Optical model analysis of antiprotonic oxygen atom data

An optical model analysis has been made for antiprotonic ¹⁶, ¹⁸O atoms using accurate measurements of the strong interactions shift and width for the 3d level and for the width of the 4f level. Ambiguities in the potential depth and isotope effects are studied. Problems in fitting the 3d and 4f levels simultaneously may indicate some inherent limitation in the validity of the simple optical model.     

Does Bd and Bs mixing require the existence of a fourth generation?

Recent data from ARGUS gives an unexpectedly large B_d mixing. Combined with a previous limit on B_d, B_s mixing from MARK II, it appears that while B_d mixing is sizeable, B_s mixing may be non-maximal. This may contradict the three-generation standard model. We discuss the implications of this possibility on the existence of a fourth generation. More reliable information can come from a study of B mixing at the

(5S) and is therefore strongly urged.     

地质样品中岩性自动分类X－射线荧光光谱分析研究

鉴于地质样品岩性变化大，容易引起对Ｘ－射线荧光分析准确度的影响，尤其是主、次量元素受影响更大，因此，作者提出了岩性自动分类，交互有效－基本参数法分析地质样品中主、次量元素，并与原有的经验系数和其它方法进行了比较．结果表明本方法的准确度更好些，对岩性的变化具有更好的适应能力     

荧光法测定N-(α-烷苯氧基)十四酰基牛磺酸钠的临界胶束浓度

研究了一类以苯氧基作疏水支链的新型阴离子表面活性剂——N-(α-烷苯氧基)十四酰基牛磺酸钠(SAPTT)水溶液的紫外吸收光谱、探针(芘)稳态荧光发射光谱及自身稳态荧光发射光谱性质.研究结果表明,荧光探针(芘)法和自身稳态荧光法可用来测定这类表面活性剂的临界胶束浓度(CMC),且测定结果与表面张力法(吊片法)接近;与荧光探针(芘)法相比,对于所研究体系,自身稳态荧光法的灵敏度和准确性均较高,所测得CMC结果与表面张力法(吊片法)能较好地吻合.     

驱油体系化学剂间相互作用对界面吸附膜的影响

采用界面张力弛豫技术研究了不对称Gemini表面活性剂C12COONa-p-C9SO3Na、部分水解聚丙烯酰胺Mo-4000、疏水缔合水溶性聚丙烯酰胺(HMPAM)等驱油体系化学剂在癸烷/水界面上的扩张流变性质,考察了不同离子强度、不同类型电解质对体系界面流变性质的影响,计算得到界面扩张弹性模量和粘性模量的全频率谱,并通过归一化方法(cole-cole图)探讨了界面吸附膜的弛豫过程。研究发现,界面膜内分子重排和界面与体相间分子扩散交换是影响膜性质的主要弛豫过程。表面活性剂体相浓度增大有利于界面分子重排过程,而低频有利于扩散交换过程;不同结构聚合物以及不同离子强度、不同类型电解质对表面活性剂吸附膜有不同的影响。     

盐湖资源开发利用进展

本世纪头十年里,国际上再度掀起盐湖资源开发热潮。这很大程度上是由于锂的开发热带动的,同时也是和钾肥的广泛施用、价格一路走高有关。南美安第斯高原地区盐湖蕴藏世界70%以上的锂资源,且卤水锂、钾、硼浓度高。该地区极度干旱,少雨多风,非常适合采用卤水盐田蒸发的节能浓缩工艺技术。老的盐湖开发企业则在钾肥需求的带动下,稳步发展。在我国,新疆罗布泊和青海柴达木盆地盐湖则钾锂镁硼产品多元化,经营多元化取得长足进步。本文对近十年来,国内外盐湖开发的新动向做了概括介绍,特别着重于南美"锂三角"地区这一新的生长点。     

分子自组装法制备具有可控浸润性的铜表面简

通过简单浸泡的方法在铜基底上制备出了具有微纳米复合结构的氧化铜,再利用混合硫醇溶液[含HS(CH2)9CH3和 HS(CH2)11OH]对浸泡后的表面进行修饰,通过控制溶液中HS(CH2)11OH的浓度,制备出一系列具有不同浸润性的铜表面,实现表面从超疏水到超亲水的有效调控. 研究发现,表面浸润的可控性源于表面复合结构与不同化学组成的协同作用,微纳米复合结构的存在为表面浸润性的调节提供了必要的条件.     

Photoconductivity and photoreflectance studies of quantum-wells and superlattices

We have performed room-temperature in-plane photoconductivity and photoreflectance measurements on various types of GaAs/AlAs quantum-wells and superlattices. The photoconductivity spectra of samples with even a few (1 to 7) quantum-wells show sharp excitonic structures superimposed on the bulk GaAs signal, and provide a useful alternative to absorption spectra. The photoreflectance spectra are demonstrated experimentally to follow the third derivative of the photoconductivity spectra, as previously reported for bulk materials, even though the mechanism of photoreflectance must be different in the present two-dimensional systems.     

Scanning tunneling microscope light emission spectra of polycrystalline Ge2Sb2Te5 and Sb2Te3

We have observed scanning tunneling microscope light emission (STM-LE) spectra of Ge₂Sb₂Te₅ and Sb₂Te₃. Although these chalcogenide alloys exhibit band gaps less than 0.5 eV, the STM-LE was observed with a narrow spectral width at a photon energy of 1.5 eV for both materials. By analyzing its bias voltage, polarity, and temperature dependencies combined with recently reported theoretical electronic structures, we concluded that the STM-LE is excited by electronic transitions taking place in the local electronic structure having a direct gap-like shape with a band gap of 1.5 eV, commonly found in the electronic structures of both materials.     

Well-thickness dependent electron transport effective mass and mobility in Sb-based quantum wells

We propose a special kind of Sb-based III–V semiconductor quantum wells, which, in contrary to conventional ones, are able to provide novel transport properties: smaller electron transport effective mass and higher mobility with thinner well width. By properly choosing the barrier materials with smaller electron effective mass and proper band lineups, the novel transport property could be achieved because of the penetration effect of the wave-function when interface roughness and alloy disorder scatterings are taken into consideration.