n型6H-SiC拉曼散射光谱的温度特性（英文）

三片具有不同载流子浓度的n型6H-SiC体材料用于83K到673K的变温拉曼散射研究,能够得到变温的拉曼散射模。通过测量可以得到,随着温度的增长,不同的声子散射模的拉曼峰逐渐变小。运用声子频率的温度特性计算公式,对三片样品的三个声子模的峰位进行拟合能够得到很好的拟合结果。6H-SiC样品的纵光学声子模(LOPC)的拉曼位移像其他的拉曼模一样,随着温度的增加而变小。在较高的温度时所有的声子模明显展宽。     

6H-SiC的A_1(LO)拉曼峰低温温度特性研究

对6H-SiC单品体材料进行了从80到320 K的低温变温拉曼光谱测量,从实验得到的谱图上指认了部分6H-SiC的折叠拉曼峰,重点利用三声子模型和四声子模型分析了A1(LO)光学声子模峰位和线宽在低温下随温度的变化特性.实验发现,随着温度降低,LO声子模谱峰中心向高波数移动,线宽减小;同时发现当温度低于160 K时,无论足谱峰中心位置还是线宽的变化都趋于平缓,这是在常温和高温下观察不到的,说明在160 K以下时A1(LO)谱线线宽是由声子本身的性质决定,温度对线宽的影响几乎可忽略;理论拟合表明,四声子模型更能与实验数据相符,三次、四次非谐振动共同作用,前者是主要过程;温度越低,A1(LO)光学声子寿命越长,这是由于原子热运动的剧烈程度随温度降低而下降,声子弛豫减弱.     

稻瘟病、玉米锈病和蚕豆锈病叶的傅里叶变换红外光谱研究

利用傅里叶变换红外光谱(FTIR)研究了水稻、玉米、蚕豆正常叶和稻瘟病叶、玉米和蚕豆锈病叶。结果显示,其红外光谱均主要由多糖、蛋白质的振动吸收谱带组成。光谱整体相似,差异主要表现为光谱峰位、峰形及吸收强度比。三种作物正常叶的二阶导数光谱在1 750～1 500 cm-1范围内的相关系数差异明显。水稻正常叶与稻瘟病叶的吸收强度比A_{1 056}/A_{1 652};蚕豆正常叶与锈病叶的吸收强度比A_{1 652}/A_{2 920};玉米正常叶和锈病叶(非病斑部位)吸收强度比A_{1 056}/A_{2 920},玉米正常叶和玉米锈病叶(病斑处)吸收强度比A_{1 652}/A_{2 920},均呈现出病变叶吸收强度比正常叶要小的趋势。表明他们之间的多糖和蛋白质的含量存在差异。     

高纯汽相生长GaP的场致发光及电学性质

研究了以汽相外延法在整片单晶GaP衬底上生长的高纯GaP的场致发光、霍尔系数、电阻率同温度的关系。在77°K和300°K分别获得高达2370厘米~2/伏秒和189厘米~2/伏秒的霍尔迁移率。以Zn 扩散制成的二极管的场致发光表现为本征复合。在77°K时,除了由于在中性施主位置上的束缚激子复合而引起的狭的非声子谱线外,近边带场致发光还呈现出一组界线分明的谱峰,相应于自由激子的声子协助的复合(下文中简称为“声协”复合)。这些观察到的峰,既和 TA、LA、TO声子的吸收有关,也和它们的发射有关;它们的能量分别为12.5,31.0,44.0毫电子伏。和声子发射有关的谱峰强度对于TO、LA和TA声子来说,大概比率是1:3:1.5。这些能量和相对强度是和本征GaP的吸收及阴极射线发光数据一致。在氮和别的任意杂质浓度很低的器件中,场致发光和温度的关系表明:300°K的发射以本征复合占优势。     

pH值对秸秆腐殖化溶解性有机质紫外光谱和荧光光谱的影响

秸秆是农业生产的主要副产物,也是农业面源污染的新源头。秸秆还田能有效解决其减量化和资源化利用问题,国家“十二五”规划已明确提出“加大秸秆还田力度,保障农业的稳产、增产和可持续发展”。现阶段,对于典型地区不同环境条件下还田秸秆腐殖化行为的研究不多,同时对于腐殖化组分的精细化检测和分析也有待加强。针对黄土区秸秆还田问题,以紫外光谱法和荧光光谱法为切入点,分析pH值对腐殖化产物溶解性有机质(Dissolved organic matter, DOM) 性质的影响,深度揭示秸秆腐殖化过程的内在本质。结果表明：在200～700 nm波长范围内,DOM的紫外吸收强度先增加后减小,主要吸收峰出现于240 nm附近。相对于中性(pH 7)体系,酸性(pH 6)和碱性 (pH 8和9) 条件下的最大吸收波长λ_max值红移。SUVA₂₅₄,E₃/E₄和A₂₅₃/A₂₀₃比值的规律性变化说明反应体系腐殖化程度较低,这与秸秆腐殖化周期较短有关。黄土浸提液DOM的荧光峰主要位于λ_ex/em=250/330和λ_ex/em=325/450区域,分别归属为紫外区类富里酸荧光峰和可见光区类富里酸和腐殖酸类物质荧光峰。随着腐殖化体系pH值的升高,荧光峰位发生红移,表明DOM苯环结构逐渐增多,共轭度有所增加,同时在λ_ex/em=250/450附近检测到新荧光峰。pH值对荧光强度的影响主要体现在紫外区类富里酸荧光峰,峰强先升高后下降,而对可见光区荧光峰强影响不大,这与浸提液的缓冲效应、荧光猝灭(或副反应)和DOM组分结构有关。紫外光谱和荧光光谱能够一定程度上阐释pH值对秸秆腐殖化DOM性质的影响。     

InGaN合金中LO声子-等离子激元耦合模的研究

分别采用532,488 nm可见光和325 nm紫外光激发,对金属有机化学气相沉积法在蓝宝石衬底上生长的六方相InGaN/GaN薄膜样品在室温和78 K低温下的拉曼散射谱进行了研究。在可见光激发时,E₂模和A₁(LO)模的散射信号主要来自GaN层;采用紫外光激发时,A₁(LO)模向低频方向移动且共振增强,此散射信号来自InGaN层。在可见光激发的情况下,在A₁(LO)模的高频方向观察到一个宽峰,此宽峰为InGaN的LO声子-等离子激元耦合模,根据耦合模频率得到InGaN层中的电子浓度为n_ｅ＝1.61×1018 cm-3。紫外光激发时,没有观察到耦合模,A₁(LO)模散射信号主要来自样品表面耗尽层,由此估算样品中的耗尽层宽度大约在40 nm。此外,还对比分析了在室温和78 K低温下LO声子-等离子激元耦合模的散射强度的变化规律,计算了不同温度下等离子激元的屏蔽波矢。这些结论对于了解InGaN材料的基本性质以及氮化物光电器件的开发利用都有重要参考价值。     

镜泊湖水体水溶性有机物荧光特性研究

通过黑龙江省区域镜泊湖水体6个点位样品采集(样品号J1-J6),利用荧光检测技术,结合三维荧光光谱区域积分(FIR),研究了水溶性有机物(DOM)的荧光特性。传统荧光光谱显示J4和J5 DOM分子缩合度较高;三维荧光光谱显示J6点位DOM中类蛋白特征峰最为显著;对所有点位DOM的三维荧光光谱5个区域积分(A_Ⅰ,A_Ⅱ,A_Ⅳ：类蛋白区域;A_Ⅲ：类富里酸区域：A_Ⅴ：类胡敏酸区域)显示：所有点位DOM区域积分中A_Ⅴ区域占有比例最大,并且以J4和J5点位最高,J6点位最低。通过对腐殖酸区域(A_Ⅲ和A_Ⅴ积分比例之和)与类蛋白区域(A_Ⅰ,A_Ⅱ,A_Ⅳ积分比例之和)积分比值表明,J4(4.94)和J5(5.18)点位比值相近;J1(3.52)和J2(3.66)点位比值接近;最小值为J6点位(2.11)。综合以上分析证实,镜泊湖水体各点位DOM腐殖化程度为：J4,J5>J1,J2>J3>J6点位。     

氮化铝结构的高温Raman光谱分析

本文测量了氮化铝在不同温度下的Raman光谱 ,并确定了氮化铝的光学声子模E2 1、A1(TO)、E2 2 、E1(TO)、A1(LO)和E1(LO)Raman散射峰的频率 ,它们分别为 2 5 2cm- 1、6 1 4cm- 1、6 5 8cm- 1、6 72cm- 1、894cm- 1和 91 2cm- 1,其中光学声子模A1(TO)、E2 2 的Raman散射峰比较明显。随着温度的升高 ,A1(TO)、E2 2 散射峰的频率向低波数方向变化 ,表明氮化铝粉末压制体中存在的压应力逐渐减小 ;这两个散射峰的半高宽逐渐增大 ,说明随着温度的升高 ,存在氮原子和铝原子的扩散使得氮化铝粉末压制体中晶体结构逐渐发生变化。由于氮化铝粉末本身在空气中易与水蒸气发生反应 ,生成的Al(OH) 3 或AlOOH在加热过程会发生分解 ,干扰样品高温Raman光谱测量。     

0.5PZN-0.5PZT压电陶瓷拉曼散射研究

PZT基多元系压电陶瓷在三方相含量与四方相含量相等的准同型相界处(MPB)具有极为优异的压电性能。文章采用拉曼散射方法研究了0.5PZN-0.5PZT陶瓷体系中三方-四方相共存与弥散相变现象。研究发现,与纯PZT相比,0.5PZN-0.5PZT体系拉曼谱呈明显宽化特征,表明体系弛豫性较强,依据介温谱计算出弥散因子γ高达1.71。通过对拉曼谱峰进行Gauss函数拟合,定量计算三方相R₁模式与四方相E(3TO)和A₁(3TO)模式相对强度,以及四方相E(4LO)和A₁(3LO)模式与三方相R_h模式相对强度,结果表明0.5PZN-0.5PZT体系三方相与四方相含量相等,组成位于准同型相界,该结果得到XRD相分析验证。电学测量表明0.5PZN-0.5PZT陶瓷压电性能优异：k_p=0.66, d₃₃=425 pC/N,适宜作为压电致动器材料使用。     

镶嵌在SiO2薄膜中纳米GaAs颗粒的Raman散射研究

纳米GaAs颗粒通过射频磁控共溅法成功地被镶嵌在SiO_2薄膜中.通过不同基片温度下沉积的薄膜的Raman光谱观察到了明显的声子限域效应.其结果表明:当沉积时基片温度低于200℃时,X射线衍射和Raman散射均表现出非晶结构特征;当基片温度升高到300℃时,薄膜内的GaAs具有闪锌矿结构,同时其结构振动纵光学声子模对应的Raman散射峰将从非晶散射峰中分离出来,但同大块材料相比,该峰表现出明显的宽化和红移;随着沉积时的基片温度进一步提高,其宽化和红移相应地减小. 关键词：     

n-SiC拉曼散射光谱的温度特性

测量了采用离子注入法得到掺N的n-SiC晶体从100—450 K的拉曼光谱. 研究了SiC一级拉曼谱、电子拉曼散射谱及二级拉曼谱的温度效应. 实验结果表明,大部分SiC一级拉曼峰会随温度升高向低波数方向移动,但声学模红移(峰值位置向低频方向移动)的幅度较光学模小. 重掺杂4H-SiC的纵光学声子等离子体激元耦合(LOPC)模频率随温度升高表现出先蓝移(峰值位置向高频方向移动)后红移的变化趋势,表明LOPC模的温度特性不仅会受到非简谐效应的影响,还与实际已离化杂质浓度有关. 电子拉曼散射峰线宽随温度升高而增 关键词： 碳化硅 温度 纵光学声子等离子体激元耦合模 电子拉曼散射     

一种基于荧光材料的聚合物白光发光二极管

制备了一种基于荧光聚合物共混的单发光层聚合物白光发光二极管.器件结构为铟锡氧化物/苯磺酸掺杂聚乙烯基二氧噻吩/发光层/ 1,3,5-三(N-苯基-2-苯并咪唑-2)苯41/Ba/Al,蓝光材料芴-氟化喹喔啉共聚物(PF-BPFQ5)、绿光材料苯基取代的聚对苯乙炔(P-PPV)和红光材料聚(2-甲氧基-5-(2′-乙基己氧基)-1,4-对苯乙炔)(MEH-PPV)共混为发光层.当PF-BPFQ5,P-PPV,MEH-PPV的质量比例为100∶06∶06时,获得标准的白光,色坐标为（033 关键词： 聚合物发光二极管 白光 共混     

Dual Space Analyzing Based on Symmetry Properties for Phonons fo Si Quantum Dot

Phonon modes in spherical Si quantum dots (QDs) with up to 7.9 nm in diameter are calculated by using the projection operators of the group theory into valence force field model. The phonons of dot modes in each of five irreducible representations (symmetries) are classified by using a dual space analysis method. It is found that the bulk-like modes with localization radius much smaller than the dot's radius have clearly pronounced bulk specific-k point parentage, T_λ(n, k_BZ, K_cut), from specific part of the Brillouin zone (BZ) (Γ-derived, X-derived etc.) and from definite bulk band (one in six modes). In Si dots of all sizes, each specific bulk-like dot mode has specific symmetry. The bulk TO(Γ)-like and the bulk LO(Γ)-like dot modes always have T₂ and A₁ symmetries, respectively. Except the bulk-A(Γ)-like dot modes of which the frequencies blue-shift as the dot size reducing, the bulk-like Γ-derived LO and TO dot modes and bulk-like X-derived TA and LA dot modes red-shift in frequency with decreasing dot size. There is almost not LO/TO mixing for bulk-like modes. As for the surface-like modes localized at the periphery of the dot, their eigenmodes have not a dominant bulk specific-k point parentage or a dominant BZ parentage around some special point. They are a superposition of many bulk bands with k from all over the bulk BZ. They have much significant mode mixing than the bulk-like phonons. The classification of dot modes based on the symmetry of group theory will bring advantageous to the discussion of Ramam spectrum, electron-phonon interaction and other phonon-assisted effects in QDs.     

Dual Space Analyzing Based on Symmetry Properties for Phonons of Si Quantum Dot

Phonon modes in spherical Si quantum dots (QDs) with up to 7.9 nm in diameter are calculated by using the projection operators of the group theory into valence force field model. The phonons of dot modes in each of five irreducible representations (symmetries) are classified by using a dual space analysis method. It is found that the bulk-like modes with localization radius much smaller than the dot‘s radius have clearly pronounced bulk specific-κdefinite bulk band (one in six modes). In Si dots of all sizes, each specific bulk-like dot mode has specific symmetry.TO dot modes and bulk-like X-derived TA and LA dot modes red-shift in frequency with decreasing dot size. There is almost not LO/TO mixing for bulk-like modes. As for the surface-like modes localized at the periphery of the dot,their eigenmodes have not a dominant bulk specific-κ point parentage or a dominant BZ parentage around some special point. They are a superposition of many bulk bands with κ from all over the bulk BZ. They have much significant mode mixing than the bulk-like phonons. The classification of dot modes based on the symmetry of group theory will bring advantageous to the discussion of Ramam spectrum, electron-phonon interaction and other phonon-assisted effects in QDs.     

不同物料堆肥腐熟程度的紫外-可见光谱特性表征

水溶性有机物(DOM)紫外-可见吸收光谱特性是评价堆肥腐熟度重要方法之一,但由于紫外-可见吸收光谱指标众多,单指标评价具有较大局限性。因此,本研究开展了影响堆肥腐熟度的关键紫外-可见光谱特性指标识别,并采用化学剂量学方法评价了不同来源堆肥腐熟程度。与传统单一物料评价相比,优选的评价指标及评价方法更具普适性。不同物料堆肥过程中DOM紫外-可见光谱特性分析结果表明,SUVA₂₅₄和SUVA₂₈₀值呈明显的增加趋势,E₂₅₀/E₃₆₅和E₄/E₆值呈相反的趋势,而A_226～400,S_275～295,S_350～400值则在堆肥末期变化显著。相关分析表明不同紫外-可见光谱参数(E₂/E₄和E₂₃₅/E₂₀₃除外)彼此之间相关性显著;主成分分析显示,DOM紫外-可见光谱指标A_226～400, SUVA₂₅₄, S_350～400, SUVA₂₈₀, S_275～295可作为堆肥腐熟程度关键影响评价指标。在此基础上,采用筛选的特性指标对堆肥末期进行聚类分析,可将九种不同来源堆肥分为两大类,第一类为猪粪、鸡粪、污泥、秸秆、园林垃圾、果蔬及生活垃圾等腐熟程度较低的堆肥;第二类为杂草和厨余腐熟程度较高的堆肥。     

Resonance Raman study of He+ ion implanted nanostructured ZnS

ZnS nanocrytsals of size ∼2.5 nm were prepared by chemical precipitation technique. Pressed pellets of nanostructured ZnS were implanted with He⁺ ions at doses of 5 × 10¹⁴, 1 × 10¹⁵ and 5 × 10¹⁵ ions/cm². Raman spectra of both unimplanted and He⁺ ion implanted samples were recorded with ultraviolet (UV) excitation. LO, 2LO, 2TO, (LO + TA) and (2TO − TA) modes of ZnS were observed in the resonance Raman spectra of the unimplanted nanostructured ZnS samples. In addition, a surface mode was observed at 294 cm⁻¹. With the implantation of He⁺ ions, the 2TO mode disappeared and 2LO mode became prominent and this observation was attributed to the decrease in band gap of ZnS nanocrytsals due to ion implantation. The exciton–LO phonon coupling strength was determined from the intensity ratio of 2LO to LO modes and it was observed that the exciton–LO phonon coupling strength increases with increase in implantation dose. In the present work, we report for the first time the observation of 2TO mode in the resonance Raman spectrum of nanostructured ZnS and also the modification of exciton–LO phonon coupling strength of semiconductor nanoparticles by ion implantation. Copyright © 2008 John Wiley & Sons, Ltd.     

双层介电系统的Raman散射——ZnSe/玻璃和ZnSe/GaAs的表面声子模

本文实验观测了双层介电系统ZnSe/玻璃和ZnSe/GaAs的表面声子模,并利用极化场边界条件对上述体系的表面声子频率进行了计算。实验结果与计算结果符合得比较满意。     

Phonon Dispersion and Thermodynamics Properties of CaF2 via Shell Model Molecular Dynamics Simulations

The phonon and thermodynamics properties of face-centered cubic CaF2 at high pressure and high temperature are investigated by using the shell model interatomic pair potential within General Utility Lattice Program （GULP）. The phonon dispersion curves and the corresponding density of state （PDOS） in this work are consistent with the experimental data and other theoretical results. The transverse optical （TO） and longitudinal optical （LO） mode splitting as well as heat capacity at constant volume Cv and entropy S versus pressure and temperature are also obtained.     

Dependence of the excitation wavelength on the Raman-active phonons of YBa2Cu3O7 Search for Landau damping in single-domain crystals

In single-domain crystals of YBa₂Cu₃O₇, we examine the dependence of phonon linewidth on wavevector by varying the wavelength of the exciting laser. In three crystals, we find the linewidths of the Raman-active phonons at 120 and 150 cm⁻¹ to be nearly invariant for excitation wavelengths between 647 and 413 nm. That is, we find no broadening of the phonon linewidths with increasing phonon wavevector (decreasing excitation wavelength), and thus no evidence of Landau damping in our crystals. In addition, the correlation between the intensity of the chain-related Raman feature at ≈232 cm⁻¹ and the temperature dependence of the B_1g-like phonon at 340 cm⁻¹ has been investigated. In all three crystals, we find a net sharpening of the 340 cm⁻¹ phonon below T_c and essentially no intensity for the ≈232 cm⁻¹ mode under resonance conditions.     

海洛因的傅里叶红外吸收谱

给出海洛因和鸦片的傅里叶红外吸收实测谱。根据吸收峰的位置，计算出海洛因的基本声子能量：ＥＬＯ＝０．０４８６ｅＶ，ＥＴＯ１＝０．０５５５ｅＶ，ＥＴＯ２＝０．０６１６ｅＶ，ＥＬＡ＝０．０２５７ｅＶ，ＥＴＡ１＝０．００９７ｅＶ，ＥＴＡ２＝０．０１３４ｅＶ。这些声子按照不同的组合方式，形成海洛因的全部傅里叶红外吸收峰。