Fe掺杂ZnO纳米球的光学特性

采用微乳液法制备了Fe掺杂ZnO纳米球材料(Zn1-xFexO,x=0.1),利用XRD和TEM对制备样品的结构、形貌进行了表征。在室温下,测得材料宽化的吸收光谱。用325nm的激光激发,测量了ZnO纳米球的光致发光光谱,低强度激发时观察到半峰全宽较窄、峰值波长为385nm的紫光峰和半峰全宽较宽、峰值波长约625nm的深能级发光峰;两峰的发光强度和峰位随着激发光功率密度的变化而变化,但变化规律不同。所合成材料的吸收和发光性质与Fe掺杂相关。     

水溶性CdTe量子点的稳态和纳秒时间分辨光致发光光谱

报道了以飞秒脉冲激光为激发光源的水溶性CdTe量子点(QDs)的稳态荧光光谱和纳秒时间分辨荧光光谱.实验发现CdTe量子点的荧光光谱峰值位置随激发波长变化发生明显移动，激发脉冲波长越长，荧光峰位红移越大.荧光动力学实验数据显示，在400nm和800nm脉冲激光激发下，水溶性CdTe量子点的荧光光谱中均含有激子态和诱捕态两个衰减成分，两者的发射峰相距很近，诱捕态的发射峰波长较长.在800nm脉冲激光激发下的诱捕态成分占总荧光强度的比重比400nm激发下的约高3倍，其相对强度的这种变化导致了稳态荧光发射峰位的红移. 关键词： CdTe 量子点 时间分辨 荧光光谱 上转换荧光     

口红的荧光和拉曼光谱特性的研究

人们消费方式的变化促使电商崛起,美妆市场呈爆发式增长,口红产品的安全成为关注焦点。面对品牌口红真伪问题,市场检测化妆品方法单一,对品牌口红的特征无针对性。采用三维荧光技术和共聚焦拉曼技术对某品牌真假口红的光谱性质进行了研究。三维荧光光谱显示五组口红均存在激发光峰值波长为320 nm左右,发射峰波长在372 nm附近的荧光(Ⅰ区)。A1, A2, A3, B1, B2和B3这6个样品中,激发光峰值波长为230 nm时会发出中心波长在400 nm左右的荧光,而在A4, A5, B4和B5这4个样品中,激发光峰值波长红移到250 nm左右,其荧光发射峰也发生了相应的红移,到450～470 nm(Ⅱ区)。此外,A5还存在激发光峰值波长550 nm,发射峰在590 nm附近的荧光;B1还存在270 nm激发,292 nm左右发射的荧光峰(Ⅲ区)。采用荧光强度相对法来定量分析,若都以Ⅰ区的荧光强度为1,口红不同色号间、同色号真假口红间的Ⅱ区和Ⅲ区的相对荧光强度显著不同。拉曼光谱显示正品口红中存在TiO₂的振动峰,也还存在大量的C—C, C—N,—CH₂和...     

镓置换铝对SrAl2Si2O8∶Eu2+晶体结构和发光特性的影响

采用高温固相法在弱还原气氛下制备了Sr0.955Al2－xGaxSi2O8∶Eu2+ (x=0～1.0)系列荧光粉,研究了Ga3+置换铝Al3+对晶体结构和光谱特性的影响.Ga3+进入SrAl2Si2O8晶格与Al3+发生类质同相替代使晶胞参量a、b、c、β和晶胞体积V都随Ga3+置换量呈线性增大,表明形成了连续固溶体.镓置换铝对晶胞参量c的影响最明显,b其次,a最小.Eu2+的宽带激发光谱位于230～400 nm,表观峰值位于350 nm,可由267 nm、305 nm、350 nm和375 nm四个峰拟合而成.随着镓置换量增加,较短波长的三个激发峰发生红移并且267 nm和350 nm峰强度减弱,305 nm峰强度明显增强,375 nm峰位和强度基本不变,表观激发峰半高宽由109 nm减小至98 nm,基本不随镓置换量变化.发射光谱位于380～600 nm为不对称宽带,可由406 nm和441 nm两峰拟合而成并且随Ga3+置换量增加线性红移,拟合发射光谱峰面积之比线性递增,Ga3+进入晶格对较长波长发射中心影响较大.Ga3+置换量为1.0 mol时,表观发射峰位从407 nm线性红移至422 nm,表观峰值随Ga3+置换量线性增大,半高宽由58 nm增加至79 nm.镓置换铝造成Eu-O距离变小,发光中心Eu2+所处晶体场增强,5d轨道能级分裂变大,最低发射能级下移.     

捕光天线LHCⅡ的荧光光谱特性研究

采用稳态荧光光谱技术在低温83 K下用波长为436 nm和507 nm的连续光激发对LHCⅡ进行研究,得到两种波长光激发下LHCⅡ的荧光光谱,并采用高斯组分光谱解析的方法,分别解析出四个谱带,结合吸收光谱和发射光谱分析,认为各自其中两个反映了两种光谱特性：Chl a683.6680/681、Chl a694.0690.0和Chl a/b671.4670.0和Chl a683.8680/681,其余两个长波长组分可能是Chl a分子主发射峰的振动副带.另外还将两种波长光激发下得到的荧光光谱特性做了比较,436 nm光激发下LHCⅡ发出的荧光强度要高于507 nm光的激发,这是由于接收436 nm光的Chl a分子数目多于接收507 nm光的类胡萝卜素分子,且436 nm下Chl a的吸收率也大于507 nm下类胡萝卜素的.从峰值上看,436 nm较507 nm光激励下的荧光光谱峰值产生红移,表明在不同波长光激励下,色素分子之间的能量传递途径是不同的.     

纳米银粒子的发光特性研究

研究了不同粒径和表面修饰的纳米银粒子的发光特性。研究结果表明,在不同波长光激发下,纳米银粒子在362 nm附近出现较强的发射峰,592和725 nm附近出现较弱的发射峰。随着激发光波长增加,发射峰强度下降,362 nm附近的发射峰红移。纳米银颗粒对210 nm的激发光最为敏感。发射峰波长与纳米银粒子表面修饰状态和颗粒尺寸关系不大,只是随着颗粒尺寸的减小,发射峰强度下降。随着狭缝宽度的减小,发射峰强度下降。随着纳米银胶浓度减少,发射峰逐渐聚拢合并为426 nm的单峰,且发射峰的强度先增强后逐渐下降。通过纳米银粒子表面光电子的吸收-再发射和表面能级杂化探讨了纳米银粒子的发光机理。     

非桥氧空穴发光中心对铁钝化多孔硅光致发光的影响

采用水热腐蚀法制备了铁钝化多孔硅样品,样品光致发光谱的荧光峰位于2.0eV附近,半峰宽约为0.40eV。激发波长从240nm增大到440nm的过程中,荧光峰先红移再蓝移,最后基本稳定,变化曲线呈勺型。通过分析15片发光多孔硅样品的统计结果,发现荧光峰逆转所对应的激发波长位于330nm附近,相应的激发光子能量约为3.8eV。样品光致发光谱随激发波长的勺型变化过程与≡Si—O↑和≡Si—O↑…H—O—Si≡两类非桥氧空穴发光中心共同作用时的发光行为一致。     

牛奶水溶液的荧光光谱研究

采集伊利、蒙牛公司生产的纯牛奶、高钙奶、高钙低脂奶,向5 mL去离子水中分别加入0.17 mL、0.20 mL、0.23 mL、0.26 mL、0.29 mL、0.32 mL、0.35 mL这6种牛奶样品,得到42份牛奶水溶液.采用日立F-4600荧光光谱仪测定样品在波长为315 nm、320 nm、325 nm、330 nm、335 nm、340 nm、345 nm激发光诱导下的荧光发射光谱,对所得荧光光谱进行Savitzky-Golay平滑、FFT低通滤波后,利用高斯分解法对荧光谱线进行分解,将每个荧光光谱分解为5个基元高斯峰.讨论了各种牛奶发射光谱的规律和变化趋势,结果表明:所有牛奶水溶液的各个基元高斯峰,在相同激发波长下,其峰值位基本不变,当激发波长变化时,所有基元高斯峰会随激发波长的增加而红移;高钙低脂奶在波长较长的激发光照射下,各个基元高斯峰强度均大于纯牛奶和高钙奶;牛奶的浓度对总荧光光谱的影响较小.     

胶体金纳米颗粒的荧光光谱特性

研究了胶体金纳米颗粒的荧光激发光谱和荧光发射光谱特性.增大激发光的波长,发射峰相应红移并在629nm达到最强,对应的灵敏激发波长为473nm.增加金纳米颗粒粒径,观察到发射谱的峰值先增大然后减小.发射峰产生的原因在于电子与带间空穴的复合导致非线性共振光散射.发射峰强度和金颗粒粒径的关系可以用表面等离子体震荡引起的局域场增强来解释,数值计算结果和实验结果能较好的吻合.     

瞬态功率光限幅实验

应用单脉冲时间分辨技术测量了富勒烯溶液瞬态功率光限幅特性。在激发波长为532nm,脉冲宽度为8ns,峰值功率密度达到180MW/cm²的条件下,其瞬态功率光限幅的开关速度约为5ns.     

Strong violet luminescence from ZnO nanocrystals grown by the low-temperature chemical solution deposition

The luminescence properties of zinc oxide (ZnO) nanocrystals grown from solution are reported. The ZnO nanocrystals were characterized by scanning electron microscopy, X-ray diffraction, cathodo- and photoluminescence (PL) spectroscopy. The ZnO nanocrystals have the same regular cone form with the average sizes of 100-500 nm. Apart from the near-band-edge emission around 381 nm and a weak yellow-orange band around 560-580 nm at 300 K, the PL spectra of the as-prepared ZnO nanocrystals under high-power laser excitation also showed a strong defect-induced violet emission peak in the range of 400 nm. The violet band intensity exhibits superlinear excitation power dependence while the UV emission intensity is saturated at high excitation laser power. With temperature raising the violet peak redshifts and its intensity increases displaying unconventional negative thermal quenching behavior, whereas intensity of the UV and yellow-orange bands decreases. The origin of the observed emission bands is discussed.     

Luminescence properties of spark-processed Si in air, O2, and N2 with low pressure

This paper reports the luminescence properties of spark-processed Si (sp-Si) prepared with different atmospheres such as air, O₂, and N₂ in low vacuum range (50-760 Torr). Three main luminescence bands are observed from spark-processed Si (sp-Si). In addition to the well-known two luminescence bands in the blue/violet peaking at 410 nm and green peaking at 500 nm, a novel UV luminescence band is detected for the sp-Si prepared in N₂. The temperature dependence of photoluminescence (PL) characteristics of the newly detected UV luminescence band is examined. Further studies of photoluminescence excitation (PLE) have been performed and origins of luminescence are discussed based on the experimental results.     

ZnO:Er3+纳米晶的制备及发光性质研究

为了探讨稀土Er3 与纳米ZnO基质之间的能量传递,利用化学方法制备了ZnO:Er3 纳米晶,测量了样品的X射线衍射谱(XRD)、光致发光谱(PL)和激发谱(PLE).X射线衍射结果表明,ZnO:Er3 具有六角纤锌矿晶体结构.室温下,在365 nm激发下,在ZnO宽的可见发射背景上,观测到了Er3 的激发态4S3/2(550 nm),2H11/2(521 nm)和4F5/2(456 nn)的特征发射.分析了ZnO:Er3 纳米晶的带边发射和稀土Er3 的特征发射的峰值强度随掺Er3 浓度的变化关系,比较了ZnO:Er3 与未掺杂的ZnO的光致发射峰值强度的变化,给出了稀土Er3 的激发态4S3/2→4I15/2,2H11/2→4I15/2和4F5/2→4I15/2的发射机制,证实了纳米ZnO基质与稀土Er3 离子之间存在能量传递.     

低能Co离子注入单晶ZnO的光致发光特性

采用离子注入法研究了Co离子注入ZnO晶体的光致发光效应。 对离子注入后的样品在Ar气保护下进行退火处理, 退火温度为700 ℃, 退火时间为10 min, 在其光致发光谱中观察到了406和370 nm的紫光发射峰。 对比了Co, Cu离子分别注入的ZnO晶体的光致发光谱, 观测到二者的光致发光谱类似。 同时, 研究了Co离子注入剂量对样品发光性质的影响, 结果表明随注入剂量的增加绿色发光中心逐渐向低能边偏移, 分析认为绿色发光中心的偏移与离子注入后ZnO晶体的禁带宽度发生改变相关。 In this paper, ion implantation techniques were used to study the photoluminescence(PL) of the Co implanted crystal ZnO. After Co ion implanted, the samples were annealed at 700 ℃ for 10 min in Ar gas flow. It was observed violet emission peak of 406 and 370 nm in the PL spectrum. The PL spectra of the ZnO crystal samples which were implanted by Co ions and Cu ions, respectively, have been compared and observed that the PL spectrum of the Co implanted ZnO is similar to that of the Cu implanted ZnO. We studied the influence of implantation dose on the PL of the Co implanted ZnO and found that the green luminescence centre shifted with increasing of implantation dose. It is concluded that the shift of the green luminescence centre is related to the change of ZnO band gap which was caused by ion implantation.     

反应溅射氧化锌薄膜的结构特点及性质

以金属Zn(纯度为99.99%)作为靶材,采用离子束反应溅射法在玻璃衬底上溅射沉积了一系列ZnO薄膜样品。通过对薄膜样品X射线衍射(XRD)谱的分析,发现尽管溅射条件不同,但是ZnO薄膜只沿(0002)晶面取向生长。衬底温度和溅射气体的氧分压对薄膜沿c轴取向生长有影响,其中衬底温度的影响较明显。溅射过程中发现衬底温度为360℃最适合(0002)晶面的生长,在此温度下溅射获得了完全沿c轴取向生长且衍射峰最强的ZnO薄膜。室温下测量了ZnO薄膜的发射光谱,发现薄膜在紫外区(364nm附近)、蓝绿区(470nm附近)有较强的发光峰,在紫光区(398nm附近)、蓝光区(452nm附近)和红外区(722nm附近)有较弱的发光峰。ZnO薄膜在空气中退火,对薄膜的结构、发光和电学性质都有一定影响。合适的退火温度可以促进薄膜沿c轴的取向生长;退火后ZnO多晶薄膜的晶粒比未退火的略大;退火使部分发光峰的位置发生偏移并使薄膜的发光强度增强;退火使薄膜的电阻率显著增大,薄膜的电阻率随氧分压的增大而增大。     

The investigation of photoluminescence centers in porous alumina membranes

To investigate the origin of blue photoluminescence (PL) in porous alumina membrane, we have prepared an anodic aluminum oxide film with a pore diameter of 40 nm in oxalic acid solution by a two-step anodization process. Our results show that the as-prepared alumina membrane is amorphous and exhibits a broad emission band peaking at around 452 nm with two sub-peaks located at 443 nm and 470 nm. As indicated by the PL excitation spectra, there are two excitation peaks which can account for the sub-peaks observed in the PL emission band. We have proposed that the broad emission band with two sub-peaks can be attributed to two luminescence centers in porous alumina membranes, namely, oxygen defects and oxalic impurities. Furthermore, we have rationalized that the two emission centers show similar influence on the PL band in the blue region based on a simple model. PACS 81.07.-b; 81.16.Dn; 79.60.Jv     

稀土Tb3+掺杂纳米ZnO的发光性质

ZnO是一种优良的直接宽带隙半导体发光材料(Eg=3.4 eV),具有优异的晶格、光学和电学性质,稀土离子掺杂浓度和热处理温度对ZnO∶Re3 纳米晶发光强度、峰位变化等光学性质具有重要影响.利用溶胶-凝胶法(Sol-Gel),在不同退火温度下,制备了不同浓度的ZnO∶Tb3 纳米晶.室温下,测量了样品的X射线衍射谱(XRD)、光致发光谱(PL)和激发谱(PLE).观察到纳米ZnO基质在520 nm附近宽的绿光可见发射和稀土Tb3 在485,544,584和620 nm附近的特征发射.通过ZnO基质可见发射强度和稀土Tb3 特征发射强度随Tb3 掺杂浓度、退火温度的变化关系,获得了5D4→7F5跃迁的绿色主发射峰最强的样品制备工艺参数,其退火温度为600℃、掺杂浓度为4 at%;给出了稀土Tb3 的激发态5D4→7F6(485 nm),5D4→7F5(544 nm)和5D4→7F4(584 nm)的发射机制;证实了稀土Tb3 与纳米ZnO基质之间存在双向能量传递.     

纳米晶ZnO可见发射机制的研究

利用化学沉淀法制备了纳米ZnO粉体,室温下测量了样品的光致发光谱(PL)、X射线衍射谱(XRD),给出了样品的透射电子显微照片(TEM).X射线衍射(XRD)的结果表明:纳米晶ZnO具有六角纤锌矿晶体结构,颗粒呈球形或椭球形.观察到二个荧光发射带,中心波长分别位于398 nm的紫带和510 nm的绿光带.发现随退火温度升高,粒径增大,紫带的峰值减弱、绿带的峰值增强.证实了纳米晶ZnO绿光可见发射带来自氧空位形成的施主和锌空位形成的受主之间的复合.     

Nonlinear Photoluminescence from ZnO Nanobelts

The nonlinear photoluminescence （PL） including second-harmonic generation （SHG） and the multiphoton luminescence （MPL） around 385 nm and 530 nm from ZnO nanobelts are investigated by using near-infrared excitations. The excitation wavelength dependence of MPL intensity reveals resonant energy transfer from SHG to MPL near the band gap excitation. The lifetime measurement of the MPL shows a much slower decay process of the defect emission, which results from the generation and recombination of both donors and acceptors on the disordered surface of the ZnO nanobelts.     

Photoluminescence from ZnO-SiO2 opals with different sphere diameters and thicknesses

We systematically investigated the photoluminescence (PL) and transmittance characteristics of ZnO-SiO₂ opals with varied positions of the stop-band and film thicknesses. An improved ultraviolet (UV) luminescence was observed from ZnO-SiO₂ composites over pure ZnO nanocrystals under 325 nm He-Cd laser excitation at room temperature. The UV PL of ZnO nanocrystals in SiO₂ opals with stop-bands center of 410 nm is sensitive to the thickness of opal films, and the UV PL intensity increases with the film thickness increasing. The PL spectra of ZnO nanocrystals in SiO₂ opals with stop-bands center of 570 nm show a suppression of the weak visible band. The experimental results are discussed based on the scattering and/or absorbance in opal crystals.