热处理低温钠长石的EPR和X射线衍射研究

利用电子顺磁共振(EPR)和X射线衍射方法研究了天然和热处理钠长石单晶。热处理在500—850℃水热条件下完成。在外加磁场B平行于晶体c~*轴的方向上,测量了加热前后Fe~(3+)的EPR谱和线宽△B随温度和加热时间的变化。结果显示,线宽随Al、Si无序的增大而增加。由此得出结论,在低温钠长石中,Fe~(3+)位于Al~(3+)占据的T_1(o)位置,在被研究的温度范围内,Fe~(3+)未参与四面体位置T间Al、Si交换。谱线的加宽主要是由在Fe~(3+)邻近位置上Al、Si无序的增大引起的,同时与观测到的晶胞参数变化有关。在Al、Si无序更强的晶体中,Fe~(3+)谱变得极宽。     

山东蓝宝石铁离子的价态及其对色调的影响

山东蓝色蓝宝石的着色是由Ｔｉ４＋离子与Ｆｅ２＋离子合理配比而成，一般控制在Ｔｉ４＋／Ｆｅ２＋＝１的配比范围内。多余的Ｆｅ２＋和其它Ｆｅ３＋离子存在都不利于蓝色蓝宝石正常呈色。通过穆斯堡尔谱和电子顺磁共振谱分析，测定了山东蓝宝石中铁离子的不同价态和浓度。对Ｆｅ２＋和Ｆｅ３＋离子所引起的吸收光谱特征作了研究，查明只有Ｆｅ３＋浓度很高时才产生４７７ｎｍ吸收峰，是致使山东蓝宝石表观上呈深蓝带黑色调的的重要原因。     

Sodium and potassium in the bones of penguin and skua revealed by EPR and SR-XRF technique

Penguin and skua in the maritime Antarctic have high salt loadings in the body due to almost exclusive diet consumption of marine invertebrates. However, the storage and turnover of sodium and potassium in these animals are poorly investigated. Here we determined the concentration and microscopic distribution of the two elements in the bones of penguin and skua. The average concentrations of sodium and potassium in penguin bone were comparable with that in skua bone (0.18% and 0.82% for penguin bone; 0.19% and 0.76% for skua bone in dry weight). The ratios of sodium to calcium and potassium to calcium (0.0330 and 0.0075 for penguin, 0.0335 and 0.0082 for skua in average by weight) were somewhat higher than the reported ratios for terrestrial animals, indicating these marine animals' bone enrichment of salt. The ratios of sodium to potassium in average by weight were 6.75 and 4.65 for penguin and skua, respectively. This value is much lower compared with the bulk sea water ratio of about 27.0, implying that potassium is favorable to reside in the bone rather than sodium. Both sodium and potassium were found to significant correlation with the content of organic materials in bone based upon the intensity of native signal determined by electron paramagnetic resonance (EPR). It was estimated that almost all of potassium is kept within the organic phases, while about 30% of sodium is stored in organic phases and the other 70% within mineral phase. The microscopic distributions of potassium in the cross-section and/or surface were revealed by synchrotron radiation X-ray fluorescence (SR-XRF) technique. The ratio of potassium to calcium based upon the SR-XRF intensity counter varied considerably from the surface to the interior, and on the surface the highest concentration of potassium was observed in the middle section with decreasing amounts toward the edge. This indirectly documented that exchange of potassium between fluid and bone organic phase maybe occur.     

EPR investigation of the role of germanium centers in the production of the 110°C thermoluminescence peak in quartz

The identification of the center acting as electron source for the well-known 110 °C thermoluminescence (TL) peak of quartz is of fundamental importance for practical applications in dating and dosimetry. This TL peak was studied in parallel with the electron paramagnetic resonance (EPR) signal of the [GeO₄]⁻ center on natural colourless quartz irradiated at room temperature. Immediately after irradiation, the signals of the 110 °C TL peak and of [GeO₄]⁻ center decay exponentially in the same way, yielding a lifetime of 50.4 ± 0.9 min at room temperature. Besides, we acquired the isothermal decay curves for the 110 °C TL peak and [GeO₄]⁻ center at different temperatures (the samples were held at the selected temperature in the range of 260–308 K). The lifetimes extracted by the isothermal decays were plotted as a function of reciprocal temperature, revealing again the same behavior of the 110 °C TL peak and [GeO₄]⁻ center, both characterized by activation energies very close of 0.76 ± 0.07 eV and 0.77 ± 0.07 eV, respectively. All results of the present work clearly show the role of electron source of [GeO₄]⁻ center in the emission mechanism of the 110 °C TL peak in quartz.     

Towards understanding paleosols in Southern Levantine eolianites: Integration of micromorphology, environmental magnetism and mineralogy

The paper addresses the controversial question of the role of clay-sized dust in the formation of paleosols in coastal eolianites, Israel. At the Habonim type section, the pedocomplex dated by archaeology and luminescence to 45-135 ka ago shows at least three paleosols, not separated by non-soil sediments. The oldest reddish paleosol （apparently related to MIS 5） is magnetically enhanced, leached from carbonates, with signs of bioturbation and strongly aged clay coatings. The reddening is due to very fine, -20 nm, poorly crystallized, superparamagnetic （SP） hematite, as determined by Mossbauer studies. In subsoil, lithorelics of eolianite are found. Over time, the soil surface aggraded due to accelerated fine dust accumulation alongside local slope wash. On younger materials formed magnetically depleted vertisols, dominated by smectite-type expandable paramagnetic clays. In thin sections, vertisols exhibit strong stipple-speckled and striated b-fabric due to shrink-swell processes, impregnative calcite nodules and Fe-Mn redistribution. The uppermost hydric vertisol shows the strongest expression of juxtaposed features of recurrent calcite and Fe precipitation. This paleosol developed on colluvial soil materials, as evidenced by mixing of clay coated and uncoated grains of quartz and calcite allochems. M6ssbauer spectra show high amounts of Fe（III） incorporated in the clay structure, low amounts of SP goethite and absence of SP hematite. Whilst magnetic susceptibility drops in vertisols to minimal values, increase. The latter along ferrimagnetie grain sizes with differences in the hierarchy of microfabric features is taken as indication for lithologic discontinuities which may have resulted from continuous, albeit variable and low-intensity, input of eolian clay from both remote Saharan and local sources, roughly dated to the earlier to middle part of the Last Glacial.     

南秦岭晚三叠世胭脂坝岩体岩石磁学及磁组构可靠性约束

胭脂坝岩体是秦岭造山带内具典型代表性意义的晚三叠世花岗岩,已有的年代学和地球化学研究对该岩体的侵位机制有不同认识。对岩体的岩石磁学进行分析,结合其岩相学特征,探讨了用磁组构约束岩体内部组构这一方法的可靠性。研究表明,胭脂坝岩体样品的平均磁化率Km值和校正磁化率各向异性度PJ值总体较低,与顺磁性花岗岩类一致。磁滞回线分析表明,绝大部分样品的磁化率来自顺磁性矿物的贡献,少部分高磁化率样品含有铁磁性矿物的贡献,但其浓度极低。高磁化率值样品的等温剩磁曲线获得和反向退磁曲线及χ-T曲线分析表明,铁磁性矿物为磁铁矿,且为多畴颗粒。结合岩相学特征,认为胭脂坝岩体低场磁组构反映了顺磁性的云母类矿物的组构特征,磁组构特征真实地记录了样品的内部组构特征。     

青田石、寿山石、昌化鸡血石和巴林石的产地特征初步比较研究

文章通过X射线粉晶衍射、电子顺磁共振等方法对青田石、寿山石、昌化鸡血石和巴林石的产地特征进行了初步研究,发现在矿物组成、有序度、多型特征、Fe3+的赋存状态和致色机理等方面存在差异.     

Electron paramagnetic resonance spectroscopy as a novel approach to measure macromolecule–surface interactions and activities of extracellular enzymes

The dynamics of high molecular weight organic matter in marine systems are influenced by molecular conformation, interactions with surfaces and susceptibility to enzymatic hydrolysis, parameters that are difficult to observe experimentally. Here we use electron paramagnetic resonance spectroscopy (EPR) and spin-labeled (SL-) polysaccharides to monitor the sorption of SL-polysaccharides to natural sediment surfaces and to montmorillonite and to observe decreases in polysaccharide size due to enzymatic hydrolysis. SL-pullulan, SL-xylan and SL-maltoheptaose all sorbed rapidly to muddy sediments but not to sandy sediments. SL-pullulan and SL-maltoheptaose also both sorbed to montmorillonite; however, SL-pullulan reached substantially greater final surface loadings than did SL-maltoheptaose. Using EPR has the advantages of being rapid (spectra can be acquired in 100 seconds), non-destructive and functional in complex media, including sediment slurries, muddy water or other optically opaque samples, permitting investigation of the interactions between biomacromolecules, extracellular enzymes and mineral surfaces in aquatic environments.     

腐泥煤变质系列的核磁共振谱和顺磁共振谱特征

利用核磁共振和顺磁共振谱对等变质系列的腐泥煤和腐殖煤进行了对比研究,两种谱图清楚地表现出两个变质系列各煤阶的峰形和峰值都有明显的区别。     

含铬明矾局部压缩率的研究

本文运用晶体场理论计算了几种含铬明矾的自旋-晶格耦合系数G_(44)在此基础上,求得了它们的零场劈裂对键角的变化率。根据单轴压力下的EPR谱数据,获得了在这几种明矾中的(T~(3+)·6H_2O)~(3+)基团的局部压缩率,这些值都明显地小于明矾晶体的压缩率。在本文中,我们讨论了产生这种现象的原因并论证了这些局部值的合理性。由此可以看出,压力下的EPR谱是研究含顺磁离子矿物的局部结构和局部压缩率的有效手段。