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131.
LEED analysis of the laser annealed Si(1 1 1)-(1 × 1) surface shows that a model with a graphite-like top double layer of atoms with a spacing of 2.95±0.02 Å from the second double layer describes the LEED data as well as the Zehner model, but involves large displacements of the atoms normal to the surface as required by ion scattering results. It is suggested that this model provides a natural interpretation of the low energy He atom scattering data for the Si(1 1 1)-(7 × 7) surface. 相似文献
132.
133.
134.
M. J. Griffin W. S. Holland 《International Journal of Infrared and Millimeter Waves》1988,9(10):861-875
The effects of radiant power loading on the performance of an ideal bolometer are analysed. The operation of the bolometer is characterized in terms of dimensionless parameters which correspond to the temperature sensitivity of the thermometric material, the electrical bias point and the amount of optical power loading. Expressions are derived for the zero frequency NEP and responsivity. Examples are given for the case of a bolometer cooled to 100 mK and used for ground-based astronomical photometry at submillimetre wavelengths. 相似文献
135.
C. Dewdney M.A. Dubois P.R. Holland A. Kypriandis L. Laurent M. Pain J.P. Vigier 《Physics letters. A》1985,113(3):135-138
We report on an experiment to test for a separate proton spectrum for hydrogen. The null results is in direct violation with the predictions of local hidden variable theories, and supports either non-local quantum potential theories or an “orthodox” (Copenhagen) interpretation of quantum mechanics, where the reality of particles is not conserved. 相似文献
136.
K. A. Surano G. B. Hudson R. A. Failor J. M. Sims R. C. Holland S. C. MacLean J. C. Garrison 《Journal of Radioanalytical and Nuclear Chemistry》1992,161(2):443-453
Helium-3 (3He) mass spectrometry for the analysis of low-level tritium (3H) concentrations (0.5 to 5 Bq·l–1) in environmental sample matrices was compared with conventional low-level -decay counting methods. The mass-spectrometry method compared favorably, equalling or surpassing conventional decay-counting methods with respect to most criteria. Additional research and method refinements may make3He mass spectrometry the method of choice for routine, low-level to very-low-level (L<0.5 Bq·l–1)3H measurements in a wide variety of environmental samples in the future. 相似文献
137.
Summary An extractive-spectrophotometric method for the determination of vanadium in tool steel is described. The only sample pretreatment required is dissolution. An average vanadium value of 2.06% was obtained on a standard sample compared to the recommended value of 2.06%.
Eine rasche spektrophotometrische Bestimmung von Vanadin in Werkzeugstahl mit 1-[(6-Methyl-2-pyridyl)azo]-2-hydroxynaphthalin-N-oxid
Zusammenfassung Eine extraktions-spektrophotometrische Methode zur Bestimmung von Vanadin in Werkzeugstahl wurde beschrieben. Die einzige Vorbehandlung der Probe besteht in deren Auflösung. Der durchschnittlich gefundene Vanadingehalt in einer Standardprobe betrug 2,06% und stimmte mit dem angegebenen Vanadingehalt genau überein.相似文献
138.
Summary The application of the named compound for the spectrophotometric determination of scandium is described. The effects due to pH, reagent concentration, time and diverse ions are reported. Beer's law is obeyed and the molar absorbance coefficient at 555 nm is 1.55×104. By using a cupferron extraction prior to analysis, the procedure is quite selective.
Spektrophotometrische Bestimmung von Scandium mit Dinatrium-3-hydroxy- 4-[(6-methyl-2-pyridyl)azo]-2,7-naphthalindisulfonat-N-oxid
Zusammenfassung Die Anwendung der genannten Verbindung für die spektrophotometrische Bestimmung von Scandium wurde beschrieben. Der Einfluß des pH, der Reagenskonzentration, der Zeit und verschiedener Ionen wurde untersucht. Das Beersche Gesetz wird befolgt, der molare Absorptionskoeffizient bei 555 nm beträgt 1,55×104. Nach vorhergehender Cupferron-Extraktion ist das Verfahren selektiv.相似文献
139.
Summary 3-Thianaphthenoyltrifluoroacetone has been proposed for the spectrophotometric determination of iron(III). The 31 complex is very stable and can be extracted from acid solution into chloroform. Beer's law is obeyed and the molar extinction coefficient is 5.0·103 at 516 nm. Relatively large amounts of cobalt, nickel and copper are tolerated. The method is simple, convenient and reproducible.
Zusammenfassung 3-Thianaphthenoyltrifluoraceton wurde für die spektrophotometrische Eisen(III)-bestimmung vorgeschlagen. Der 31-Komplex ist sehr beständig und läßt sich aus saurer Lösung mit Chloroform extrahieren. Die Farbe entspricht dem Beerschen Gesetz, die molare Extinktion beträgt 5,0·103 bei 516 nm. Relativ große Mengen Kobalt, Nickel und Kupfer stören nicht.相似文献
140.
The synthesis, structure, and reactivity of a series of low-coordinate Fe(II) diketiminate amido complexes are presented. Complexes L(R)FeNHAr (R = methyl, tert-butyl; Ar = para-tolyl, 2,6-xylyl, and 2,6-diisopropylphenyl) bind Lewis bases to give trigonal pyramidal and trigonal bipyramidal adducts. In the adducts, crystallographic and (1)H NMR evidence supports the existence of agostic interactions in solid and solution states. Complexes L(R)FeNHAr may be oxidized using AgOTf, and the products L(R)Fe(NHAr)(OTf) are characterized with (19)F NMR spectroscopy, UV/vis spectrophotometry, solution magnetic measurements, elemental analysis, and, in one case, X-ray crystallography. In the structures of the iron(III) complexes L(R)Fe(NHAr)(OTf) and L(R)Fe(OtBu)(OTf), the angles at nitrogen and oxygen result from steric effects and not pi-bonding. The reactions of the amido group of L(R)FeNHAr with weak acids (HCCPh and HOtBu) are consistent with a basic nitrogen atom, because the amido group is protonated by terminal alkynes and alcohols to give free H(2)NAr and three-coordinate acetylide and alkoxide complexes. The trends in complex stability give insight into the relative strength of bonds from three-coordinate iron to anionic C-, N-, and O-donor ligands. 相似文献