Intensitätsverhalten von Molekülanionen organischer Substanzen unter verschiedenen Versuchsbedingungen

A modified commercial mass spectrometer was used to perform quantitative measurements on negative ions of selected organic compounds at about 10^?4 Torr source pressure. The pressure dependency of the molecular ion intensity on pure compounds and binary mixtures shows up two different sources of slow secondary electrons. At low total source pressures a log-log plot of the ion intensity against the sample amount is linear and slow electrons are produced predominantly by wall effects, whereas at high pressures plasma effects arise with a non-linear pressure dependency.     

Stereoselectivity in the formation of tris-diimine complexes of Fe(II), Ru(II), and Os(II) with a C2-symmetric chiral derivative of 2,2'-bipyridine

A C2-symmetric enantiopure 4,5-bis(pinene)-2,2'-bipyridine ligand (-)-L was used to investigate the diastereoselectivity in the formation of [ML3]2+ coordination species (M = Fe(II), Ru(II), Os(II), Zn(II), Cd(II), Cu(II), Ni(II)), and [ML2Cl2] (M = Ru(II), Os(II)). The X-ray structures of the [ML3]2+ complexes were determined for Delta-[FeL3](PF6)2, Delta-[RuL3](PF6)2, Lambda-[RuL3](PF6)2, Delta-[OsL3](PF6)2, and Lambda-[OsL3](TfO)2. All of these compounds were also characterized by NMR, CD and UV/VIS absorption spectroscopy. The [FeL3]2+ diastereoisomers were studied in equilibrated solutions at various temperatures and in several solvents. The [RuL3]2+ complexes, which are thermally stable up to 200 degrees C, were photochemically equilibrated.     

Third order nonlinear optical difference frequency generation in KH2PO4, TiO2, LiNbO3, CaCO3, ZnO and CdS

Third-order nonlinear optical susceptibilities of different crystals have been measured relative to LiNbO₃ by observing collinear phase-matched difference frequency generation ₁=2 ₂– ₄. The two incident light waves have been produced by a ruby laser ( ₂, ₂=694.3 nm) and by induced Raman scattering ( ₄, ₄=765.8 nm). With noncollinear phase-matching the number of nonlinear processes and the possibilities to determine nonlinear coefficients is much larger than in the collinear case. Therefore the theory of Raman-type third order interactions has been extended to noncollinear propagation of the interacting waves. The theory has been tested experimentally for CdS.     

Parametrische 4-Photonenfluoreszenz in Rutil

Tunable four-photon parametric fluorescence due to the third-order optical nonlinearity has been observed in a rutile (TiO₂)-crystal. AQ-switched ruby-laser was used as a pump. The produced idler wave could be tuned from 5900 to 6550 Å by rotation of the crystal.     

15N Distribution in Wheat and Chemical Fractionation of Root-Borne 15N in the Soil

Abstract

Spring wheat plants were grown in split-root containers and labelled with ¹⁵N by fertilizing one compartment of the container with ¹⁵NH₄ ¹⁵NO₃ (95 at.-% ¹⁵N exc.). After the harvest, approx. 90% of the ¹⁵N incorporated by the plants were found in the shoots and 3% in the roots; approx. 7% had been released into the soil of the unlabelled compartment. The ¹⁵N in the soil of the unlabelled compartment was extracted with KCl and hydrolysed with HCl. Approx. 60% of the ¹⁵N was found in the hydrolysable organic N pool of the soil and 9% in the fraction of the soluble and exchangeable inorganic nitrogen.     

A comparison of negative and positive ion mass spectrometry

Negative ion mass spectrometry using a conventional mass spectrometer with a special ion source and a sample pressure of approximately 2 × 10^?5 Torr is shown to be an excellent method for the qualitative analysis of lower mass alcohols, mercaptans, ketones, aldehydes, aliphatic carboxylic acids and esters, the spectra of which are characterized by intense [M – H] ^? ions. The method may be termed a ‘selective’ low energy ionization technique, being suitable for the above organic compounds, but not for nitriles, nitro compounds, hydrocarbons, ethers, amines, amides, nitrogen heterocycles and chlorinated compounds. This method can be looked upon as a complementary method, to positive ion mass spectrometry.     

Zur Synthese von Human-Big-Gastrin I und seinem 32-Leucin-Analogon

The preparation of the pure tetratriacontapeptide amide 2 (human big gastrin I) and the analogue Leu³²-human big gastrin I from the crude synthetic materials obtained after deblocking of the overall protected tetratriacontapeptide amide derivatives by means of trifluoroacetic acid is described. The criteria for homogeneity obtained by chromatographic, electrophoretic, enzymatic and spectroscopic methods are reported.

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Abkürzungen HBG-I Human-Big-Gastrin I - LHBG-I 32-Leucin-Human-Big-Gastrin I - HBG-[1-20] N-terminale Teilsequenz [1–20] des Human-Big-Gastrins I - HG-17-I Human-Gastrin I - LHG-17-I 15-Leucin-Human-Gastrin I - HG-13-I Human-Minigastrin I - LHG-13-I 11-Leucin-Human-Minigastrin I Es werden hier die von der IUPAC-IUB Commission on Biochemical Nomenclature empfohlenen Abkürzungen für Aminosäuren und Schutzgruppen verwendet.Andere Abkürzungen.Anm.: Auf Grund der kürzlich erfolgten Strukturkorrektur (R. A. Gregory, H. J. Tracy, J. I. Harris, M. J. Runswick, S. Moore, G. W. Kenner undR. Ramage, Hoppe-Seylers Z. physiol. Chem.360, 73, 1979) sind HG-13-I und LHG-13-I neuderdings richtiger als Des-1-Tryptophan-Human-Minigastrin I bzw. [Des-1-Tryptophan]-11-Leucin-Human-Minigastrin I zu bezeichnen].Vorläufige Mitt.:E. Wünsch, G. Wendlberger, A. Hallett, E. Jaeger, S. Knof, L. Moroder, R. Scharf, I. Schmidt, P. Thamm undL. Wilschowitz, Z. Naturforsch.32c, 495 (1977).3. Mitt.:G. Wendlberger, L. Moroder, A. Hallett undE. Wünsch, Mh. Chem.110, 1407 (1979).     

Estimation of quantum efficiencies and Arrhenius parameters of organic laser dyes by measuring fluorescence decay times down to T = 115 K

The fluorescence decay times of several organic dyes in alcoholic solution in the temperature range between 300 K and 115 K are measured. These measurements offer the possibility to determine Arrhenius parameters and to estimate quantum efficiencies.