飞秒激光作用下金掺杂硅酸盐玻璃的光致晶化研究

研究了金掺杂硅酸盐玻璃在飞秒激光辐照和热处理作用下的光致晶化行为，分析探讨了其机理和激光辐照条件的影响.吸收光谱测试表明玻璃内部析出金纳米颗粒. 金纳米颗粒掺杂玻璃在近共振纳秒脉冲作用下显示了强的光限幅效应, 且改变飞秒激光诱导参数可改变该复合玻璃的光学非线性. 关键词： 光致晶化 飞秒激光 金纳米颗粒 硅酸盐玻璃 光限幅     

高重复频率激光在非掺杂氧化铋玻璃中诱导TiO2晶体析出

使用聚焦后的800nm,150fs,250kHz的高重复频率飞秒脉冲激光研究它在非掺杂氧化铋玻璃内部三维选择性的诱导析晶. 通过拉曼光谱测定发现析出的晶体是TiO2且为金红石相.研究表明, 经过250kHz的飞秒激光辐照一段时间后,玻璃内部由于脉冲能量的连续累积会使得激光辐照区域出现热累积效应,达到玻璃的析晶温度后诱导晶体析出.通过连续移动激光束,可以实现连续刻写TiO2晶线,通过EDX测试显示聚焦区域出现了由于热累积效应而形成热驱动使得离子发生迁徙.实验结果表明这种方法适用于在透明介质材料中三维选择性刻写晶体以制备集成光学器件.     

高重复频率激光在非掺杂氧化铋玻璃中诱导TiO2晶体析出

使用聚焦后的800nm,150 fs,250 kHz的高重复频率飞秒脉冲激光研究它在非掺杂氧化铋玻璃内部三维选择性的诱导析晶.通过拉曼光谱测定发现析出的晶体是TiO2且为金红石相.研究表明,经过250 kHz的飞秒激光辐照一段时间后,玻璃内部由于脉冲能量的连续累积会使得激光辐照区域出现热累积效应,达到玻璃的析晶温度后诱导晶体析出.通过连续移动激光束,可以实现连续刻写TiO2晶线,通过EDX测试显示聚焦区域出现了由于热累积效应而形成热驱动使得离子发生迁徙.实验结果表明这种方法适用于在透明介质材料中三维选择性刻写晶体以制备集成光学器件.     

封面说明

纳米粒子的尺寸与形状控制以及图案化是近年来国际上纳米科技领域的一个研究热点．最近发现了通过利用光的波长以及偏振方向可以控制溶液中形成的纳米粒子的尺寸和形状．我们利用超快激光实现了透明介质内部有空间选择性的纳米粒子的析出和控制．可以在一块无色透明的介质中通过激光照射和热处理，在透明介质中任何位置析出一定尺寸的纳米粒子，并且可以通过激光的二次照射将纳米粒子擦除．     

飞秒激光所致金纳米粒子析出的玻璃非线性吸收

依据Z-scan技术,使用波长532nm的纳秒脉冲,研究了通过聚焦的飞秒脉冲诱导并辅以热处理得到的金纳米粒子析出的玻璃的非线性吸收.观察到金纳米粒子析出的玻璃具有饱和吸收特性.根据局域场效应,对实验结果拟合,得到在接近表面等离子体共振激发情况下,金纳米粒子三阶极化率虚部分别为Imχ(3)m=57×10-7esu.玻璃样品中金纳米粒子的非线性响应主要起源于热电子贡献. 关键词： 带内跃迁 带间跃迁 热电子贡献     

飞秒激光诱导Li2O-Nb2O5-SiO2玻璃析晶拉曼谱研究

通过使用波长 800nm、重复频率 250kHz的飞秒激光脉冲聚焦进Li2O-Nb2O5-SiO2组分的玻璃内部,空间选择性诱导出铌酸锂微晶.为了进一步地研究辐照区域晶体的生长机制,使用显微拉曼光谱仪分析了玻璃样品辐照区域不同位置的结构变化.研究表明,在飞秒激光辐照一段时间后的聚焦区域,由于非线性效应和热累积效应形成了一个高温辐射梯度场,在激光辐照中心区域超过玻璃的析晶温度而促使玻璃熔融析晶.     

飞秒激光烧蚀合成Y_2O_3∶Pr~(3+),Yb~(3+)上转换发光材料

利用飞秒激光烧蚀方法合成了Y2O3∶Pr3+,Yb3+纳米颗粒并对其上转换发光性质进行了研究。对合成产物的形貌分析显示,在一定的激光烧蚀功率密度下,即可制备出小尺寸的纳米颗粒,提高激光功率密度可以得到更高的纳米颗粒产量,所获得的纳米颗粒尺寸小于50 nm。荧光测试结果表明,Y2O3∶Pr3+,Yb3+纳米颗粒具有510 nm为中心的上转换发光带,上转换发光随纳米颗粒数量的增加而增强。     

Ag掺杂对高重复频率飞秒激光诱导Gd2O3-MoO3-B2O3玻璃析晶

将800nm高重复频率250 kHz的飞秒激光分别聚焦到掺Ag和没有掺Ag的Gd2O3-MoO3- B2O3玻璃表面,研究掺Ag对飞秒激光诱导析晶的影响。对激光辐照的区域显微拉曼分析发现对于没掺Ag玻璃,诱导玻璃析晶需要的激光功率和辐照时间比掺了Ag的玻璃要大要长,这说明Ag的掺入促进了玻璃的析晶。其机理可能为飞秒激光的多光子吸收效应,导致玻璃基质中桥氧键断裂,产生非桥氧空穴和自由电子,玻璃中的Ag离子捕获电离出来的电子被还原成Ag原子,Ag原子在热动力的驱动下移动聚集形成银纳米颗粒,形成的银纳米团簇作为核促进了钼酸盐玻璃的析晶。     

Ag掺杂对高重复频率飞秒激光诱导Gd_2O_3-MoO_3-B_2O_3玻璃析晶的影响

将800nm高重复频率250kHz的飞秒激光分别聚焦到掺Ag和没有掺Ag的Gd2O3-MoO3-B2O3玻璃表面,研究掺Ag对飞秒激光诱导析晶的影响.对激光辐照的区域显微拉曼分析发现对于没掺Ag玻璃,诱导玻璃析晶需要的激光功率和辐照时间比掺了Ag的玻璃要大要长,这说明Ag的掺入促进了玻璃的析晶.其机理可能为飞秒激光的多光子吸收效应,导致玻璃基质中桥氧键断裂,产生非桥氧空穴和自由电子,玻璃中的Ag离子捕获电离出来的电子被还原成Ag原子,Ag原子在热动力的驱动下移动聚集形成银纳米颗粒,形成的银纳米团簇作为核促进了钼酸盐玻璃的析晶.     

飞秒激光诱导材料内部三维光功能微结构新进展

飞秒激光是近年来获得迅速发展的一种超快激光．超短脉冲和超高电场强度是它的两个特征．飞秒激光已广泛用于物理化学反应的动力学过程分析和热效应可忽略的超精细加工．利用飞秒激光与材料的非线性相互作用，还可以实现透明材料内部有空间选择性的三维调控光功能微结构．文章重点介绍了在可擦重写三维超高密度光存储、立体彩色内雕、可集成超快光开关等方面的应用和国内外相关领域的最新进展，并展望了应用前景。     

Effect of Ultrashort Pulsed Laser and X-Ray Irradiation on Au+ -Doped Glass

Au nanoparticles were precipitated inside Au+-doped glass samples after irradiation by femtosecond laser or x-ray. Femtosecond laser and X-ray irradiation result in decreasing of anneal temperature and critical size for the precipitation of Au nanoparticles.     

One-step synthesis of silica-coated magnetite nanoparticles by electrooxidation of iron in sodium silicate solution

In the present study, solid-solution gold?Cplatinum (Au?CPt) nanoparticles with controllable compositions were fabricated by high-intensity femtosecond laser irradiation of an aqueous solution of gold and platinum ions without any chemicals and complicated processes. Transmittance electron microscopy revealed that the single nanometer-sized particles were fabricated by femtosecond laser irradiation of mixed aqueous solutions of gold and platinum ions. The crystalline structure of nanoparticles was characterized by electron and X-ray diffractions. Contrary to the bulk Au?CPt binary systems, which commonly contain a pair of diffraction peaks between pure gold and platinum peaks because of its large miscibility gap in phase diagram, or mixture of Au and Pt, the diffraction peaks of Au?CPt nanoparticles fabricated in the experiment showed a characteristic of the fcc-type lattice. Moreover, the diffraction patterns shifted monotonically from the peak position of pure gold to that of pure platinum as the fractions of platinum ions in the solution were increased. These observations strongly imply that the Au?CPt nanoparticles were solid solution with intended compositions. This technique is not only simple and environmentally friendly, but also applicable to other binary and ternary systems.     

Erratum to Formation and control of Au and Ag nanoparticles inside borate glasses using femtosecond laser and heat treatment

We report the spectroscopic properties of femtosecond laser-irradiated sodium-alumino-borate glass doped with silver and gold ions. We precipitated gold and silver nanoparticles by laser irradiation and annealing at 400°C for 30 min. The irradiation and annealing treatment produced different absorption and emission characteristics in Au³⁺ doped and Au³⁺, Ag⁺ codoped glasses, and the possible mechanisms of the observed results are discussed. The size of the nanoparticles was estimated by TEM and absorption band analysis.     

Nanocomposite ZnO/Au formation by pulsed laser irradiation

The ZnO/Au nanocomposite formation involves synthesis of Au and ZnO colloidal solutions by 532 nm pulse laser ablation of metal targets in deionized water followed by laser irradiation of the mixed colloidal solution. The transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) images show evolution of spherical particles into ZnO/Au nanonetworks with irradiation time. The formation mechanism of the nanonetwork can be explained on the basis of near resonance absorption of 532 nm irradiation by gold nanoparticles which can cause selective melting and fusion of gold nanoparticles to form network. The ZnO/Au nanocomposites show blue shift in the ZnO exciton absorption and red shift in the Au plasmon resonance absorption due to interfacial charge transfer.     

Laser-Assisted Formation of Elongated Au Nanoparticles and Subsequent Dynamics of Their Morphology under Pulsed Irradiation in Water

The processes of laser-assisted formation of elongated Au nanoparticles and their subsequent agglomeration and fragmentation have been experimentally investigated. Elongated gold nanoparticles were formed by laser ablation of a solid target in water. IR radiation of ytterbium-doped fiber laser with a pulse width of 200 ns and a pulse energy of 0.5 to 1 mJ was used to this end. The extinction spectra and transmission electron microscopy images indicate the formation of elongated gold nanoparticles. The interaction of laser radiation with aqueous colloids of elongated nanoparticles in dependence of the pulse energy and exposure time has been analyzed. Possible processes of laser-assisted formation of elongated Au nanoparticles and their subsequent transition from agglomeration to fragmentation of gold nanoparticles, induced by laser irradiation are discussed.     

Silicon nanowires synthesized by vapor–liquid–solid growth on excimer laser annealed thin gold film

The fabrication of Si nanowires has been demonstrated using excimer laser annealed thin gold film as the catalyst and vapor–liquid–solid (VLS) growth. Au nanoparticles with mean diameters of 12, 13 and 15 nm were formed by excimer laser annealing (ELA) of Au film with thickness of 2.5, 5 and 10 nm, respectively. The results show that the silicon nanowires (SiNWs) with desired diameter can be obtained by controlling the Au film thickness and laser power density.     

Room temperature synthesis of an optically and thermally responsive hybrid PNIPAM–gold nanoparticle

Composites of metal nanoparticles and environmentally sensitive polymers are useful as nanoactuators that can be triggered externally using light of a particular wavelength. We demonstrate a synthesis route that is easier than grafting techniques and allows for the in situ formation of individual gold nanoparticles encapsulated by an environmentally sensitive polymer, while also providing a strong interaction between the polymer and the metal particle. We present a one-pot, room-temperature synthesis route for gold metal nanoparticles that uses poly-N-isopropyl acrylamide as the capping and stabilizing agent and ascorbic acid as the reducing agent and achieves size control similar to the most common citric acid synthesis. We show that the composite can be precipitated reversibly by temperature or light using the non-radiative decay and conversion to heat of the surface plasmon resonance of the metal nanoparticle. The precipitation is induced by the collapse of the polymer cocoon surrounding each gold nanoparticle, as can be seen by surface plasmon spectroscopy. The experiments agree with theoretical models for the heat generation in a colloidal suspension that support fast switching with low laser power densities. The synthesized composite is a simple nanosized opto-thermal switch.     

Synthesis of multiple shapes of gold nanoparticles with controlled sizes in aqueous solution using ultrasound

Effects of concentration of stabilizer (sodium dodecylsulfate: SDS) and ultrasonic irradiation power on the formation of gold nanoparticles (Au-NPs) were investigated. Au-NPs with multiple shapes and size were synthesized by controlling the concentration of stabilizer and ultrasonic irradiation power. The shapes and size of Au-NPs were controlled by changing either the ratio of Au(III) ion/SDS or the power of ultrasonic irradiation. The multiple shapes and size distribution of Au-NPs are dependent on not only the ratio of Au(III) ion/SDS but also ultrasonic irradiation power. The sonochemically synthesized Au-NPs were characterized by TEM and UV-vis spectroscopy.     

A novel method of nanocrystal fabrication based on laser ablation in liquid environment

Metal nanoparticles can be prepared by a novel technique that consists of the laser ablation of a solid target immersed in a water solution of a metal salt. Silicon was chosen as the most adequate target to synthesize silver and gold nanoparticles from a water solution of either AgNO₃ or HAuCl₄. The influence of both the silver nitrate concentrations and the irradiation time of the Si target on the optical properties of the Au and Ag nanoparticles have been investigated. The crystalline nature of the metal nanoparticles has been determined by X-ray diffraction (XRD). Average size and particle size distribution have been measured by means of TEM. The absorbance spectra show the characteristic band of the surface resonant plasmon of silver and gold nanoparticles.