防激光、防眩光PMMA材料的应用性能

以聚甲基丙烯酸甲酯（PMMA）为基材,加入防激光、防眩光吸收剂IR530、IR580、IR1065,制备了能有效吸收530nm、1060nm波长激光和500～580nm波长眩光的PMMA材料,对其防护性能、力学性能、耐老化性能和耐激光照射性能进行了研究。结果表明,防激光、防眩光PMMA材料对530nm波长激光的透过率为0．01％,对1060nm波长激光的透过率为0．02％,对500～580nm波长范围眩光的透过率小于等于0．1％,具有良好的防护性能;防激光、防眩光PMMA材料的冲击强度较高,为10．6kJ／m^2,且有良好的耐紫外老化性能。     

热处理工艺对减反膜性能的影响

以本实验室制备的高性能减反膜为研究对象,利用溶胶一凝胶法合成SiO：溶液,采用高速旋涂法制备纳米多孔SiO2减反膜,测试结果表明涂覆在白玻基材上的减反膜在可见光波段（400～800nm）范围内的透过率为94．6％±0．3％,其在405nm波长处的透过率达到1198．27％;同时进一步研究了热处理工艺在减反膜涂覆阶段对其减反性能的影响,研究发现：如果在基材表面涂覆一定厚度的减反膜,不同的热处理工艺对其的减反效果影响很大;如果热处理工艺选择不当,会使最终得到的涂层失去减反效能,甚至大幅度降低基材本身的透过率,为84．9％±1．1％。     

防眩光及紫外/蓝光防护功能涂层的制备及性能研究

以气相二氧化硅粒子及紫外吸收剂为功能助剂,氟碳改性高反应丙烯酸树脂为主体树脂,聚对苯二甲酸乙二醇酯(PET)聚酯膜为基材,采用湿法涂布工艺制备了具有防眩光和紫外/蓝光防护特性的功能涂层。研究了二氧化硅粒子含量、紫外吸收剂类型、所占比例以及涂层厚度对功能涂层性能的影响。结果表明,制备的UV固化吸光防眩光涂层兼具优异的防眩光和紫外/蓝光吸收性能,能有效改善显示屏幕表面发白和晃眼的问题。随着二氧化硅粒子含量的增加,涂层的雾度升高,同时光透过率和镜面光泽减小。紫外吸收剂HY-UV5具有最优的紫外/蓝光吸收性能。紫外吸收剂含量以及涂层厚度的增加,都能有效提高涂层的紫外/蓝光防护性能。此外,该涂层还具有优异的耐污和耐划伤性能。     

偶氮染料掺夹高分子聚合物PMMA的光信息存储性质研究

本文利用旋涂法(Spin-Coating)在单晶硅片和k9玻璃上分别制备了5-Br-PADAP,DMTAM,TADEB,DMTAA和5-Me-BTAEB五种杂环偶氮染料掺杂高分子聚和物聚甲基丙烯酸甲酯(PMMA)薄膜。测试了薄膜吸收,透过和反射光谱,通过椭圆偏振光谱计算了薄膜的光学常数。结果显示偶氮染料薄膜在450~600nm之间均有强而宽的吸收,5-Br-PADAP,DMTAM,TADEB,DMTAA参杂PMMA薄膜在514nm处具有较大的n值与较低的k值相匹配,有望作为与Ar+激光器相匹配的光盘记录介质;5-Me-BTAEB参杂PMMA薄膜在633nm处具有较大的n值与较低的k值相匹配,有望作为与He-Ne激光器相匹配的光存储记录介质材料。     

固相反应法制备高浓度掺杂Nd:YAG激光透明陶瓷及其性能

用固相反应和真空烧结技术,成功制备了高质量的4.0%(摩尔分数)Nd:YAG透明陶瓷,并对样品的显微结构、光学透过率、光谱性能和激光性能进行了表征.结果表明:样品的平均晶粒尺寸约为10 μm;样品(厚度为2.8 mm)在1 064 nm处的透过率高达79.5%;主吸收峰位于807 nm处,峰值吸收系数为13.9 cm-1,激光波长1 064 nm处的吸收系数为0.2 cm-1;主荧光发射峰位于1 064 nm处,荧光寿命为102 μs.用激光二极管(808 nm)端面泵浦Nd:YAG陶瓷样品(泵浦源最大输出功率为1 000 mW),获得了波长为1 064 nm的连续激光输出,输出功率17 mW(最大泵浦吸收功率为998 mW),斜率效率为6.1%,激光阈值约733 mW.     

SBA-15／PMMA杂化材料力学性能及热性能研究

采用溶胶一凝胶法制备了二维六方介孔结构的SBA-15,利用原位分散聚合法制备（SBA-15／0wt％DBP／PMMA,SBA-15／15wt％DBP／PMMA和SBA—15,25wt％DBP／PMMA）三种三维纳米网络结构的杂化材料。通过FT—IR、XRD、TEM、DSC和SEM等方法对SBA-15／DBP／PMMA杂化材料进行了表征。结果表明：DBP和SBA-15的加入对PMMA分子链的化学结构未造成任何影响,且SBA-15在PMMA基体中仍能保持介观有序结构;SBA-15对脆性PMMA具有较好的增强增刚作用,且DBP的含量越高,杂化材料拉伸强度和模量提高程度相对减小;三种杂化材料的rrg均随SBA-15含量的增加而提高,且DBP的含量越高,杂化材料的Tg提高幅度越小。     

单一窄波段光吸收涂层的制备及性能研究

以纳米吸光染料为光吸收剂,羟基丙烯酸酯为预聚物树脂,光学级聚酯(PET)薄膜为基材,采用湿法涂布的方式制备了660nm单一窄波段光吸收涂层。分别研究了光吸收剂添加量和涂层厚度对其光学性能的影响,并探索了吸收剂用量与涂层吸光度之间的关系。研究结果发现,随着光吸收剂添加量和涂层厚度的增加,涂层的全光线透过率急剧下降,雾度增大,光泽度降低;此外,吸收剂用量与涂层吸光度之间存在良好的线性关系,可为吸收剂用量的确定提供一定的理论依据。     

多波段光吸收涂层的制备及性能研究

以有机吸光染料(牌号为N660、N720和N890)为光吸收剂、羟基丙烯酸酯为预聚体树脂、光学级聚酯薄膜为基材,采用湿法涂布的方式制备了能同时对可见光、近红外光多个波段有吸收作用的光吸收涂层。研究结果表明:当w(N660)=0.40%、w(N720)=0.60%和w(N890)=0.80%(均相对于涂布液质量而言)时,所得涂层在660、720、890 nm处的光线透过率均低于0.10%,并且在380~600 nm可见光区的平均透过率超过50%,而且其力学性能(硬度2H、附着力5B)良好。     

蓝光吸收剂在PC中的应用探究

针对白光LED光源的富蓝化现象,采用蓝光吸收剂改性聚碳酸酯(PC)基材,利用蓝光吸收剂吸收高能量的蓝光并转化为热能或无害低能辐射释放出来,以消除白光LED光谱中的高能蓝光波段。结果表明,蓝光吸收剂改性PC材料后,可以有效减少各波长处的蓝光透过率,并且随着蓝光吸收剂添加比例的增加蓝光吸收效果增强;蓝光波段的吸收会造成光谱的缺失,造成光源的显色指数、色温、光通量的下降;不同类型的蓝光吸收剂改性PC树脂的蓝光吸收效果存在差异。     

Nd:YAG透明陶瓷的制备及激光输出

用溶胶-凝胶法制备了Nd3+掺杂摩尔分数为2.7%的Nd:AG粉体。采用真空热压和热等静压相结合工艺制备了Nd:YAG透明陶瓷。测试了样品的显微结构、透过光谱、吸收光谱、荧光光谱和激光性能。结果表明:样品的晶粒尺寸为2～10μm,晶界处存在少量气孔;1.7mm厚样品1064nm波长的透过率为78%;样品808nm处吸收峰对应的吸收系数为27.5cm-1;808nm泵浦的主荧光峰位于1064nm,荧光寿命为135μs;LD端面泵浦尺寸3mm×3mm×1.5mm的样品获得了最大输出功率170mW的激光输出,光-光转换效率为8%,斜效率为13.8%。     

Laser Initiation of Tris(carbohydrazide)metal(II) Perchlorates and Bis(carbohydrazide)diperchlorato‐copper(II)

The literature‐known tris(carbohydrazide)metal(II) perchlorates [M(CHZ)₃](ClO₄)₂ (MMg²⁺ ( 1 ), Mn²⁺ ( 2 ), Co²⁺ ( 3 ), Ni²⁺ ( 4 ), and Zn²⁺ ( 5 )) and the bis(carbohydrazide)diperchloratocopper(II) ( 6 ) were prepared and characterized by elemental analysis, IR and Vis/NIR spectroscopy. The sensitivities toward mechanical, thermal, and electrical stimuli were determined for all complexes 1 – 6 . Following, confined samples of 1 – 6 were irradiated with a monopulsed laser beam at a wavelength of 940 nm. The function times between beginning irradiation and complete decomposition (“breakout” at the end of the device) were measured. Further, the influence of light‐absorbing additives was investigated to proof if the laser initiation mechanism might be photothermal or photochemical. Addition of 1 % active carbon to the samples decreased the function time and the correlated initiation threshold enormously. This was an indication that the initiation mechanism seems to be thermal.     

Studies into Laser Ignition of Confined Pyrotechnics

Ignition tests were carried out on three different pyrotechnics using laser energy from the multimode output from an Ar‐Ion laser (av) at 500 nm and a near‐IR diode laser pigtailed to a fibre optic cable and operating at 808 nm. The pyrotechnics investigated were: G20 black powder, SR44 and SR371C. The confined ignition tests were conducted in a specially designed ignition chamber. Pyrotechnics were ignited by a free space beam entering the chamber through an industrial sapphire window in the case of the Ar‐ion laser. For the NIR diode laser, fibre was ducted through a block into direct contact with the pyrotechnic. The Ar‐Ion laser was chosen as this was found to ignite all three pyrotechnics in the unconfined condition. It also allowed for a direct comparison of confined/unconfined results to be made. The threshold laser flux densities to initiate reproducible ignitions at this wavelength were found to be between ∼12.7 and ∼0.16 kW cm⁻². Plotted on the ignition maps are the laser flux densities versus the start of ignition times for the three confined pyrotechnics. It was found from these maps that the times for confined ignition were substantially lower than those obtained for unconfined ignition under similar experimental conditions. For the NIR diode laser flux densities varied between ∼6.8 and ∼0.2 kW cm⁻². The minimum ignition times for the NIR diode laser for SR371C (∼11.2 ms) and G20 (∼17.1 ms) were faster than those achieved by the use of the Ar‐ion laser. However, the minimum ignition time was shorter (∼11.7 ms) with the Ar‐ion laser for SR44.     

Fluorescence Particle Counter for Detecting Airborne Bacteria and Other Biological Particles

We have constructed a laser-based particle counter that detects the fluorescence, as well as the elastic scattering, from individual airborne particles as they traverse a laser beam. This fluorescence particle counter (FPC) can detect fluorescence from μm-sized Bacillus subtilis spore agglomerates when illuminated with intense light at 488 nm from an argon ion laser, either ～ 0.7 kW cm^?2 extracavity or ～ 50 kW cm^?2 intracavity. We suspect that flavins in the spores are the molecules primarily responsible for the fluorescence, because the peak fluorescence emission of the biological materials at this excitation wavelength is in the range 530–550 nm, which is characteristic of flavins. Fluorescence from kaolin, hematite, and polystyrene particles was not detectable; the lack of fluorescence indicates that the FPC may be able to differentiate between biological and nonbiological aerosols. The FPC samples aerosol-laden air at a rate of ～ 1 mL s^?1, and is capable of measuring aerosol concentrations up to several thousand per milliliter. The FPC may be helpful in detecting and characterizing airborne bacteria and other airborne particles of biological origin.     

Sol-gel-derived spheres for spherical microcavity

Encapsulation of light to small spheres ensures the highest quality factor ( Q factor) to enhance the interaction between light and materials. In this Account, we describe the fabrication of micrometer-sized spherical particles of organic-inorganic hybrid materials to study the potential ability as a spherical cavity laser. The spherical particles prepared by the vibrating orifice technique included those of nondoped and doped with organic dyes and rare-earth-metal ions, and some of them were cladded with low-index-coating hybrid materials. Coating of the spheres was carried out by aiming at practical applications: high refractive index spheres from n D = 1.72 to 2.5 prepared by the technique and glass spheres of n D = 1.93. They were pumped by second harmonic pulses of a Q-switched Nd:YAG laser (532 nm wavelength) and CW Ar (+) laser (514 nm wavelength) to investigate as spherical cavity microlasers. The emission from spheres originated from the photoluminescence of dopants and Raman scattering of matrix materials. Lasing or resonant light emission from these spheres were performed by the direct-laser-light-pumping and the light-coupling techniques using an optical waveguide coupler.     

Raman spectroscopy of Kevlar fibres during deformation—Caveat emptor

It has been demonstrated that when aromatic polyamide fibres such as Kevlar 49 are subjected to mechanical deformation, significant frequency shifts are obtained for the peak position of the 1610 cm^?1 Raman band using both 632·8 nm and 488 nm laser radiation. Two earlier reports of the deformation of fibres in a 488 nm argon ion laser beam reported no such frequency shifts. It has been shown that this wavelength of laser light can degrade Kevlar fibres. This causes premature failure of the fibres through chain scission and the fibres break at low strains before significant levels of stress or strain can be achieved. Hence, the previous conflicts can be resolved and it has been demonstrated that simultaneous Raman spectroscopy and mechanical deformation is a powerful method of following the micromechanics of fibre deformation.     

Preparation of Ultrafine Fe–Pt Alloy and Au Nanoparticle Colloids by KrF Excimer Laser Solution Photolysis

We prepared ultrafine Fe–Pt alloy nanoparticle colloids by UV laser solution photolysis (KrF excimer laser of 248 nm wavelength) using precursors of methanol solutions into which iron and platinum complexes were dissolved together with PVP dispersant to prevent aggregations. From TEM observations, the Fe–Pt nanoparticles were found to be composed of disordered FCC A1 phase with average diameters of 0.5–3 nm regardless of the preparation conditions. Higher iron compositions of nanoparticles require irradiations of higher laser pulse energies typically more than 350 mJ, which is considered to be due to the difficulty in dissociation of Fe(III) acetylacetonate compared with Pt(II) acetylacetonate. Au colloid preparation by the same method was also attempted, resulting in Au nanoparticle colloids with over 10 times larger diameters than the Fe–Pt nanoparticles and UV–visible absorption peaks around 530 nm that originate from the surface plasmon resonance. Differences between the Fe–Pt and Au nanoparticles prepared by the KrF excimer laser solution photolysis are also discussed.     

近红外吸收功能染料的合成

以缩合剂1，5-二苯胺-戊-1，3-二烯盐酸化物与1，3，3，5-四甲基-2-亚甲基吲哚啉为主要原料合成了1，3，3．5，1’，3’，3’，5'-八甲基吲哚三碳菁近红外吸收染料，收率达61．5％，采用熔点测定、元素分析、IR验证了产品的结构。通过电子吸收光谱测得其最大吸收波长为760nm。     

Coating polycarbonate with acrylics will improve its weatherability

A problem of protecting polymers against weather influences is to concentrate the protective agents (UV-absorbers, antioxidants etc.) in the adequate place: the surface layer where photocxidative reactions primarily set in. The outstanding properties of polycarbonate (PC) are high levels of toughness and heat resistance whereas polymethylmethacrylate (PMMA) exhibits brilliant transparency and excellent weatherability. Mainly because of its higher spectral energy absorption from global radiation in the critical range from 300 to 400 nm wavelength PC is inferior to PMMA in weatherability: yellowing and erosion within a 20 μm surface layer of PC become visible after 5 years natural weathering. So the idea suggested itself to combine the favourable properties of these two polymers by coating PC with acrylics. As far as weathering results are available today this idea turned out to be very useful: the improvement in weatherability by coating PC regarding the yellowness index, light transmittance and surface erosion is a factor 2–3 in time and even more.     

Investigation of the initial growth of ultrananocrystalline diamond films by multiwavelength Raman spectroscopy

The initial growth phase of ultrananocrystalline diamond/amorphous carbon nanocomposite films (UNCD/a-C) has been investigated by scanning electron microscopy, atomic force microscopy and especially Raman spectroscopy. As due to resonance effects Raman spectra of carbon materials strongly depend on the excitation wavelength, a multiwavelength analysis has been performed with λ_exc ranging from the UV region (325 nm) over the visible range (488 and 514 nm) to the IR region (785 nm). In addition, a set of measurements has been performed with a confocal Raman microscope, i.e. depth resolved, with a wavelength of 532 nm. The samples investigated were deposited with constant parameters, the deposition time being the only parameter varied, resulting in film thicknesses from 100 to 500 nm. It turned out that the diamond fraction and also the grain boundary material do not vary during that stage whereas there are slight but distinct changes of the nature of the amorphous matrix which reflect, among others, in a shift of the graphite-related G band to higher wavenumbers and in an increase of the ratio of D and G bands with increasing film thickness. These changes are discussed in terms of the above mentioned resonance effects; the major changes are a transition of hydrogen containing sp² chains to hydrogen-free condensed sp² rings when the material is no longer in the surface region of the films but becomes incorporated within the film bulk.