency stability for the seed-laser were 1.27 × 10− 7 and 97 Hz/μs, respectively. High power Q-switched laser was operated using a bowtie cavity, the bidirectional output of which was favorable for the injection-seeded. After injecting the seed-laser to the power-laser, single-frequency, nearly transform-limited pulsed 2 μm laser was obtained. As much as 2.0 mJ output energy was achieved at an operating repetition rate of 15 Hz, with a pulse width of 356.2 ns. 相似文献
17.
Li Li Wang XiaochunWei xiantao Chen YonghuGuo Changxin Yin Min 《Physica B: Condensed Matter》2011,406(3):609-613
Lutetium oxide nanopowders codoped with Tm3+ and Yb3+ were synthesized by the reverse-strike co-precipitation method. Effects of precipitant solution pH on the structural, morphological and upconversion luminescent properties of Lu2O3:2%Yb, 0.2%Tm nanopowders had been investigated. The results show that pH value of the precipitant (NH4HCO3) solution has a significant effect on the particle size, morphology and upconversion emission intensity of the Lu2O3:2%Yb, 0.2%Tm nanopowders. All the samples obtained from different pH value of precipitant solution can be readily indexed to pure cubic phase of Lu2O3, indicating good crystallinity. The upconversion emission intensity of Lu2O3:2%Yb, 0.2%Tm nanopowders obtained from the precipitant solution with pH=11 is the strongest. The enhancement of the upconversion luminescence is suggested to be the consequence of reducing the number of OH− groups and the enlarged nanopowder size. The strong blue, weak red and near infrared emissions from the prepared nanopowders were observed under 980 nm laser excitation, and attributed to the 1G4→3H6, 1G4→3F4 and 3H4→3H6 transitions of Tm3+ ion, respectively. 相似文献
18.
B. J. Garcia J. Martinez J. Piqueras 《Applied Physics A: Materials Science & Processing》1990,51(5):437-445
GaAs melting simulations with a pulsed ruby laser are reported. The presence of a thin metal layer deposited on the GaAs surface gives rise to a reduction in the melting threshold and to an increase of melted depths when compared with nude GaAs surfaces. Melting thresholds around 0.3 J/cm2 for nude GaAs surface and slightly below 0.25 J/cm2 for GaAs covered with a 120 Å tin layer are predicted in reasonable agreement with experimental results. 相似文献
19.
Cr,Tm:YAG晶体中的能量转移 总被引:1,自引:0,他引:1
通过对Cr:YAG、Tm:YAG和Cr,Tm:YAG晶体吸收光谱和发射光谱的比较,研究了Cr,Tm:YAG晶体中的能量转移过程.指出Cr3+→Tm3+能量转移过程中,无辐射能量转移占绝对优势. 相似文献
20.
B. Baronti F. Cornacchia A. Di Lieto P. Maroni A. Toncelli M. Tonelli 《Optics and Lasers in Engineering》2003,39(3):277-282
We present the results obtained with a Tm,Ho : YLF crystal, grown in the new crystals growth facility realized in the Dipartimento di Fisica of the Università di Pisa. The 2 μm laser performance has been studied for three different pump sources, a Ti : Sapphire, a diode—tuned at 792.7 nm—and a Co : MgF2 laser, tuned at 1.682 μm. 相似文献