共查询到20条相似文献,搜索用时 4 毫秒
1.
2.
本文介绍了一种用CCD测量光密度的新方法.利用改变曝光时间t和改变透射率τ对曝光量的改变是完全等价的这一原理,不用借助任何标准密度灰片校准,可在大面积上足够精准地测量物体透射密度. 相似文献
3.
The millerite is of mineral--crystallographic and structure-chemical interest because ofits unusual coordinate number and distances. The experimental electron density distributionof millerite has been determined from high resolution X--ray diffraction data. According tothe distribution of lone pair electrons and their long distances from the nucleus of Ni andS atoms, we suggest that there are multiple coordinate bonding between Ni and S atoms andnormal coordinate bonding between Ni and Ni atoms. These are in reasonable agreement withthe unusual coordinate number, distorted coordinate polyhedron, bonding distances betweenatoms and some metallic properties of millerite. 相似文献
4.
5.
6.
7.
8.
9.
10.
煤焦的晶格结构,本征反应活性和密度初探 总被引:6,自引:1,他引:6
通过对低变质程度烟煤的镜质组分分别在空气和高纯氧中所得中温焦炭的密度和晶格化程度的初步研究,并作了链条锅炉飞灰炭的本征反应活性和密度关系比较,认为煤在不同气氛中加热其晶各化结构增强的决定性作用是温度,其次是煤在加热中的停留时间,煤焦的密度大小可作为煤焦晶格化程度的一种表征,煤焦的本征反应活性与煤焦密度和晶格化程度具有相关性。 相似文献
11.
Yongchang Fan Alexander G. Fitzgerald Phillip John Clare E. Troupe John I. B. Wilson 《Mikrochimica acta》2000,132(2-4):435-441
The surface morphology and electronic properties of as-deposited CVD diamond films and the diamond films which have been
subjected to boron ion implantation or hydrogen plasma etching have been systematically studied by high resolution scanning
probe microscopy and spectroscopy techniques. AFM and STM image observations have shown that (a) both the as-deposited CVD
diamond films and the boron ion implanted films exhibit similar hillock morphologies on (100) crystal faces and these surface
features are formed during the deposition process; (b) boron ion implantation does not cause a discernible increase in surface
roughness; (c) atomic flatness can be achieved on crystal faces by hydrogen plasma etching of the film surface. Scanning tunnelling
spectroscopy analysis has indicated that (a) the as-deposited diamond films and the hydrogen plasma etched diamond films possess
typical p-type semiconductor surface electronic properties; (b) the as-deposited diamond films subjected to boron implantation
exhibit surface electronic properties which change from p-type semiconducting behaviour to metallic behaviour; (c) the damage
in the boron implanted diamond films is restricted to the surface layers since the electronic properties revert to p-type
on depth profiling. 相似文献
12.
J. Al Andari A. M. Diamy J. C. Legrand R. I. Ben-Aim 《Plasma Chemistry and Plasma Processing》1993,13(1):103-116
Electron temperature and ion density are measured in an air microwave-induced plasma (2450 MHz) by means of a floating double probe. A 'cinetic scheme for ion formation and decay is set up, and a relationship between atomic oxygen and ion densities is obtained. From this relationship an order-of-magnitude of atomic oxygen concentration in the discharge is derived and compared with results obtained by optical actinometry in another work. 相似文献
13.
14.
极低密度聚乙烯与其它聚乙烯的共混 总被引:3,自引:0,他引:3
从结构角度,用DSC,WAXD,SAXS研究了聚乙烯(PE)家族中极低密度聚乙烯(VLDPE)与其它PE的互容性.HDPE/VLDPE是共晶互容的,以其大量无规部分“溶解”了HDPE的结晶缺陷部分,提高了HDPE的Tc,Tm,Xc,结晶峰半高宽变窄,晶胞参数随组成而有最低值.VLDPE与LLDPE结构极为相似,DSC及WAXD证明其共混物是共晶相容体系.LDPE/VLDPE的结晶度符合按组成的计算值,但晶胞参数a,b以及晶粒尺寸增大,DSC上有分别相应于两组份的两个Tm;VLDPE的Tc,Tm峰高之和高于按组份的计算值,LDPE的Tm,Tc则低于计算值.认为是正如LLDPE/LDPE,LDPE向充满整个体积的VLDPE中不断填入,以VLDPE为晶核而结晶,形成相分离的不相容体系. 相似文献
15.
毫秒脉冲激光合成超细纳米金刚石 总被引:1,自引:0,他引:1
通过热力学和动力学的基本理论, 分析了毫秒脉冲激光照射石墨悬浮液合成超细纳米金刚石的机理. 在毫秒脉冲激光与石墨颗粒相互作用形成的碳蒸气羽中, 通过碳蒸气凝聚形成了金刚石核. 与纳秒脉冲激光相比, 毫秒脉冲激光具有较低的功率密度和较长的脉宽, 为金刚石核的生长提供了较小的过冷度, 使得金刚石核的生长速率减小; 而较小的生长速率也为金刚石表面形成sp2杂化结构提供了机会, 它可以有效降低金刚石核的表面能, 促使金刚石核稳定, 但表面的sp2杂化也阻止了金刚石核的外延. 以上两个原因决定了毫秒激光辐照石墨颗粒过程中只能获得超细的纳米金刚石. 相似文献
16.
17.
Low density polyethylene(LDPE)/lignin blends were prepared using melt blending.Two kinds of compatibilizers, ethylene-vinylacetate(EVA) which is softer than LDPE and polyethylene grafted with maleic anhydride(PE-g-MA) which is harder than LDPE were used to improve the interfacial adhesion.Scanning electron microscope(SEM) was used to investigate the dispersion of lignin in LDPE matrix.The results showed that both of the compatibilizers could improve the interaction between the low density polyethylene an... 相似文献
18.
19.
为考察金刚石形成氢终止表面的反应机制,采用微波氢等离子体处理以及电阻丝氢气气氛加热处理进行对比研究.利用光发射谱(OES)和漫反射傅里叶变换红外光谱(DRIFTS)分别表征了微波氢等离子体中的活性基团和金刚石表面氢终止浓度.结果表明,微波氢等离子体环境下,随着衬底温度、等离子体密度和能量的增加,温度至700 ℃ (800 W/3 kPa)时,等离子体中出现了明显的CH基团;相应地,金刚石表面氢终止浓度随温度、等离子体密度和能量的增加而增加.采用氢气气氛下电阻丝加热的方法同样形成了氢终止金刚石表面,表明微波等离子体处理金刚石表面形成氢终止主要源于由温度控制的表面化学反应,而非等离子体的物理刻蚀作用.氧终止金刚石表面形成氢终止的机制是表面C=O键在高于500 ℃时分解为CO,相应的悬挂键由氢原子或氢分子占据. 相似文献
20.
用真比重分离法研究一种飞灰残炭的生成途径和再燃特性 总被引:2,自引:0,他引:2
根据煤在足够高温度下,停留时间越长,分子结构的晶格化程度越高,因而反应活性越低,同时真比重也越大的原理,采用重液将一种链条锅炉飞灰中的残炭颗粒富集并按不同真比重分开。各比重组颗粒表面积测定结果符合不同燃尽度焦炭比表面积变化规律;小流化床燃烧实验证明随真比重增大,残炭颗粒本征反应活性降低。说明真比重分离法对于判断飞灰残炭颗粒的形成途径和再燃特性很有效。实验结果表明,链条炉飞灰残炭并不主要由原煤中的细小颗粒形成,由中等和大颗粒原煤形成的飞灰残炭占相当比例;在真比重最大的残炭组中,细小颗粒所拥有的总碳量最大。估计它们是由大颗粒或大块原煤经过炉内高温区、停留时间长,燃烧后期碎裂形成的。 相似文献