AFM and XRD investigation of crystalline vapor-deposited C60 films

The morphological and structural properties of C(60) films deposited on quartz substrates by sublimation at 320-500 degrees C under high vacuum have been investigated using atomic force microscopy (AFM) and reflection X-ray diffraction (RXRD). The thickness of the films varied between 0.2 microm and 10 microm. AFM showed that the films consist predominantly of cubic crystals of a few micrometer in size with well-developed (111) and (100) faces. The crystallographic investigation revealed a strongly preferred [111] growth direction which is very sensitive to the deposition rate and substrate temperature. The influence of the experimental parameters on the morphology of the crystals and on the preferred orientation of the films is discussed in view of the AFM and RXRD results.     

Application of equilibrium theory to ternary moving bed configurations (four+four, five+four, eight and nine zones) I. Linear case

In this article, different ternary moving bed configurations are studied by determining the working flow-rates of the equivalent true moving bed at the low solvent consumption point using equilibrium theory. This method has been applied for linear adsorption isotherms. The simulated moving bed flow-rates can then be calculated and a final comparison between the performances of each process is given based upon two different objective functions.     

中低变质程度煤显微组分结构的13 C-NMR研究

利用13C-NMR核磁共振技术对中低变质程度煤显微组分（镜质组和惰质组）的分子结构进行了研究,计算了5种煤9个显微组分的13C-NMR结构参数,获得了样品的结构特征及变化规律。结果表明,惰质组结构中芳构化程度要高于镜质组;脂碳数量则少于镜质组,芳环上的烷烃侧链也没有镜质组长;随着煤变质程度的提高,煤分子中芳构化程度不断提高,但惰质组的芳香度随变质程度变化的规律明显不如镜质组;在中低变质阶段,对煤化进程起主导作用的的是芳构化作用而不是环缩合作用,但在惰质组中脂碳断裂形成芳环的现象不明显。惰质组中含氧官能团的总量要低于同等变质程度的镜质组。     

Exploring Cu/Al cluster growth and reactivity: from embryonic building blocks to intermetalloid,open-shell superatoms

Cluster growth reactions in the system [Cu₅](Mes)₅ + [Al₄](Cp*)₄ (Mes = mesitylene, Cp* = pentamethylcyclopentadiene) were explored and monitored by in situ LIFDI-MS and ¹H-NMR. Feedback into experimental design allowed for an informed choice and precise adjustment of reaction conditions and led to isolation of the intermetallic cluster [Cu₄Al₄](Cp*)₅(Mes) (1). Cluster 1 reacts with excess 3-hexyne to yield the triangular cluster [Cu₂Al](Cp*)₃ (2). The two embryonic [Cu₄Al₄](Cp*)₅(Mes) and [Cu₂Al](Cp*)₃ clusters 1 and 2, respectively, were shown to be intermediates in the formation of an inseparable composite of the closely related clusters [Cu₇Al₆](Cp*)₆ (3), [HCu₇Al₆](Cp*)₆ (3H) and [Cu₈Al₆](Cp*)₆ (4), which just differ by one Cu core atom. The radical nature of the open-shell superatomic [Cu₇Al₆](Cp*)₆ cluster 3 is reflected in its reactivity towards addition of one Cu core atom leading to the closed shell superatom [Cu₈Al₆](Cp*)₆ (4), and as well by its ability to undergo σ(C–H) and σ(Si–H) activation reactions of C₆H₅CH₃ (toluene) and (TMS)₃SiH (TMS = tris(trimethylsilyl)).

Cu/Al cluster growth reactions leading to open- and closed-shell superatoms are investigated. Therein, LIFDI-MS is presented as a powerful technique for the in situ detection of cluster identities and reactivity patterns.     

Isotope ratio monitoring gas chromatography/Mass spectrometry of D/H by high temperature conversion isotope ratio mass spectrometry

Of all the elements, hydrogen has the largest naturally occurring variations in the ratio of its stable isotopes (D/H). It is for this reason that there has been a strong desire to add hydrogen to the list of elements amenable to isotope ratio monitoring gas chromatography/mass spectrometry (irm-GC/MS). In irm-GC/MS the sample is entrained in helium as the carrier gas, which is also ionized and separated in the isotope ratio mass spectrometer (IRMS). Because of the low abundance of deuterium in nature, precise and accurate on-line monitoring of D/H ratios with an IRMS requires that low energy helium ions be kept out of the m/z 3 collector, which requires the use of an energy filter. A clean mass 3 (HD(+.)) signal which is independent of a large helium load in the electron impact ion source is essential in order to reach the sensitivity required for D/H analysis of capillary GC peaks. A new IRMS system, the DELTA(plus)XL(trade mark), has been designed for high precision, high accuracy measurements of transient signals of hydrogen gas. It incorporates a retardation lens integrated into the m/z 3 Faraday cup collector. Following GC separation, the hydrogen bound in organic compounds must be quantitatively converted into H(2) gas prior to analysis in the IRMS. Quantitative conversion is achieved by high temperature conversion (TC) at temperatures >1400 degrees C. Measurements of D/H ratios of individual organic compounds in complicated natural mixtures can now be made to a precision of 2 per thousand (delta notation) or, better, with typical sample amounts of approximately 200 ng per compound. Initial applications have focused on compounds of interest to petroleum research (biomarkers and natural gas components), food and flavor control (vanillin and ethanol), and metabolic studies (fatty acids and steroids). Copyright 1999 John Wiley & Sons, Ltd.