铟酞菁/聚甲基丙烯酸甲酯复合物固体光限幅器性能

将在溶液中表现出优良非线性光学和光限幅性能的铟酞菁及其二聚物嵌入到非光学活性的聚甲基丙烯酸甲酯(PMMA)中, 用传统的旋转涂膜法制备得到具有较高光学质量的复合物薄膜, 用开孔Z-扫描方法在532 nm 处研究了复合物薄膜材料的线性光学和非线性光学性能. 结果表明, 无论是铟酞菁单体还是轴向氧桥联的铟酞菁二聚物, 其PMMA复合材料的光限幅性能均显著优于相应的酞菁分子在溶液中的光限幅性能.     

一种可溶性氯铟酞菁化合物的光限幅性能研究

本工作通过无中心金属酞菁合成了可溶性金属酞菁化合物--四-α-(2-乙基丁氧基)氯铟酞菁,用纳秒脉冲激光在532 nm处检测了它在四氢呋喃溶液中的光限幅过程,发现该化合物具有非常明显的光限幅性能.在很低的入射光能量下,输出能量即开始偏离Beer定律,透过率随着入射光能量的增加迅速下降.这一效应归因于酞菁分子的反饱和吸收.通过纳秒激光闪光光解实验测定了上述化合物在四氢呋喃溶液中的瞬态吸收光谱及三线态寿命,实验结果表明在很宽的波长范围内分子具有较强的激发态吸收性能.     

酞菁铜分子的电子态和反饱和吸收

用ROHF-INDO/SDCI方法结合实验研究了酞菁铜分子的电子的电子结构.紫外-可见光谱.激发态分子动态学和反饱和吸收的微观机制.对酞菁铜实现反饱和吸收的必要条件是最低四重态对激光的吸收截面必须大于基态对激光的吸收截面. 在波长为532nm的激光作用下.该条件得到了满足,故Cupc呈现反饱和吸收特征.理论分析与实验结果一致.     

酞菁类光电材料研究新进展

酞菁类化合物具有优异的光电响应性能,是光电材料领域最活跃的研究方向之一.评述了酞菁类化合物近几年在不同领域的研究进展,分析总结了酞菁和取代基酞菁的分子结构、晶体形态对光伏材料、薄膜半导体材料、液晶材料、光导材料和电致发光材料等应用性能的影响以及目前存在的问题,最后对酞菁类光电材料的研究和发展前景进行了展望.     

有机金属酞菁类化合物及其非线性光限幅特性

随着激光技术的快速发展, 激光武器的性能也越来越优越, 所造成的危害也越来越大, 各国开始加大力度对激光防护材料进行研究. 酞菁化合物具有限幅窗口宽、限幅效果明显、响应迅速等特点, 是一类非常具有应用前景的光限幅材料. 当前, 制备出限幅性能好、稳定性强的酞菁光限幅材料成为激光防护材料领域中的研究热点. 本文评述和总结了近几年在酞菁光限幅材料方面开展的系统研究工作, 首先介绍了酞菁化合物实现光限幅效应的机制, 并在此基础上详细分析了影响光限幅效应的因素以及光限幅器件化过程对酞菁光物理和光限幅性能的影响机理. 根据分析结果提出了在基础和应用研究方面存在的科学问题, 指出了该类型光限幅材料面临的挑战和今后的重要发展方向.     

酞菁与TiO2微粒间的光诱导电子转移相互作用

带有负电荷取代基的四磺化酞菁化合物与TiO2超微粒在溶液中通过静电相互吸引,能够形成基态复合物。通过吸收光谱和荧光光谱,计算了磺化酞菁与TiO2在溶液中的表现缔合平衡常数K.与相应的烷氧基取代酞菁化合物作比较,并通过单光子技术测定染料荧光寿命。结合荧光光谱,证明了磺化酞菁与TiO2在溶液中的缔合作用,有利于激发态酞菁染料向半导体TiO2的导带注入电子,从而发生分子间的电子转移反应,将磺化酞菁吸附在TiO2纳晶薄膜电极上,进行光电性能测试。结果表明,染料敏化TiO2纳晶薄膜电极光电响应的大小与染料在电极表面吸附的强弱有关。     

酞菁与TiO2超微粒间的光诱导电子转移相互作用

带有负电荷取代基的四磺化酞菁化合物与 TiO2超微粒在溶液中通过静电相互吸引 ,能够形成基态复合物 .通过吸收光谱和荧光光谱 ,计算了磺化酞菁与 TiO2在溶液中的表观缔合平衡常数 K.与相应的烷氧基取代酞菁化合物作比较 ,并通过单光子计数技术测定染料荧光寿命 .结合荧光光谱 ,证明了磺化酞菁与 TiO2在溶液中的缔合作用 ,有利于激发态酞菁染料向半导体 TiO2的导带注入电子 ,从而发生分子间的电子转移反应 .将磺化酞菁吸附在 TiO2纳晶薄膜电极上 ,进行光电性能测试 .结果表明,染料敏化 TiO2纳晶薄膜电极光电响应的大小与染料在电极表面吸附的强弱有关 .     

高分子光伏材料聚对苯乙烯撑-喹喔啉共聚物的合成与光学性能研究

高分子光伏材料聚对苯撑乙烯撑(PPV)由于低廉的价格, 容易加工的性能与可调的光学性能, 有可能成为新一代太阳能材料. 然而PPV较宽的带隙阻碍了PPV太阳能电池效率进一步提高. 合成了一种较低带隙的新型高分子光伏材料 PPV-PQ. 用NMR, FT-IR, 元素分析, GPC和TGA与循环伏安法对PPV-PQ进行了结构表征与性能检测, 并对它在氯仿溶液与固态薄膜下的紫外-可见吸收与荧光发射光谱进行了研究. 结果显示, 由于在固态下存在较强的分子间作用, 分子链的共平面性增加, 所以PPV-PQ无论是紫外-可见吸收, 还是荧光发射光谱, 在固态薄膜下都比在氯仿溶液里发生明显红移. 即使在浓溶液中, 分子链间也存在较强的作用力, 使得PPV-PQ荧光发射峰随溶液浓度的增加而发生红移. 紫外-可见光谱显示, PPV-PQ由于大体积的吸电子单元引起了较大的空间位阻, 最大吸收峰比PPV稍微蓝移, 但吸收却比PPV向长波延展, 带隙比PPV低, 只有1.92 eV. 循环伏安法结果表明PPV-PQ与PCBM两者的LUMO之间有足够的能量差异, 加上PPV-PQ与富勒烯衍生物C117共混物薄膜发生荧光猝灭, 都说明PPV-PQ上光激发电子能够转移到富勒烯衍生物上. 因此, PPV-PQ可以用作高分子光伏材料.     

直流反应磁控溅射制备的Mo掺杂TiO2薄膜的光电特性

通过直流反应磁控溅射制备了不同Mo掺杂量的Mo-TiO2薄膜.用原子力显微镜(AFM)、X射线衍射(XRD)仪、X射线光电子能谱(XPS)仪、紫外-可见(UV-Vis)分光光度计详细研究了Mo掺杂量对薄膜表面形貌、晶体结构、元素价态及吸收带边的影响.用瞬态光电流和循环伏安法考察了不同Mo含量ITO/Mo-TiO2电极的光电特性.结果表明:在TiO2薄膜中掺入的Mo以Mo6+和Mo5+两种价态存在;随着Mo掺杂量的增加,Mo-TiO2薄膜的晶粒尺寸逐渐减小,晶格畸变增大,吸收阈值显著红移;薄膜的禁带宽度先减小后增大,在Mo掺杂量为2.7%(n(Mo)/n(Ti))时禁带宽度最小;Mo掺杂量为0.9%的样品在氙灯下的光生电流最大,且随着所加阳极偏压的提高光生电流并未呈现出饱和的趋势.此后随着掺杂量的提高,薄膜的光生电流开始下降,当Mo掺杂量达到3.6%时,薄膜的光电流小于未掺杂的样品;说明适当浓度的Mo掺杂能够提高Mo-TiO2薄膜光电性能,光生电流最大可达未掺杂的2.4倍.     

酞菁钴(Ⅱ)轴向配合物的合成及其光谱特性研究

本文合成了一种酞菁钴(Ⅱ)化合物,研究了它在溶液中与咪唑形成轴向配合物的吸收光谱变化,并计算了配合物的组成及稳定常数.用旋涂法制备了染料薄膜,通过配合物的吸收光谱与酞菁钴(Ⅱ)的比较,光谱峰显著变窄,吸收峰红移,大大改善了染料的光学性质.     

Nonlinear optical effects related to saturable and reverse saturable absorption by subphthalocyanines at 532 nm

It is found that both effects of saturable absorption and reverse saturable absorption are obtained with a solution of subphthalocyanine at 532 nm depending on the intensity of 9 ns laser pulses; saturable absorption occurs at lower intensity levels whereas the reverse effect prevails at higher levels; contrary to expectations, subphthalocyanines can behave as reverse saturable absorbers at 532 nm, despite the high linear absorption at this wavelength; data have been fitted with a five-level model which considers three consecutive electronic transitions with absorption cross-section values of 1.4 x 10(-16), 1.0 x 10(-16) and 40 x 10(-16) cm(2), respectively.     

Investigation of the excited-state absorption of a Ru dioxolene complex by the Z-scan technique

We investigated nonlinear absorption of picosecond laser pulses in a Ru complex [{Ru(bipy)2}2L][PF6] using the open-aperture Z-scan technique. Experiments were performed in a spectral region of moderate linear absorption (lambda=532 nm, sigmag=0.65 x 10(-16) cm(-2)). We observed a transition from reverse saturable absorption to saturable absorption when the excitation intensity was higher than 50 GW/cm2. To determine the population level kinetics, a model based on three- and four-level systems was considered, and the rate equations solved taking into account the propagation equation of the laser pulse inside the sample. Fitting of the experimental data allows extraction of the excited-states absorption cross sections and lifetimes.     

Resonant nonlinear absorption in Zn-phthalocyanines

In this work, we investigate the nonlinear absorption dynamics of Zn phthalocyanine in dimethyl sulfoxide (DMSO). We used single pulse and pulse train Z-scan techniques to determine the dynamics and absorption cross-sections of singlet and triplet states at 532 nm. The excited singlet state absorption cross-section was determined to be 3.2 times higher than the ground state one, giving rise to reverse saturable absorption. We also observed that reverse saturable absorption occurs from the triplet state, after its population by intersystem crossing, whose characteristic time was determined to be 8.9 ns. The triplet state absorption cross-section determined is 2.6 times higher than the ground state one. In addition, we used the white light continuum Z-scan to evaluate the singlet excited state spectrum from 450 to 710 nm. The results show two well-defined regions, one above 600 nm, where reverse saturable absorption is predominant. Below 600 nm, we detected a strong saturable absorption. A three-energy-level diagram was used to explain the experimental results, leading to the excited state absorption cross-section determination from 450 nm up to 710 nm.     

Indium phthalocyanines with different axial ligands: a study of the influence of the structure on the photophysics and optical limiting properties

The photophysical properties of four axially substituted indium phthalocyanines, namely, 2,(3)-tetra- tert-butyl-phthalocyaninato indium chloride ( 1), 2,(3)-tetra-[(3,5-di- tert-butyl)-phenyloxy]-phthalocyaninato indium bromide ( 2), 2,(3)-tetra-[(3,5-di- tert-butyl)-phenyloxy]-phthalocyaninato indium iodide ( 3), and 2,3-octa-[(2-hexyl)-ethyloxy]-phthalocyaninato indium trifluoroacetate ( 4), have been investigated, and their optical limiting properties with nanosecond light pulses were evaluated. All complexes behave as reverse saturable absorbers in the range of 400-625 nm due to a triplet-triplet excited-state transition. Excited-state absorption cross sections and triplet state lifetimes are not significantly affected by the nature of the axial ligand. On the other hand, remarkable differences in the variation of nonlinear transmittance are observed for 1- 4 due to significantly different intersystem crossing rates. Heavier axial ligands in phthalocyanines 2 and 3 produce the largest variations of nonlinear transmission (heavy-atom effect). Complex 1 in polystyrene matrix shows reversible nonlinear absorption when incident fluence does not exceed 0.025 J cm (-2).     

Syntheses, and optical, fluorescence, and nonlinear optical characterization of phosphine-substituted terthiophenes

Earlier studies of phosphine-substituted terthiophenes have demonstrated that some of these materials exhibit nonlinear absorption at 532 nm. However, this wavelength is significantly removed from the linear absorption maxima of the complexes, suggesting that better nonlinear absorption might be observed at wavelengths closer to the linear absorption maxima. To investigate this possibility, a library of compounds has been prepared either by varying the group attached to the nonbonding pair of electrons on the phosphorus atoms of 5,5'-bis(diphenylphosphino)-2,2':5',2'-terthiophene (PT(3)P), or by introducing additional substituents on the 5'-position of 5-(diphenylphosphino)-2,2':5',2'-terthiophene (PT(3)). All these compounds have been characterized using multinuclear NMR, UV-vis, and fluorescence spectroscopy. The compounds are strongly fluorescent, and both the fluorescence wavelength and the intensity depend upon the thiophene substituents. The nonlinear optical properties have also been evaluated at various wavelengths in the blue region. Each compound exhibits reverse saturable absorption, and the intensity of the reverse saturable absorption at a particular wavelength depends on the chemical structure of the compound.     

双波长叠加吸收光谱法测定药物中的酒石酸美托洛尔

建立了快速、准确测定药物中酒石酸美托洛尔的双波长叠加可见吸收光谱法。在pH 4.55的酸性Tris-盐酸介质及586~740 nm波长范围内,偶氮氯膦Ⅲ与酒石酸美托洛尔反应生成具有两个明显正吸收峰的离子缔合物,最大正吸收波长位于614 nm,次大正吸收波长位于664 nm,表观摩尔吸光系数(κ)分别为6.03×10~4L/(mol·cm)(614 nm)和5.37×10~4L/(mol·cm)(664 nm),酒石酸美托洛尔的质量浓度在0.2~8.6 mg/L范围内服从朗伯-比尔定律,检出限为0.13 mg/L(614 nm)和0.15 mg/L(664 nm)。当采用双波长叠加法测定时,其表观摩尔吸光系数(κ)可达1.14×10~5L/(mol·cm),检出限为0.072 mg/L。该文同时探讨了显色反应的适宜条件、共存物质的影响及吸收光谱特征。实验发现,该反应体系的单波长及双波长叠加吸收光谱法的表观摩尔吸光系数可达5.37×10~4~1.14×10~5L/(mol·cm),方法可用于市售药物中酒石酸美托洛尔含量的测定,加标回收率为98.0%~101%,相对标准偏差(n=6)为1.8%~2.3%。     

Nonlinear absorption dynamics in tetrapyridyl metalloporphyrins

Nonlinear absorption dynamics of Zn(2+), Cu(2+), and Ni(2+) tetrapyridyl porphyrins in chloroform/methanol solutions were investigated at 532 nm with the Z-scan technique. Additional techniques such as UV-vis absorption spectroscopy and time-resolved fluorescence were used to obtain parameters that are important for the analysis of the population dynamics. A marked difference was observed in the nonlinear absorption and excited-state dynamics of closed (ZnTPyP)- and open-shell metalloporphyrins (CuTPyP and NiTPyP). ZnTPyP presents a reverse saturable absorption whose dynamics can be completely described by means of a simple five-energy-level diagram. On the other hand, CuTPyP and NiTPyP have a different excited-state dynamics, presenting a saturable absorption behavior and faster relaxation rates that were attributed to the presence of unfilled d shells of the central ion.     

Spectroscopic study of laser-induced phase transition of gold nanoparticles on nanosecond time scales and longer

The pulsed laser induced phase transition of gold nanoparticles in aqueous solution was observed via a transient absorption on nanosecond time scales and longer. Gold nanoparticles were excited with an intense picosecond laser pulse (355 nm, 30 ps), and the subsequent changes were monitored using two continuous wave laser wavelengths (488 and 635 nm). On the nanosecond time scale, below 6.3 mJ cm(-2), no change was observed; however, in the low fluence region between 6.3 and 17 mJ cm(-2), gold nanoparticles produced a bleach signal (488 nm) attributed to the melting of the gold nanoparticles, which decreased linearly with increasing laser fluence. Laser fluences above 17 mJ cm(-2) resulted in a strong absorption at both wavelengths, which is ascribed to vaporization of gold nanoparticles rather than solvated electrons (ejected from gold nanoparticles) or light scattering. The decay of both signals was faster than the 5 ns time resolution used in our experimental system. On the microsecond time scale, increase in absorbance at 635 nm was observed with a time constant of 1.0 micros, while no change was observed at 488 nm. It is considered that this increase is attributed to the formation of smaller gold nanoparticles resulting from pulsed laser induced size reduction of initial gold nanoparticles.