Photoluminescence study of InxGa1-xAs/InyAl1-yAs one-side-modulation-doped asymmetric step quantum wells

Fourier transform photoluminescence measurements were carried out to investigate the optical transitions in InxGa1-xAs/InyAl1-yAs one-side-modulation-doped asymmetric step quantum wells. Samples with electron density n(s) between 0.8 and 5.3 x 10(12) cm(-2) rue studied. Strong recombination involving one to three populated electron subbands with the first heavy-hole subband is observed. Fermi edge singularity (FES) clearly can be observed for some samples. The electron subband energies in the InGaAs/InAlAs step quantum wells were calculated by a self-consistent method, taking into account strain and nonparabolicity effects and the comparison with the experimental data shows a good agreement. Our results can help improve understanding for the application of InGaAs/InAlAs step quantum wells in microelectronic and optoelectronic devices. (C) 1998 Elsevier Science Ltd. All rights reserved.

The influence of substrate nucleation on HVPE-grown GaN thick films - art. no. 684105

Thick GaN films were grown on sapphire in a home-made vertical HVPE reactor. Effect of nucleation treatments on the properties of GaN films was investigated, including the nitridation of sapphire, low temperature GaN buffer and MOCVD-template. Various material characterization techniques, including AFM, SEM, XRD, CL and PL have been used to assess these GaN epitaxial films. It was found that the surface of sapphire after high temperature nitridation was flat and showed high density nucleation centers. In addition, smooth Ga-polarity surface of epitaxial layer can be obtained on the nitridation sapphire placed in air for several days due to polarity inversion. This may be caused by the atoms re-arrangement because of oxidation. The roughness of N-polarity film was caused by the huge inverted taper domains, which can penetrate up to the surface. The low temperature GaN buffer gown at 650 degrees C is favorable for subsequent epitaxial film, which had narrow FWHM of 307 arcsec. The epitaxial growth on MOCVD-template directly came into quasi-2D growth mode due to enough nucleation centers, and high quality GaN films were acquired with the values of the FWHM of 141 arcsec for (002) reflections. After etching in boiled KOH, that the total etch-pit density was only 5 x 106 cm(-2) illustrated high quality of the thick film on template. The photoluminescence spectrum of GaN film on the MOCVD-template showed the narrowest line-width of the band edge emission in comparison with other two growth modes.

Raman scattering study of vibrational modes and hole concentration in GaxMn1-xSb

The Raman scattering study of vibrational modes and hole concentration in a ferromagnetic semiconductor Ga1-xMnxSb grown by Mn ion implantation, deposition and post-annealing has been presented. The experiments are performed both in implanted and unimplanted regions before and after etching the samples. The Raman spectra measured from the unimplanted region show only GaSb-like phonon modes. On the other hand, the spectra measured from the implanted region show additional phonon modes approximately at 115, 152, 269, 437 and 659 cm(-1). The experimental results demonstrate that the extra modes are associated with surface defects, crystal disorder and blackish layer that is formed due to Mn ion implantation, deposition and annealing processes. Furthermore, we have determined the hole concentration as a function of laser probing position by modeling the Raman spectra using coupled mode theory. The contributions of GaSb-like phonon modes and coupled LO-phonon plasmon mode are taken into consideration in the model. The hole-concentration-dependent CLOPM is resolved in the spectra measured from the implanted and nearby implanted regions. The hole concentrations determined by Raman scattering are found to be in good agreement with those measured by the electrochemical capacitance-voltage technique.

I：端羟基液体聚丁二烯的氯化 II：氯化端羟基液体聚丁二烯的固化

合成了一系列氯含量不同的氯化丁羟（氯含量为5％～68％）。利用红外光谱、核磁共振观察了氯含量不同的氯化丁羟的双键变化。通过氯含量－5反应时间的关系及上述观察结果表明；丁羟在四氯化碳中进行氯化，首先进行加成反应，待双键饱和后，进行取代反应。用红外光谱观察了丁羟在氯化反应中三种微观结构的变化，观察了氯化高顺式聚丁二烯的双键变化，对氯化丁羟的赤苏异构体的碳－氯键红外光密度比值，进行了分析。这些观察和分析说明；丁羟在四氯化碳中氯化，存在着顺－反异构化反应。较详细地研究了影响交联反应的主要因素，利用低聚物的特点，通过数均分子量和粘度表征了交联反应程度。从而观察到，交联反应伴随着氯化反应之中，交联程度随着反应液中羟浓度的提高，随着反应时间的延长而增大。在一定反应液浓度下交联程度可以减小到很低程度，得到完全可溶的氯化丁羟。反应温度对交联反应在20～76℃范围无显著影响。提出了以氯乙醇为调节剂合成液体氯化丁羟的方法。实验结果说明，氯乙醇比文献中得到的乙醇在抑制交联反应，提高氯含量方面效果更好。氯化丁羟的羟值分析结果表明，丁羟的羟值在氯化反应中没有损失。这对氯化丁羟作为遥瓜型低聚物应用，在进行固化反应时，是非常重要的。随着溶剂介电常数的提高，出现凝胶的极限浓度也提高。根据这一实验和上述各项实验结果，基于烯类化合物氯化反应的一些基础研究工作。我们认为，在丁羟的氯化反应中，存在着两种反应机理；离子机理的加成，导致可溶氯化产物，自由基机理除加成外，导致交联，顺－反异构化反应。II 氯化丁羟与TDI的反应为二级反应。DBTDL（二月桂酸二丁基锡）对本固化反应有明显的催化效果。在100 ℃，以DBTDL为催化剂的固化反应中，氯化丁羟与TDI的反应速度常数为11.9 * 10~(-3)（升／克分子·秒），这个反应活化能为5.5千卡／克分子。合成了一系列的氯化丁羟聚氨酯。红外光谱测试结果表明，NH基分为两个红外吸收峰；3440 cm~(-1), 3310 cm~(-1)。高波频峰的为游离的NH基，低波频峰为缔合的NH基，其缔合度为88％。同时，表征了氯化丁羟聚氨酯的主要红外光谱吸收峰。研究了氯化丁羟聚氨酯的形态结构。透射电子微显镜示出氯化丁羟聚氨酯的微相分离区域结构，其硬段区域结构的尺寸大约趋于在0.7～1.6μ范围内（硬段含量30％）。差热分析和示差扫描量热分析结果一致表明，氯化丁羟聚氨酯在60 ℃-90 ℃范围内有一宽而弱的吸热转变区，在115 ℃左右有一吸热峰，它们归因于硬段区域结构的热转变。宽角X光衍射实验没有观察到明显的结晶吸收峰的存在。这个实验结果主要与氯化丁羟聚氨酯的无规、侧基及不对称的结构特点有关。初步实验结果显示出，氯化丁羟聚氨酯具有优异的粘结性能，其抗剪强度约是丁羟聚氨酯的六倍。通过氧化锌的作用，可以提高氯化丁羟聚氨酯的抗张强度。因为粘结强度是水轮机耐磨耐汽蚀涂层研制中比较关键的因素，所以，这个实验结果是很有意义的。

Kinetics of dissociative water adsorption on stepped Si(001), on Si(115), Si(113), Si(5,5,12) and Si(112)

We present photoelectron spectroscopic and low energy electron diffraction measurements of water adsorption on flat Si samples of the orientations (001), (115), (113), (5,5,12) and (112) as well as on curved samples covering continuously the ranges (001)-(117) and (113)-(5,5,12)-(112). On all orientations, water adsorption is dissociative (OH and H) and non-destructive. On Si(001) the sticking coefficient S and the saturation coverage Theta(sat) are largest. On Si(001) and for small miscuts in the [110]-azimuth, S is constant nearly up to saturation which proves that the kinetics involves a weakly bound mobile precursor state. For (001)-vicinals with high miscut angles (9-13 degrees), the step structure breaks down, the precursor mobility is affected and the adsorption kinetics changed. On (115), (113), (5,5,12) and (112), the values of S and Theta(sat) are smaller which indicates that not all sites are able to dissociate and bind water. For (113) the shape of the adsorption curves Theta versus exposure shows the existence of two adsorption processes, one with mobile precursor kinetics and one with Langmuir-like kinetics. On (5,5,12), two processes with mobile precursor kinetics are observed which are ascribed to adsorption on different surface regions within the large surface unit cell. From the corresponding values of S and Theta(sat), data for structure models are deduced. (C) 1997 Elsevier Science B.V.

Microscopic analysis of defects in a high resistivity silicon detector irradiated to 1.7x10(15)n/cm(2)

Current-based microscopic defect analysis methods with optical filling techniques, namely current deep level transient spectroscopy (I-DLTS) and thermally stimulated current (TSC), have been used to study defect levels in a high resistivity silicon detector (p(+)-n-n(+)) induced by very high fluence neutron (VHFN) irradiation (1.7x10(15) n/cm(2)). As many as fourteen deep levels have been detected by I-DLTS. Arrhenius plots of the I-DLTS data have shown defects with energy levels ranging from 0.03 eV to 0.5 eV in the energy band gap. Defect concentrations of relatively shallow levels (E(t) < 0.33 eV) are in the order of 10(13)cm(-3), while those for relatively deep levels (E(t) > 0.33 eV) are in the order of 10(14) cm(-3). TSC data have shown similar defect spectra. A full depletion voltage of about 27,000 volts has been estimated by C-V measurements for the as-irradiated detector, which corresponds to an effective space charge density (N-eff) in the order of 2x10(14) cm(-3). Both detector leakage current and full depletion voltage have been observed to increase with elevated temperature annealing (ETA). The increase of the full depletion voltage corresponds to the increase of some deep levels, especially the 0.39 eV level. Results of positron annihilation spectroscopy have shown a decrease of total concentration of vacancy related defects including vacancy clusters with ETA, suggesting the breaking up of vacancy clusters as possible source of vacancies for the formation of single defects during the reverse anneal.

First charge collection and position-precision data on the medium-resistivity silicon strip detectors before and after neutron irradiation up to 2x10(14) n/cm(2)

Test strip detectors of 125 mu m, 500 mu m, and 1 mm pitches with about 1 cm(2) areas have been made on medium-resistivity silicon wafers (1.3 and 2.7 k Ohm cm). Detectors of 500 mu m pitch have been tested for charge collection and position precision before and after neutron irradiation (up to 2 x 10(14) n/cm(2)) using 820 and 1030 nm laser lights with different beam-spot sizes. It has been found that for a bias of 250 V a strip detector made of 1.3 k Ohm cm (300 mu m thick) can be fully depleted before and after an irradiation of 2 x 10(14) n/cm(2). For a 500 mu m pitch strip detector made of 2.7 k Ohm cm tested with an 1030 nm laser light with 200 mu m spot size, the position reconstruction error is about 14 mu m before irradiation, and 17 mu m after about 1.7 x 10(13) n/cm(2) irradiation. We demonstrated in this work that medium resistivity silicon strip detectors can work just as well as the traditional high-resistivity ones, but with higher radiation tolerance. We also tested charge sharing and position reconstruction using a 1030 nm wavelength (300 mu m absorption length in Si at RT) laser, which provides a simulation of MIP particles in high-physics experiments in terms of charge collection and position reconstruction, (C) 1999 Elsevier Science B.V. All rights reserved.

黄龙世界自然遗产地岷江冷杉原始林群落结构与植物多样性：生境差异性研究

黄龙世界自然遗产地岷江冷杉林(Abies faxoniana)生境类型多样，群落结构复杂，群落植物种类组成多样性丰富。揭示不同生境的生物多样性及其差异是认识生物多样性格局、形成及维持机制的前提和进行多样性保育的基础。本文采用样方法对黄龙钙化滩生境、阴坡非钙化生境及半阳坡非钙化生境的岷江冷杉原始林植物群落结构及植物多样性进行了研究。结果表明： 黄龙岷江冷杉林具有明显的复层异龄结构，垂直结构明显，乔木、灌木、草本、苔藓层次分明。共发现高等植物386 种，其中维管植物46 科103 属163 种，苔藓植38 科83 属物223 种。各层片结构及物种组成如下: (1)钙化滩生境、阴坡非钙化生境、半阳坡非钙化生境分别发现乔木18 种、13种、8 种。乔木层均可分为两个亚层，第一亚层优势种均为岷江冷杉，第二亚层主要为岷江冷杉异龄树或其它大高位芽物种。钙化滩生境第一亚层除优势种岷江冷杉外混生有巴山冷杉(Abies fargesii)、粗枝云杉(Picea asperata)以及阔叶树种白桦(Betula platyphylla)等，第二亚层主要为岷江冷杉异龄树；阴坡非钙化生境第一亚层除优势种岷江冷杉外间有巴山冷杉和白桦，第二亚层物种主要为川滇长尾槭(Acer caudatum var. prattii)；半阳坡非钙化生境第一亚层除优势种岷江冷杉外混生有巴山冷杉，第二亚层主要为岷江冷杉异龄树。依乔木层优势种的差异，钙化滩生境及半阳坡非钙化生境为岷江冷杉纯林，阴坡非钙化生境为岷江冷杉－川滇长尾槭混交林。不同生境乔木层郁闭度、乔木密度、树高结构、直径结构均存在差异。 (2)钙化滩生境发现灌木41 种，平均盖度为18.49±1.72(％)，平均高度为52.12±4.45(cm)，优势种为直穗小檗(Berberis dasystachya)；阴坡非钙化生境发现灌木30 种，平均盖度为29.33±2.56 (％)，平均高度为119.55±8.01 (cm)，优势种为箭竹 (Fargesia spathacea) 、唐古特忍冬(Lonicera tangutica) 和袋花忍冬(Lonicera saccata)；半阳坡非钙化生境发现灌木29 种，平均盖度为31.35±1.93 (％)，平均高度为107.55±4.24 (cm)，优势种为箭竹(Fargesia spathacea)。不同生境灌木层结构和物种组成多样性差异显著，钙化滩生境的灌木盖度、高度总体上较非钙化的坡地生境低, 钙化滩生境灌木以小型叶的落叶灌木为主，沟两侧非钙化的坡地生境上则发育了丰富箭竹。 (3)钙化滩生境发现草本46 种，平均盖度为7.18±0.79 (％)，平均高度为5.04±0.26(cm)，以山酢浆草(Oxalis griffithii)为优势种；阴坡非钙化生境发现草本物种71 种，平均盖度达29.04±2.31(％)，平均高度为9.08±0.52(cm)，以钝叶楼梯草(Elatostema obtusum)、山酢浆草为优势种；半阳坡非钙化生境草本物种50 种，平均盖度为以8.79±0.82(％)，平均高度为7.67±0.43 (cm)，以扇叶铁线蕨(Adiantum flabellulatum)、双花堇菜(Viola biflora)、华中蛾眉蕨(Lunathyrium shennongense)、山酢浆草为优势种。阴坡非钙化生境草本层片发育良好，多样性最为丰富，盖度和物种丰富度均显著高于钙化滩生境和半阳坡非钙化生境。 (4)钙化滩生境发现苔藓物种140 种，平均盖度达84.25±1.30 (％)，以仰叶星塔藓(Hylocomiastrum umbratum) 等大型藓类为优势种；阴坡非钙化生境发现苔藓物种115 种，平均盖度为79.29±1.64 (％)，以刺叶提灯藓(Mnium spinosum)、大羽藓(Thuidium cymbifolium)、毛尖燕尾藓(Bryhnia trichomitra)等个体较小的物种为优势种；半阳坡非钙化生境发现苔藓物种91 种，平均盖度为60.64±1.93 (％)，也以刺叶提灯藓为优势种。 (5)钙化滩生境、阴坡非钙化生境、半阳坡非钙化生境的物种数分别为234 种、221 种、175 种。乔木层的Shannon-Wiener 指数分别为0.75 ±0.12、1.87±0.12、1.78±0.07（灌木层，0.44±0.08、1.71± 0.15、2.49±0.06；草本层，0.33±0.13、1.31±0.15 、2.15±0.08； 苔藓层1.30±0.11、2.08±0.04、1.73±0.11，）；Pielou 均匀度指数分别为0.45±0.05、0.29±0.06、0.28±0.08（灌木层，0.75±0.03、0.68±0.05、0.52±0.06；草本层，0.68±0.02、0.77±0.02、0.74±0.02；苔藓层，0.40±0.03、0.63±0.02、0.52±0.03）；Simpson's 优势度指数分别为0.63±0.06、0.78±0.04、0.83±0.07（灌木层，0.21±0.03、0.28±0.05、0.45±0.06；草本层，0.25±0.02、0.12±0.01、0.17±0.01；苔藓层，0.45±0.04、0.18±0.01、0.31±0.04）。三种生境间乔木层、草本层的Sorenson 群落相似性系数较低, 灌木层、苔藓层的的Sorenson 群落相似性系数较高。 综上所述，黄龙岷江冷杉林的群落结构、植物多样性在三种生境间存在差异性，这将意味着我们在进行黄龙世界自然遗产地的森林经营管理时要较多地关注岷江冷山林群落在不同生境中的差异性。 There were multiplex habitat types, complicated community structure and abundant species composition in the Huanglong World Natural Heritage Site. Uncovering the differences of biodiversity among different habitats was a precondition to understand the distribution, formation and sustaining mechanism of the biodiversity, and the foundation of biodiversity conservation. In the present study, using plenty of quadrants, we investigated the community structure and the biodiversity of the primitive Abies faxoniana forest in different habitats (travertine bottomland, semi-sunny-slope non-calcified habitat and shady-slope non-calcified habitat) in the Huanglong World Natural Heritage Site. The main results are as follows: All the primitive Abies faxoniana forests in the three habitats were uneven-aged with obvious vertical structure including tree layer, shrub layer, herb layer and bryophyte layer. A total of 386 higher plants including 163 vascular plant species (103 generic, 46 families) and 223 bryophyte species (83 generic, 38 families) were investigated. The structure and species composition of each layer are as follows: (1) There were 18, 13 and 8 tree species in travertine bottomland, shady-slope non-calcified habitat and semi-sunny-slope non-calcified habitat, respectively. The tree layers in all habitats can be divided into two clear sub-layers. The upper tree layers were dominated by Abies faxoniana, and the lower tree layers were dominated by uneven-aged Abies faxoniana or other phanerophytes species. There were Abies fargesii , Picea asperata and Betula platyphylla besides the dominated species (Abies faxoniana) in the upper tree layer in travertine bottomland, and the lower tree layers were dominated by uneven-aged Abies faxoniana; There were Abies fargesii and Betula platyphylla besides the dominated species (Abies faxoniana) in the upper tree layer in shady-slope non-calcified habitat, and the lower tree layers were dominated by Acer caudatum var. prattii; There was Abies fargesii besides the dominated species (Abies faxoniana) in the upper tree layer semi-sunny-slope non-calcified habitat, and the lower tree layers were dominated by uneven-aged Abies faxoniana. According to composition percentage of dominate species in tree layer, both the forest in travertine bottomland and in semi-sunny-slope non-calcified habitat could be ranked as pure forest, and the forest in shady-slope non-calcified habitat could be ranked as mingled forest. There were significant differences in crown density, plant density, height structure and diameter structure among the three habitats. (2) A total of 41 shrub species (average coverage 18.49±1.72％; average height 52.12±4.45 ㎝)were found in travertine bottomland, and the dominate species was Berberis dasystachya; A total of 30 shrub species (average coverage 29.33±2.56 ％;average height 119.55±8.01 ㎝)were found in shady-slope non-calcified habitat, and the dominate species was Fargesia spathacea, Lonicera tangutica and Lonicera saccata. A total of 29 shrub species (average coverage 31.35±1.93％; average height 107.55±4.24 ㎝) were found in semi-sunny-slope non-calcified habitat, and the dominate species was Fargesia spathacea. There were significant differences in structure and species diversity of the shrub layers among the three habitats. The coverage and height of shrub had lower value in travertine bottomland than in two non-calcified habitats. Moreover, travertine bottomland was dominated by deciduous shrub species with microphyll and non-calcified habitats developed abundant Fargesia spathacea species. (3) A total of 46 herb species (average coverage 7.18±0.79％;average height 5.04±0.26 ㎝)were found in travertine bottomland, and the dominate species was Oxalis griffithii; A total of 71 herb species (average coverage 29.04±2.31％;average height 9.08±0.52 ㎝)were found in shady-slope non-calcified habitat, and the dominate species was Elatostema obtusum and Oxalis griffithii. A total of 50 herb species (average coverage 8.79±0.82％;average height 7.67±0.43 ㎝) were found in semi-sunny-slope non-calcified habitat, and the dominate species was Adiantum flabellulatum, Viola biflora, Lunathyrium shennongense and Oxalis griffithii. Herb layers developed well in shady-slope non-calcified habitat and had the higher species richness and coverage than travertine bottomland and semi-sunny-slope non-calcified habitat. (4) A total of 140 bryophyte species (average coverage 84.25±1.30％)were found in travertine bottomland, and the dominate species was big bryophyte species such as Hylocomiastrum umbratum and so on; A total of 115 bryophyte species (average coverage 79.29±1.64％)were found in shady-slope non-calcified habitat, and the dominate species was small bryophyte species such as Mnium spinosum, Thuidium cymbifolium, Bryhnia trichomitra and so on. A total of 91 bryophyte species (average coverage 60.64±1.93％) were found in semi-sunny-slope non-calcified habitat, and the dominate species was Mnium spinosum. (5) There were 234, 221 and 175 plant species in travertine bottomland, shady-slope non-calcified habitat and semi-sunny-slope non-calcified habitat, respectively. Shannon-Wiener index of the tree layer was 0.75 ±0.12, 1.87±0.12 and 1.78±0.07 (the shrub layer, 0.44±0.08, 1.71± 0.15 and 2.49±0.06; the herb layer, 0.33±0.13, 1.31±0.15 and 2.15±0.08; the bryophyte layer, 1.30±0.11, 2.08±0.04 and 1.73±0.11.) for the three habitats, respectively; Pielou index of the tree layer was 0.45±0.05, 0.29±0.06 and 0.28±0.08 (the shrub layer, 0.75±0.03, 0.68±0.05 and 0.52±0.06; the herb layer, 0.68±0.02, 0.77±0.02 and 0.74±0.02; the bryophyte layer, 0.40±0.03, 0.63±0.02 and 0.52±0.03.) for the three habitats, respectively. Simpson's index of the tree layer was 0.63±0.06, 0.78±0.04 and 0.83±0.07 (the shrub layer, 0.21±0.03、0.28±0.05、0.45±0.06; the herb layer, 0.25±0.02, 0.12±0.01 and 0.17±0.01; the bryophyte layer, 0.45±0.04, 0.18±0.01 and 0.31±0.04.) for the three habitats, respectively. There were low Sorenson index both in the tree layer and in the herb layer among the three habitats, whereas, high Sorenson index occurred both in the shrub layer and in the bryophyte layer. To sum up, there were differences both in community structure and plant diversity among the three different habitats, which means that we should pay more attention to habitats heterogeneities of the primitive Abies faxoniana forest when we take action to manage the forest in the Huanglong World Natural Heritage Site.

基于ITS 序列和matK 基因序列的中国药用石斛及其混伪品的分子鉴定

为了从分子水平对中国药用石斛及其混伪品进行鉴定，本文选取了核rDNA ITS 序列和叶绿体DNA 的matK 基因序列进行研究。采用改良的CTAB 法提取石斛的基因组DNA，PCR 产物直接测序法对17 种（共32 份）药用石斛的核糖体内转录间隔区ITS 全序列进行测定，克隆测序法对12 种（共22 份）药用石斛的叶绿体的matK 基因序列进行测定，运用BioEd it，MEGA4.0 等生物软件分析了石斛属植物的rDNA ITS 序列及叶绿体的matK 基因序列的特征，比较了石斛属间、种间、种内不同居群（品种）间的序列碱基差异及遗传距离，应用邻接法构建分子系统树。主要研究结果如下： （1）建立了17 种（共32 份）药用石斛rDNA ITS 区碱基全序列数据库，其中，ITS1 的长度为228~234 bp，GC 含量为45.7%~53.0%，变异位点167 个，占总位点67.34%，信息位点106 个，占总位点42.74%，ITS2 长度为241~247 bp，GC含量为44.8%~55.7%，变异位点165 个，占总位点66.27%，信息位点115 个，占总位点46.18%。 （2）建立了12 种（共22 份）药用石斛的叶绿体matK 基因全序列数据库，叶绿体matK 基因长1410 bp，变异位点51 个，信息位点11 个。除了存在碱基替换的遗传变异外，还存在碱基的插入和缺失。 （3）通过ITS 序列比较分析了各材料间的遗传距离和碱基差异，属间的遗传距离为0.295，石斛种间的平均遗传距离为0.142，碱基相差2~156 个，种内各居群间的平均遗传距离为0.002，碱基相差1~2 个。属间的遗传距离大于种间的遗传距离，种间的遗传距离大于种内不同居群（品种）间的遗传距离。 （4）根据分析石斛叶绿体的matK 基因序列得到，外类群（密花石豆兰）与石斛属间最小遗传距离为0.027，石斛种间的平均遗传距离为0.008，种间最大的遗传距离0.014， 最小的遗传距离为0.003，碱基相差8~20 个。种内不同居群（品种）遗传距离为0.001，相差1~5 个碱基。 （5）利用17 种石斛的全序列数据库及遗传分析软件，通过对待检种rDNA I TS区进行序列测定，成功地对10 个待检种进行了鉴定，并且在原植物开花后得到了验证。 （6）运用12 种石斛的matK 基因全序列数据库及遗传分析软件，成功地对4个待检种进行了鉴定，同样在原植物开花后得到了验证。 （7）本文利用石斛的核糖体内转录间隔区ITS 序列和叶绿体的matK 基因序列数据库分别构建了NJ 树，外类群与石斛属间石斛种间以及种内不同居群（品种）间均能在NJ 树中明显分化开来，二者构建的分子系统树一致，为石斛的分子鉴定提供了依据。 In order to identify Chinese Herba Dendrobii and its adulterant species on molecular level, we studied the sequences of rDNA ITS and chloroplast matK gene. Genomic DNA of Dendrobium was extracted using the modified cetyltrimethyl ammonium bromide (CTAB) method. The PCR products of the rDNA ITS sequences of Dendrobium (32 materia ls) were purified and then sequenced. The PCR products of chloroplast matK gene of Dendrobium (22 materia ls) were purified, cloned and then sequenced. The characteristic of the sequences and the genetic dista nce were compared between Bulbophyllum odoratissimum and Dendrobium, Dendrobium interspecies, and different populations. Phylogenetic trees were constructed using the NJ method by the biology softwares including BioEd it, MEGA4.0 etc. The ma in results as follows: (1) It was built up that the database of rDNA ITS sequences of 17 species of Herba Dendrobii (32 materia ls). The ITS1 was 228~234 bp, the GC content accounting for 45.7%~53.0%. Its variable sites were 167, accounting for 67.34%. The Parsim-Informative positions were 106, accounting for 42.74%. The ITS2 was 241~247 bp, the GC accounting for 44.8%~55.7%. The variable sites were 165, accounting for 66.27%. The Parsim-Informative positions were 115, accounting for 46.18%. (2) The database of the chloroplast matK gene sequences was built up, which contained 12 species of Herba Dendrobii (22 materia ls). The matK gene sequences were about 1410bp in length. There were 51 variable sites and 11 Parsim-Informative sites. And there were nucleotides insertions and deletions in some species , in addition to the nucleotides substitutions. (3) The rDNA ITS sequences were compared and analyzed by the biology softwares. The genetic dista nce between Bulbophyllum odoratissimum and Dendrobium was 0.295. The avera ge genetic dista nce was 0.142 between Dendrobium species, and there were 2~156 variable nucleotides. The avera ge genetic dista nce between different populations was 0.002, and there were 2~156 variable nucleotides. The genetic dista nce between Bulbophyllum odoratissimum and Dendrobium was greater tha n that of Denrobium interspecies. Meanwhile, the genetic dista nce between Denrobium species was also greater tha n that of different populations (variaties). (4) The characteristics of the chloroplast matK gene sequences were obtained after analyzing by the biology softwares. The minima l genetic dista nce was 0.027 between Bulbophyllum odoratissimum and Dendrobium . The ma xima l genetic dista nce was 0.014 between Dendrobium species, and there were 20 variable nucleotides. The minima l genetic dista nce between populations was 0.003, and there were 8 variable nucleotides.The genetic dista nce between populations was 0.001, and there were 1~5 variable nucleotides. (5) The molecular Phylogeny tree was constructed on the database of rDNA ITS the sequences of 17 species of Herba Dendrobii using the biology softwares. Then we authenticated 10 materia ls on molecular level. What’s more, they had been proved when these pla nts flowered. (6) The molecular Phylogeny tree was built up on the database of chloroplast matK gene sequences of 12 species of Herba Dendrobii with the biology softwares.Then 4 materia ls were authenticated on molecular level. Moreover, they had also been proved when these pla nts were in flower. (7) The Phylogenetic trees were separately constructed on the sequences of rDNA ITS and chloroplast matK gene B. odoratissimum and Dendrobium all could be distinguished on the Phylogenetic trees. Meanwhile, the Phylogenetic trees based on two groups of sequences were coincident. rDNA ITS and matK gene sequence could be used as molecular markers for authentication of Herba Dendrobii.