苯并咪唑的三维荧光光谱与三维室温磷光光谱

测量了浓度为1×10^-4mol/L苯并咪唑水溶液的三维荧光光谱,三维室温磷光光谱和紫外/可见吸收光谱,还测量了苯并咪唑固体紫外/可见吸收光谱对化合物的荧光和室温磷光进行了分析、比较,发现苯并咪唑在290nm、580nm和870nm区域均有强而丰富的荧光谱线,而室温磷光谱线(RTP)单一地出现在290nm区域,且强度很小;同时还讨论了苯并咪唑的升频转换荧光现象.     

紫外波段有机染料DMT掺杂SiO2薄膜的光谱特性

本文采用溶胶凝胶法合成了紫外波段有机染料DMT掺杂SiO₂薄膜和块体材料薄膜中掺杂浓度高达124×10^-2mol/L,块体材料浓度掺至15×10^-3mol/L由于SiO₂“笼”的束缚作用,在荧光光谱中未观察到荧光猝灭现象;由于SiO₂“笼”的极化作用,370nm的发射峰较其在环己烷中发生了34～44nm左右的红移;580～590nm的发射峰的量子效率比370nm的发射峰略高.     

高光洁度玻璃基片的表面散射和体散射测量

 提出了一种利用总积分散射（TIS）测量K9玻璃基片表面散射和体散射的实验方法。首先采用磁控溅射技术在基片表面沉积厚度为几十nm的金属Ag薄膜，然后将基片的表面和体区分开考虑，通过TIS测得了基片上下表面的均方根粗糙度， 进而求得基片的总散射和表面散射，最后计算得到了体散射。分别利用TIS和原子力显微镜（AFM）测量了3个样品上表面所镀Ag膜的均方根粗糙度，两种方法所得的均方根粗糙度的数值相差不明显，差值分别为0.08，0.11和0.09 nm, 表明TIS和AFM的测量结果相一致。利用该方法测得3块K9玻璃基片的总散射分别为6.06×10^-4，5.84×10^-4和6.48×10^-4，表面散射介于1.25×10^-4~1.56×10^-4之间，由此计算得到的体散射分别为3.10×10^-4，3.30×10^-4和3.61×10^-4。     

HD+离子在两个超短脉冲激光场作用下的解离几率分布

本文报告HD⁺离子在波长λ=306.7nm的三倍频超短脉冲弱光场E₃和不同延时的二倍频超短脉冲强光场E₂作用下解离几率分布的定量计算结果。E₃和E₂的脉冲宽度均为10fs.E₃先行,E₂延时取0、4、8、12、16、20、24、28fs.计算结果用三维图表出。图中看到,沿相对动量坐标有三个峰,分别位于动量2.1×10^-18、4.4×10^-18、5.8×10^-18g·cm/s处,依次称为1号峰、2号峰、3号峰,位置各是λ=306.7nm的单光子能量、双光子能量、三光子能量消耗于解离能之后离子碎片具有相对动量。据分析,1号峰来源于E₂场引起的受激发射作用。     

流体静压力对InSb输运性质的影响

在室温和流体静压力达12500公斤/厘米²下,测量了不同掺杂浓度的n型(5×10¹³—2.3×10¹⁸厘米^-3和p型(2.6×10¹⁴—6.0×10¹⁷厘米^-3)InSb的霍耳系数和电导率。分析结果发现,霍耳系数公式中散射因子随压力而减小,禁带宽的压力系数不是常数;得出禁带宽、载流子浓度、电子和空穴迁移率与压力的关系,并对压力下的载流子散射机构作了初步讨论。     

强激光场中离子HD+光解离几率的相干控制

对含时薛定谔方程用短时传播子的对称分割法求得了非微扰的数值解,计算了强超短脉冲基频激光(波长306.7nm)与其三倍频激光作用下的离子HD⁺光解离的相干控制参量大小设该离子的初态为电子振动.基态其中的相干激发是共振的.二束光之间的相对相位变化从0到360°在基频和倍频激光强度各为5×10¹³W/cm²和5.09×10⁸W/cm²情形下,发现相对相位为π时,光解离几率达到最大。     

离子注入ZnO薄膜的拉曼光谱研究

室温下,用80 keV N⁺和400 keV Xe⁺离子注入ZnO薄膜,注入剂量分别为5.0×10¹⁴—1.0×10¹⁷/cm²和2.0×10¹⁴—5.0×10¹⁵/cm².利用拉曼散射技术对注入前后的ZnO薄膜进行光谱测量和分析,研究了样品的拉曼光谱随离子注入剂量的变化规律.实验结果发现,未进行离子注入的样品在99,435 cm<     

超短超强激光与薄膜靶作用的光学光谱

 在SILEX-Ⅰ超短超强激光装置上,研究了30 fs,1.0×10¹⁹ W/cm²超短超强激光脉冲与薄膜靶作用产生的发射光谱。对于3 μm厚的铜靶,在激光沿靶面的镜面反射方向观测到二倍频和3/2倍频光谱,且都发生了红移。由红移量推测出等离子体反射面的后退速度约为2.6×10⁸ cm/s。对于200 nm厚CH靶,沿激光传播方向观察到超连续光谱,光谱波长范围从约300 nm延伸至约940 nm。利用MULTI-1D流体程序,模拟了超强激光的预脉冲与薄膜靶相互作用过程,结果表明,预脉冲对预等离子体的密度分布有显著影响,是导致实验观测光谱差异的原因。     

CoFe2O4纳米粒子的共振散射光谱研究

液相纳米粒子CoFe2O4在400，470，510，800和940nm产生五个共振散射峰。它是一种非线性光散射介质。当激发波长为330nm时，CoFe2O4纳米粒子分别在于330，660和990nm产生一个共振散射峰、一个1/2频散射峰和一个1/3分频散射峰；当激发波长为800nm时，在800nm产生一个共振散射峰，而在400nm产生一个较该共振散射峰更强的2倍频散射峰。分频散射和倍频散射与共振散射有相似的散射行为。根据建立的灰白粒子体系共振散射光谱原理定性解析了CoFe2O4纳米粒子体系的共振散射光谱。     

1 053，527，351 nm倍频分离膜的制备与性能研究

 用电子束蒸发及光电极值监控技术在石英基底上沉积了三倍频分离膜，将部分样品置空气中于250 ℃温度下进行3 h热退火处理。然后用Lambda900分光光度计测量了样品的光谱性能；用表面热透镜技术测量了样品的弱吸收值；用调Q脉冲激光装置测试了样品分别在355 nm和1 064 nm的抗激光损伤阈值。实验结果发现，样品的实验光谱性能良好，退火前后其光谱性能几乎没有发生温漂，说明薄膜的温度稳定性好；同时弱吸收平均值从退火前的1.07×10^-4下降到退火后的6.2×10^-5，从而使对基频的抗激光损伤阈值提高，从14.6 J/cm²上升到18.8 J/cm²，但是三倍频阈值在退火后有显著降低，从7.5 J/cm²下降到2.5 J/cm²。     

兔红细胞的共振散射光谱研究

研究了液相兔血红细胞的共振散射光谱 (RSS)及非线性分频散射和倍频散射。兔红细胞浓度在0 0 15～ 31 1× 10 6个·(mL) -1范围与共振散射光强度成线性关系。对非线性散射机理进行了探讨。     

Small-angle neutron scattering study of the nano-sized features in an oxide dispersion-strengthened Fe12Cr alloy

Small-angle neutron scattering experiments, along with positron lifetime measurements and transmission electron microscopy observations, were performed on samples of an oxide dispersion-strengthened (ODS) Fe12Cr alloy and its non-ODS counterpart in order to characterize their nano-sized features. The nuclear and magnetic scattering data were analysed using the maximum entropy approach for obtaining the size distribution of the scattering centres in these materials. The positron annihilation results and the TEM information have made possible an interpretation of the volume distribution of the scattering centres having sizes below ~16 nm and their proper quantitative analyses. The smaller scattering centres in the ODS alloy exhibit distributions with modal values at ~6–7 and 12–14 nm. The peak at ~6–7 nm appears to be due to the overlapping of more than one type of scattering centres, while the one at ~12–14 nm can be exclusively attributed to the Y-rich centres. The quantitative analysis of the magnetic scattering data yields a volume fraction and number density of the Y-rich particles estimated in 0.70?±?0.03% and 0.77 × 10²² m^?3, respectively.     

Optical pump - nuclear resonance probe experiments on spin crossover complexes

A novel sample environment enabling optical pump – nuclear resonance probe experiments has been installed at the beamline P01, Petra III, DESY Hamburg. This set-up has been used to investigate optically induced spin state changes of spin crossover (SCO) complexes by nuclear resonant scattering immediately after excitation by an optical laser pulse. Here, we report the technical details as well as first results of the experiments performed at 290 K and 80 K on the SCO complexes [Fe (NH₂trz)₃]Cl₂ and [Fe(PM-BiA)₂(NCS)₂], respectively. The ⁵⁷Fe-enriched SCO complexes were excited by a 531 nm laser with a pulse length <?100 ps. Evaluation of the nuclear forward scattering data clearly indicate the presence of high spin (HS) states when the complexes are excited by laser pulses and a pure low spin (LS) state in the absence of any laser pulse. Furthermore, the dependence of the optically excited HS-fraction has been determined as a function of the average optical power.     

A high-resolution Ramsey-Bordé spectrometer for optical clocks based on cold Mg atoms

We report on recent progress in our Ramsey-Bordé interferometer with cold magnesium atoms at 457.2 nm. A resolution as high as was achieved, which corresponds to a quality factor of Q = 2.3×10¹². An upper limit of 170 Hz for the laser oscillator line width is inferred from the interferometric analysis of the contrast decay induced by the residual atomic motion and spontaneous emission. The performance of the spectrometer allows to realize an optical frequency standard at 457.2 nm with a short-term stability of up to with 10⁵ atoms similar to state-of-the art, non-cryogenic microwave clocks or oscillators.     

Superior tolerance of Ag/Ni multilayers against Kr ion irradiation: an in situ study

Monolithic Ag and Ni films and Ag/Ni multilayers with individual layer thickness of 5 and 50?nm were subjected to in situ Kr ion irradiation at room temperature to 1 displacement-per-atom (a fluence of 2?×?10¹⁴?ions/cm²). Monolithic Ag has high density of small loops (4?nm in diameter), whereas Ni has fewer but much greater loops (exceeding 20?nm). In comparison, dislocation loops, ～4?nm in diameter, were the major defects in the irradiated Ag/Ni 50?nm film, while the loops were barely observed in the Ag/Ni 5?nm film. At 0.2?dpa (0.4?×?10¹⁴?ions/cm), defect density in both monolithic Ag and Ni saturated at 1.6 and 0.2?×?10²³/m³, compared with 0.8?×?10²³/m³ in Ag/Ni 50?nm multilayer at a saturation fluence of ～1?dpa (2?×?10¹⁴?ions/cm²). Direct observations of frequent loop absorption by layer interfaces suggest that these interfaces are efficient defect sinks. Ag/Ni 5?nm multilayer showed a superior morphological stability against radiation compared to Ag/Ni 50?nm film.     

Improved absolute frequency measurement of the 115In+ 5s2 1S0-5s5p3P0 narrowline transition: Progress towards an optical frequency standard

We report on an improved absolute frequency measurement of the 5s ^{2 1} S ₀0-5s5p ³ P ₀ narrowline clock transition at 236.5 nm, for a single, trapped, and laser-cooled ¹¹⁵In ion. Using a narrowline laser as the local oscillator, a linewidth of 43 Hz for the transition is resolved. The uncertainty of the transition frequency’s centroid is 18 Hz, leading to a fractional uncertainty of 1.4 × 10⁻¹⁴. For absolute frequency measurement, we use an optical frequency comb locked to a cesium clock as the reference. The transition frequency is found to be 1267402452900967(63) Hz, averaged over 13 days of separate measurements. The accuracy is about 5.0 × 10⁻¹⁴. We discuss possibilities for further improvement. Original Text ? Astro, Ltd., 2007.     

Characterization of high purity GaAs far-infrared photoconductors

In this paper we report the results of an extensive study on the far-infrared photoconductivity of high purityn-type GaAs. The crystal, which was grown at Max-Plank-Institute for Solid State Physics using liquid-phase epitaxy, exhibited the fine structures of the excited state transitions of the residual shallow level impurities. The major peak in the spectral response belongs to the 1s-2p transition, with its responsivity about thirty five times higher than the continuum. At 3.4K detector temperature, 625 mV bias, and 100 Hz chopping frequency the detector responsivity at 35.4 cm^–1 (279 µm) was measured to be 0.017 A/W. Under these same conditions, the NEP was 5.9×10^–14 W/Hz. The (DC) dark current at 25 mV bias was 5.6×10^–14 A.     

Sum frequency generation at 309 nm using a violet and a near-IR DFB diode laser for detection of OH

We have used a violet diode laser at 404 nm and a distributed feedback diode laser at 1320 nm to produce 0.8 nW of radiation at 309 nm by sum frequency generation in beta-barium borate. The UV radiation was tuned mode-hop-free over 30 GHz and used to detect OH radicals produced in a microwave discharge. By chopping the UV light at 500 Hz, we observed a concentration of 2×10¹² cm^-3 with a signal to noise ratio of 30:1. Received: 16 November 2001 / Revised version: 23 January 2002 / Published online: 14 March 2002