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,场诱导化学合成与制备材料 Materials Induce-synthesized & Prepared by Fields,管自生,南京工业大学材料科学与工程学院,,,包括：1）寻找新合成与制备方法的科学问题New Strategy；2）以适当的数量和形态合成材料的技术问题；3）已有材料的新合成方法（如Sol-gel）及其新形态（如Fiber、Film、Hierarchical Structures）的合成。,合成与制备(synthesize & Prepare),合成： 指促使原子、分子结合而构成材料的化学与物理过程。制备:研究如何控制原子与分子使之构成有用的材料。,场：包括磁场；电场；微波；等离子体；光；声场；重力场包括加热等；为材料的合成与制备针对反应提供反应能量或者提高反应速度或者改变反应途径等,,,5.电场合成 静电合成-静纺
Electric-field induced Synthesize &Electrospinning,主要内容(Main contents)：,1.光诱导合成 Light-induced Synthesize & Prepare,2. 微波等离子合成 Microwave & Plasma,3. 声波合成 Acoustic wave Synthesize,4. 重力场(Gravity field)在材料合成中的应用,,,Electromagnetic spectra,1. Introduction Lights,,,电磁波的范围,,,,分子光谱,,Molecular Spectra,,,2. 光与物质作用理论基础 Theories of Light-excited Materials,2.1原子分子受光激发 Excited Atom & Molecules
原子分子轨道；电子跃迁与辐射；分子能级图；原子分子受光激发后变化过程
2.2半导体受激光激发Excited Semicondutors
半导体跃迁；半导体受光激发的变化过程
2.3 金属受激光激发 Excited Metals,,,,,,,,,Figure Excitation and deexcitation process in molecule,Absorption
~ 10-15 s,S0,S2,Internal conversion
10-14-10-13 s,S1,T1,Fluorescence
10-9-10-5,,,Internal and External radiationless conversion,Intersystem crossing 10-6 s,Chemical reaction,Singlet excited state,Triplet excited state,Electron transfer（ms),Phosphorescence
10-5-10-3,Ground state,2.1原子分子受光激发,,,当基态分子的一个成对电子吸收光辐射后，被激发跃迁到能较高的轨道上，通常它的自旋方向spinning direction不改变，即S=0，则激发态仍是单线态，即“单线(重)激发态”；
如果电子在跃迁过程中，还伴随着自旋方向的改变，这时便具有两个自旋不配对的电子，电子净自旋不等于零，而等于1： S=1/2+1/2=1 其多重性： M=2S+1=3
即分子在磁场中受到影响而产生能级分裂，这种受激态称为“三线(重)激发态”；,,,原子核外电子受不同能量光子激发后，辐射过程,,,1)平动-平动转移 Translation-Translation
2)平动-转动转移 Translation-Rotation
3)转动-转动转移 Rotation-Vibration
4)振动-平动转动转移Vibration-Translation
5) 振动-振动转移 Vibration-Vibration
6)电子-振动转移 Electron-Vibration
7)电子-电子转移Electron-Electron,能量转移 Energy Transfer ：,Molecule orbits & Energy Levels
分子轨道与能级,2.1原子分子受光激发,,,Illumination of Electron Levels、 Vabriation Levels、 Rotation Levels,Electron Levels,Vabriation Levels,Rotation Levels,2.1原子分子受光激发,,,量子力学理论，分子的振 – 转跃迁也是量子化的或者说将产生非连续谱。因此，分子的能量变化 ΔE 为各种形式能量变化的总和：,运动的分子外层电子Outlayer Electrons - 吸收外来辐射 - 产生电子能级跃迁 – 分子吸收谱Molecular absorption spectra。,其中Ee 最大： 1-20 eV;
Ev 次之： 0.05-1 eV;
Er 最小： <0.05 eV,2.1原子分子受光激发,,,光源简介:普通光源;激光光源,太阳光模拟光源,,,,卤素灯,,,氙灯,紫外灯
高压汞灯,,,(一)光诱导合成法 Light-induced Synthesize,5. 其它光与材料合成,4.激光与材料化学合成,2. 光与物质作用理论基础 Principles,1.光与激光laser简介,3. 激光诱导化学反应
Laser-induced Chemical Reactions,,,1.激光简介 Introduction of Laser,近几十年来，随着激光技术的应用与发展，出现了一门崭新的边缘学科——激光化学
Laser chemistry 。
它和经典的光化学反应(Photochemistry )一样，是研究在光子Photon与物质相互作刚的过程中，物质激发态Exited States 的产生、结构、性能及其相互转化的一门学科。,,,特点: 1)具有亮度高、单色性好homochromatism、方向性好 Orientation ;
2) 高亮度，可以成为一种特殊热源;
利用这种热源:
直接加热Heating
蒸发Evaporation
解离Ionization 化学物质
使许多繁杂、艰难的化学操作变得简单可行；
3) 激光对原子、分子选择性相互作用Selective Reactions 提供了必要条件；
4)利用激光的方向性，可实现微区域Microarea的高温化学反应High-temperature Reactions。,,,激光器类型,1 CO2激光器 Carbon Dioxide Laser
2 He-Ne激光器 Helium-neon
3氩激光器:Argon laser
4 准分子激光器 excimer laser
5 固体激光器:钕激光器:neodymium laser/Nd laser
6 自由电子激光器 Free Electron Laser,,,CO2 Laser,属于气体激光器，分子激光器molecular laser
Wavelength 9-11m，最常见10.6 m
效率高 High efficiency
光束质量好 High Quality
功率范围大 （几瓦～几兆瓦）
运行方式多样
结构多样,,,,He-Ne Laser,气体原子激光器 Gas Atomic Laser
Output 输出谱线Spectrum line ：632.8nm，1.15 m，3.39 m，以632.8 nm为最常见
功率在mW级，最大1W
光束质量好，发散角可小于1mrad
单色性好Homochromatism ，带宽Bandwidth可小于20Hz
High stability,,,准分子激光器 Excimer laser,准分子指在激发态能够暂时结合成的不稳定分子
高重复率 可调谐 量子效率高、波长短，紫外到可见区,主要的准分子激光器,Excimer laser是一种紫外线化学激光器Ultraviolet Chemical Laser，常用于眼科手术及半导体工艺上。,,,YAG Solid Laser Yttrium Aluminum Garnet石榴石,Nd: YAG固体脉冲激光器主要性能指标：
Wavelength：213、266、355、532、1064 nm
Repeat Frequency：1-50 Hz（可调）
Energy：连续可调，Max 300 mJ （瞬间可融化、气 化多种材料及其表面）
脉宽Pulse width：3-5 ns,Energy Levels,(1) Changes of Atoms or Molecules Excited by Laser,Coulomb explosion 库仑裂解
Relativistic regime 相对论区间,Timescales of various electron and lattice processes in laser-excited solids. Each green bar represents an approximate range of characteristic times over a range of carrier densities from1017 to 1022cm–3.The triangles at the top show the current state-of the-art in the generation of short pulses of electromagnetic radiation: 1. 5 fs, 2. 120 fs (X-ray), 3. 0.5 fs (far ultraviolet).,Time Scales,碰撞电离,Figure Electron and lattice excitation and relaxation processes in a laser-excited direct gap semiconductor. CB is the conduction band and VB the valence band. d, Carrier distribution before scattering. e, Carrier–carrier scattering. f, Carrier–phonon scattering. g, Radiative recombination. h,Auger recombination. i, Diffusion of excited carriers.j,Thermal diffusion. k,Ablation. l, Resolidification or condensation.,a, Multiphoton absorption.
b, Free-carrier absorption.
c, Impact ionization.,,,中国“低空卫士”激光系统,,,,铝背钝化的太阳能电池,,,3.2,,用各种波长激光（红外、可见、紫外）诱发的化学反应大约有几百种。根据波长的不同，激光诱发化学反应的机理也不相同:
例如：红外激光Infrared Laser诱导化学反应:
红外敏化反应Infrared sensitized Reactions;
振动异构化反应Isomerization reaction;
红外异相催化反应Heterocatalysis;
红外诱导链反应Chain reaction;
红外光解范德华分子反应Photolysis Van der Waals Molecules;
红外多光子离解反应Multiphoton dissociation;
红外多光子离解反应要求激光必须有足够高的强度（至少108瓦/平方厘米）。,3. 激光如何诱导化学反应,1). 激光诱导化学反应是指在常温常压下不能进行但在激光的照射下可被诱发的化学反应。激光具有单色性、高强度和短脉宽等优越性能，是诱发光化学反应最理想的光源。,2) 激光诱导化学反应主要是指激光光解反应Laser-induced Photolysis以及由光解碎片splinter引起的后续化学反应，
例如，自由基Free radical或原子Atom，所产生的自由基又可以诱发链锁反应Chain reaction。,,,红外激光诱导化学反应中，激光的作用不是简单的热作用，而是红外光子同分子内的特定键或振动膜之间发生共振耦合。
红外激光诱导化学反应是一种定向的Orientation、低反应活化能Low activation energy的快速过程，具有高度的选择性Selectivity。
以三氯化硼分子为例，该分子的反对称伸缩振动v3(955cm-1) 。当用低功率的二氧化碳红外激光（λ＝10.55微米)辐照含有BCl3分子的混合气体时，将诱发化学反应。如混合气体为BCl3＋H2S，常温常压下不发生反应。在激光辐照时，使B-Cl键被激发，并发生以下反应过程：,,3BCl2SH→（BClS）3＋3HCl （BClS）3→B2S3＋BCl3,,,反应物分子被激发至电子激发态excited electronic state
绝大多数分子的离解能Dissociation energy在60～752.4 kJ.mol-1或3～7eV之间，这就需要波长为400～140 nm的紫外光辐照才行。
原则上讲，只要选择合适波长的激光，任何分子都能被光解，对同一分子来说，不同波长的激光辐照时有可能按不同的方式光解。例如，激光法生产氯乙烯（C2H3Cl）：,C2H4Cl·＋Cl·,C2H3Cl＋Cl·这是一个紫外激光诱导的自由基链反应radical chain reaction，关键是二氯乙烷被准分子激光光解所引发。激光诱导化学反应已用于10余种同位素的分离。,C2H4Cl2,,hv,C2H4Cl2＋Cl·→C2H3Cl2·＋HCl
C2H3Cl2· → C2H3Cl＋Cl·,紫外或可见激光光解反应
Ultraviolet & Visible Laser-induced Reactions,,,,,光电离 Photoionization,1）光直接电离 Directly Photoionization
分子电子直接被激发出
2) 自电电离
分子被激发到高于电离能的超激发态superexcited states，然后被微扰Disturbance电离一个离子ion和电子electron的状态,,,4.激光与材料制备 Materials of Laser-induced Synthesise,4.1激光催化化学反应 Laser-induced Catalytic Chemical Reactions
4.2激光诱导化学反应Laser-induced Chemical Reactions
4.3激光选择化学反应Laser-induced Selective ChemicalReactions
4.4激光显微化学反应 Laser-induced Microarea Chemical Reactions
4.5激光合成陶瓷粉体 Ceramic Powder of
Laser-induced Synthesis
4.6 脉冲激光沉积镀膜
Pulse Laser-induced Deposition Films
4.7其它高能射线High Energy Rays在材料合成中的应用,1. Laser-induced Catalytic Chemical Reactions,激光催化加快化学反应速度
表1列举了一些激光催化反应的效果。,,,4.2 Laser-induced Chemical Reactions,,,,,,,,,,,,光解制备氧化物半导体,Fast Synthesis of ZnO Nanostructures by
Laser-Induced Decomposition of Zinc Acetylacetonate,Presenting very attractive engineering properties like large exciton binding energy, photoluminescence, and piezoelectricity while being easily synthesizable in a plenty of different morphologies in single-crystal form, nanostructured zinc oxide has become one of the most studied semiconductor nanomaterials of the beginning of the 21st century.,Because of their great potential for the fabrication of new devices, in particular for optoelectronic and gassensing applications, 1D ZnO nanostructures have attracted much attention，oriented ZnO microtube arrays have been grown by solution chemistry for bio-/gas sensors by the selective UV light response.,Figure . Schematic depiction of the synthesis process. (A) Laser-induced decomposition of precursor solution. (B) Detail of the reaction zone with the different nanostructures obtained.,Solution Preparation.
A quantity of 0.4 g of zinc acetylacetonate hydrate [æsiti'læsitəu,neit]乙酰丙酮 (Zn(C5H7O2)2‚H2O, >95% purity) was manually mixed with 2 mL of deionized water and 2 mL of denatured ethanol (EtOH 85.47%, MeOH 13.68%, EtOAc 0.85%) for 5 min, forming a slurry of 0.355 M of Zn(AcAc)2‚H2O. The pH of the solution was measured to be 8.25. A few drops of the solution was then transferred to a fused quartz substrate,Laser Decomposition. A CO2 laser =10.6 m,,Figure (A) Low-magnification view of deposit grown at 20 W, 2 s;
(B) nanoparticle film;
(C) nanowires;
(D) nanorods grown at the same parameters.,Only a few seconds of irradiation, various zinc oxide (ZnO) nanostructures including nanorods and nanowires are formed near the center of the irradiated zone, surrounded by a porous thin film of ZnO nanoparticles,indeterminate shape with a very rough surface in the center.,nanoparticle aggregates,Ridges: nanowires nanorods,Different Zone,,,Figure . Influence of laser power on deposit morphology at a constant irradiation time of 10 s: (A) 5 W, 40 W/cm2; (B) 10 W, 80 W/cm2; (C) 15 W, 119 W/cm2; (D) 20 W, 159 W/cm2.,The type of structures produced and their localization on the substrate can be varied by selecting adequate irradiation time and laser power ranges.,crystalline whiskers
an average length: 1.3um
an average width of 167 nm,more randomly grown ZnO whiskers can be seen,,,Figure . SEM images of nanowires and nanonails grown with different laser irradiation parameters: (A and B) 20 W, 5 s; (C and D) 20 W, 2 s.,The type of structures produced and their localization on the substrate can be varied by selecting adequate irradiation time and laser power ranges.,UV lasing has been observed from ZnO whiskers and gas-sensing devices, and UV photodiodes were made from multipod-shaped nanorods.,Nanowires: 4.4 um further away from the center of the reaction zone,width of 47 nm,Nanoplates and nanonails with hexagonal tips between 100 and 300 nm wide,an assortment of
nanowire,,,Laser-Induced Mutual Transposition of the Core and the Shell of a Au@Pt Nanosphere,Noble-metal clusters and colloids with nanometer dimensions, exhibiting new optical and physical properties, have attracted a great deal of interest.,光诱导制备纳米晶金属,The design and controlled fabrication of nanostructured materials with functional properties have been extensively studied recently.,Nanostructured metals attract considerable attention scientifically as well as industrially because they can be used in diverse applications such as catalysts, magnetic devices, single electron transistors, and optoelectronics.,,,Figure. Illustration of processes taking place in a platinum-topped gold nanosphere during irradiation with 1064-nm laser pulses of 30 ps. The black indicates gold, while the gray indicates platinum. 1)The thermalized photon energy of platinum-plasmon resonances melts small platinum nanoparticles surrounding the core gold to convert the topped nanosphere into a smooth Au@Pt core-shell nanosphere. 2)Gold having the lower melting point melts and soaks out to the surface with further irradiation to produce a reversed core/shell Pt@Au core-shell nanosphere.,The optical properties of platinum, palladium, silver, and gold colloidal nanoparticles have received considerable attention because of this plasmon band.,Figure . TEM (A) and HRTEM images (B) of platinum-topped gold nanoparticles before (left) and after irradiation (right) with 1064-nm laser pulses of 30 ps for 120 min. Note that the actual particles transformed into the particles of the right are different from those of the left.,1) Aqueous 15-nm gold colloids of 50 mL having surfactant-free gold nanospheres
a gold atomic concentration of 1.0 mM were prepared by the citrate柠檬酸 reduction of HAuCl4。
2) platinum-topped gold nanoparticles were prepared by adding 21 mL of a 10 mM 2-day-aged H2PtCl6 aqueous solution and 8 mL of a 100 mL-ascorbic acid抗坏血酸 aqueous solution to 30 mL of the above-prepared gold colloids under vigorous stirring.,Experimental Sections,Citratic Acid,ascorbic acid,2-nm Pt,,,Figure 1. (A) Pictures of dried film 1 20, 40, and 60 min after the 355 nm laser irradiation. (B) Picture of formic acid-doped film (degree of doping 6 wt %) containing BP and HAuCl4 5 min afterthe 355 nm laser irradiation.,Acceleration of Laser-Induced Formation of
Gold Nanoparticles in a Poly(vinyl alcohol) Film,PVA (Mw ) (8.9-9.8)x104),
BP, 2-mercaptoethane sulfonate, 2-巯乙基磺酸,Polyvinyl alcohol,,,反应历程：Reaction mechanism,formic acid-doped,BPH• radical,PVA radical,,,Laser-Induced Self-Assembly of Pseudoisocyanine J-Aggregates Yoshito Tanaka
isocyanine [aisəu'saiəni:n]异花青 Pseudo [‘psju:dəu]伪-,Laser-Induced Organic Molecules Self-Assembly,A 1064 nm near-infrared (NIR) laser beam from a continuous wave
Nd-YAG laser was introduced into an inverted microscope and focused on a 520 nm spot by a 100 Plan-Neofluar objective lens,光诱导异构化反应,花青,,,4.3.激光选择化学反应 Laser-induced selective chemical reaction2,有些化学反应(热反应、经典光化学反应等)在通常条件下是一种方向，而在激光的作用下则会改变反应方向。或是在混合物中，或是同位素中，激光能激发某些原于、分子或同位素，而其余则不被激发，这种反应称之为定向反应或选择化学反应。激光选择化学反应已成了无机物分离提纯的全新技术手段。,,,激光选择分离稀土元素
稀土元素的化学性质是非常近似的。用化学方法分离，不但工艺繁杂，而且效率低，成本高。美国海军研究所Donohue等人用准分子激光器的紫外输出引发液相中的稀土元素反应，成功地分离了铕和铈。,,氧化态的变化会引起溶解度、可萃取性或反应性的变化，再用适当的化学方法就可达到分离之目的。例如，用氟化氩激光器193nm的紫外光输出激光激发Eu3+的水溶液，可使Eu3+还原为Eu2+，再用SO42-沉淀，而铈留在溶液之中。反应为：
在0.01mol/L的Ce稀土溶液中进行实验，用250nm的激光照射稀土溶液，就会发生光氧化反应，再用IO3-沉淀，反应为：,,,,,4,,,利用激光的方向性可实现显微化学反应，这在集成电路和半导体器件的生产中可用于修补、扫描无掩膜光刻、欧姆接触及局部掺杂等。,4.4 激光显微化学反应,（a)激光化学沉积（LCVD）
化学气相沉积(CVD)是晶体生长和薄膜生长的一种有效技术， 它是通过加热置于氧化或还原气氛中的基板进行气相沉积，通常在整个基板表面上都有沉积发生。
CVD特点：基板进行长时间的高温加热，因此不能避免杂质的迁移和来自基板的自掺。
LCVD优点：不用直接加热整块基板，可按照需要进行沉积。空间选择性好，甚至可使薄膜生长限制在基板的任意微区上。局部可控沉积,,,激光沉积与化学气相沉积相比具有很多优点：
(1)激光学沉积面积只有10-4 cm2，而化学气相沉积则是数个cm2。
(2) SiH4的压力比化学气相沉积高2-3数量级。沉积速率比化学气相沉积快2-3数量级。,SiH4/Ar,CO2激光作用热源,,石英片作基板,1000-1200℃,硅沉积在石英片,Si-SiO2,美国南加利福尼亚大学Christensen,,,4.5 激光合成精细陶瓷粉末,,m,美国麻省理工学院的能量及材料加工实验室的J.Haggar等人,CO2激光器(10.6m),SiH4和NH3混合气体
(强吸收10.6 m光子),,在同样条件下也可合成SiC粉末：,m,氮化硅是一种重要的结构陶瓷材料。它是一种超硬物质，本身具有润滑性，并且耐磨损，为原子晶体；高温时抗氧化。而且它还能抵抗冷热冲击，在空气中加热到1000℃以上，急剧冷却再急剧加热，也不会碎裂。,,,激光合成精细陶瓷粉末的基本原理：
1）利用了反应物对激光的强吸收性，用吸收的能量引发气相化学反应，生成固态精细粉末。
2）生成物最好对激光不吸收或很少吸收。
特点：a.反应区界限很分明，而且范围小；
b. 具有反应气体均匀快速的加热率；
c. 具有生成物的快速冷却率；
d. 具有反应温度的阈值； 当温度高于这一值时，反应快速进行，均匀成核。,,综上所述：激光在无机化学中的应用是非常广泛的。
随着现代科学技术的进步和激光技术的发展，
光技术一定会在无机化学中得到更广泛的应用。,,,4.6 脉冲激光沉积镀膜 Pulse Laser-induced Deposition Films,Pulse Excimer laser所产生的高功率脉冲激光束聚焦作用于靶材料表面，使靶材料表面产生高温及熔蚀，并进一步产生高温高压等离子体（T≥104K）High Temperature and High Pressure Plasma, 这种等离子体定向Orientation局域膨胀发射并在衬底上沉积而形成薄膜。,,脉冲激光沉积镀膜示意图,优点：,①易于保证镀膜后化学计量比的稳定
②反应迅速，生长快。
③定向性强、薄膜分辩率高，能实现微区沉积
④生长过程中可原位引入多种气体
⑤易制多层膜和异质膜
⑥易于在较低温度下原位生长取向一致的结构和外延单晶膜,Scanning electron microscopy micrographs of the deposited films revealed that PTFE grains were uniformly grown on the cotton surface with an average grain size of about 50–70 nm.,using a KrF 248 nm excimer laser,The laser energy was fixed at 1 J/cm2,Pulsed laser deposition (PLD) was utilized to deposit polytetrafluoroethylene (PTFE) thin films on cellulosic cotton substrates at room temperature.,a cellulosic cotton fiber,PTFE deposited on a cotton fiber.,,,The PTFE-coated fibers showed superhydrophobic properties as evidenced by a water contact angle of 151- compared to a 0- contact angle for pristine cellulosic cotton substrates.,
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