Optical constants of thin oxide films on titanium

Thin oxide films on titanium formed by heating were studied by the ellipsometric method. To obtain the complex refractive index and film thicknesses, the ellipsometric measurements were performed by means of the immersing method: each sample was measured first in air and then in a liquid of known refractive index (in our case CCl₄). The optical constants and the oxide film thickness were computed by means of a computer from two pairs of ellipsometric values. To state the optical constants of clean titanium surface the graphic-computational method was proposed and applied. The measurements were carried out at two wavelengths on oxide films grown in air and dry oxygen by thermal oxidation at temperatures from 150 to 700 °C. It has been shown that when increasing the film thickness the refractive index of the film decreases, whereas the absorption coefficient is independent on the film thickness. Optical constants of oxide films growing in dry oxygen are smaller than those growing in air.     

Dependence of V-A characteristics of amorphous semiconductor Ge15Te81S2As2 on hydrostatic pressure

The paper presents the functional expression of V-A characteristics dependent on hydrostatic pressure up to 5 kbar for chalcogenide glass Ge₁₅Te₈₁S₂As₂. The measured V-A characteristics and those derived on the assumption of a linear decrease of the energy gap due to pressure have been compared. Temperature changes caused by current passing through the sample in thermal contact with the environment have been taken into consideration similarly as in the case of paper (2).In conclusion we wish to express our thanks to Doc. J.Krempaský CSc., Ing. P.Dieka, Ing. J.Bielek for their kind help in discussing various points of the problem.     

2-(4'-Isocyanatophenyl)-6-methylbenzthiazol als neues,hochempfindliches Fluoreszenzreagens zur Identifizierung und Bestimmung organischer Verbindungen

Zusammenfassung Ein neues Fluoreszenzreagens mit hochreaktiver Isocyanatgruppe wurde hergestellt, dessen Eignung zum Nachweis und zur Bestimmung aliphatischer und aromatischer Amine, Aminosäuren, Alkohole und Phenole geprüft wurde. Die Identität der mit diesen Substanzen hergestellten Derivate wurde elementaranalytisch bestätigt. Sie eignen sich für die chromatographische Identifizierung. Das Maximum der Fluoreszenz dieser Derivate liegt bei 383 nm. Die große Reaktivität und die intensive, mit dem Reagens erzielbare Fluoreszenz bieten die Möglichkeit zur Anwendung in der Spurenanalyse, z. B. für Umweltuntersuchungen.

---

2-(4'-Isocyanatophenyl)-6-methylbenzthiazole as a new highly sensitive fluorescent reagent for identification and determination of organic compounds

Summary A new fluorescent reagent with a highly reactive isocyanate group was produced and its suitability for demonstration and determination of aliphatic aromatic amines, amino acids, alcohols and phenols was tested. The identity of the derivatives produced with these substances was confirmed by elemental analysis. They are suitable for Chromatographic identification. The fluorescence maximum of these derivatives is at 383 nm. The great reactivity and the intensive fluorescence which can be achieved with the reagent enabled it to be used in trace analysis, e. g. for environmental studies.

     

Semiempirical versusab initio calculations of molecular properties

A comparative study of the structural parameters in some strained spirohydrocarbons is presented. The theoretical values provided by the STO-3G, MINDO/3 and IMOA methods are in reasonable agreement with each other and with available experimental data offering thus a posteriori justification of the employed approximate schemes.