Showing papers by "Braunschweig University of Technology published in 1969"
TL;DR: In this article, the short-lived isotopes of argon, krypton, silver, cadmium, tin, iodine, xenon, platinum, gold, mercury, polonium, radon and francium have been studied by the on-line isotope separator technique.
138 citations
01 Jan 1969
TL;DR: The Social Organisation and Population Ecology of the Plains Zebra (Equus Quagga) Zoologica Africana: Vol. 4, No. 2, pp. 249-263 as mentioned in this paper.
Abstract: (1969). The Social Organisation and Population Ecology of the Plains Zebra (Equus Quagga) Zoologica Africana: Vol. 4, No. 2, pp. 249-263.
92 citations
TL;DR: In this article, the electroluminescence of silicon was investigated in the temperature range between 300 and 77 °K, and an absolute measurement of the internal quantum efficiency yields a room temperature value of 2 × 10−6 for the band-to-band emission.
Abstract: The electroluminescence of silicon was investigated in the temperature range between 300 and 77 °K. The near edge emission is due to indirect band-to-band transitions associated with TO and TA phonon emission/absorption. The intensity-voltage relation shows that this emission is connected with the diffusion current. At low voltages, additional long wavelength emission is observed which is connected with recombination in the space charge region. An absolute measurement of the internal quantum efficiency yields a room temperature value of 2 × 10−6 for the band-to-band emission. This value is well described by a theoretical radiative lifetime derived from van Roosbroeck-Shockley statistics and by an experimental non-radiative lifetime.
Die Elektrolumineszenz von Silizium p-n Ubergangen wurde zwischen 300 und 77 °K untersucht. Die Emission nahe der Bandkante wird durch indirekte Band-Band-Ubergange unterstutzt durch TO- und TA-Phononen gedeutet. Diese Strahlungskomponente ist mit dem Diffusionsstrom gekoppelt, wie die Intensitat-Spannungs-Abhangigkeit zeigt. Bei kleinen Spannungen wird eine langwellige Emission, die mit Rekombination in der Raumladungszone gekoppelt ist, beobachtet. Eine Absolutmessung der inneren Quantenausbeute ergibt den Wert 2 × 10−6 fur 300 °K. Er kann theoretisch bei Kenntnis einer nichtstrahlenden Lebensdauer durch eine Berechnung der strahlenden Lebensdauer nach van Roosbroeck-Shockley bestimmt werden.
49 citations
TL;DR: In this paper, the triorganylsilyl derivatives of ammonia and hydrazine with phenyllithium were metallated and the resulting N-substituted lithium compounds could be isolated.
Abstract: Ten years ago N-metallated silicon-nitrogen compounds were still unknown. Today the lithium as well as the sodium derivative of hexamethyldisilazane belong—second only to hexamethyldisilazane itself—to the most investigated of SiN-compounds. In 1959 we metallated for the first time the triorganylsilyl derivatives of ammonia and hydrazine with phenyllithium. The resulting N-substituted lithium compounds could be isolated. They were of interest to us primarily with respect to their transformation into multiple silylsubstituted derivatives of ammonia and of hydrazine. Later we noticed that they presented an extraordinary variety of preparative problems, and their physical properties turned out to be unusual and unpredictable. The more involved we became with the structure of these compounds the more enigmatic they seemed. Even today we can only describe many of them and explain little. In each new investigation they bring more surprising results, and the possibilities for their synthesis seem far from exhaustion. Well to the fore of interest are SiN-compounds substituted on the N-atom by alkali metals, and here again the doubly silylsubstituted amides have become the most important. It is not possible to prepare them by substitution of the H-atoms of the alkali amides. One must start with disilazanes and metallate them:
43 citations
TL;DR: The first complete mass spectra of unprotected dinucleotides e.g. TpT, GpU, ApC, and CpA are reported in this article, which make possible the determination of the molecular weight.
Abstract: The first complete mass spectra of unprotected dinucleotides e.g. TpT, GpU, ApC, and CpA are reported. In all cases these spectra make possible the determination of the molecular weight. In addition structural information about the building blocks of the dinucleotides can be obtained.
31 citations
TL;DR: In this article, eine Ubersicht uber jene thermisch oder katalytisch induzierten Umwandlungsreaktionen gegeben, die organische Verbindungen vor der Ionisierung im Massenspektrometer verandern konnen.
Abstract: Es wird eine Ubersicht uber jene thermisch oder katalytisch induzierten Umwandlungsreaktionen gegeben, die organische Verbindungen vor der Ionisierung im Massenspektrometer verandern konnen. Auf die dadurch gegebenen Gefahren bei der Strukturermittlung unbekannter Verbindungen, aber auch auf zusatzliche Informationen, die auf diese Weise gewonnen werden konnen, wird hingewiesen.
19 citations
15 citations
01 Sep 1969
TL;DR: In this article, the magnetischen Krafte auf den Pol einer Gleichstrommaschine are shown to have a notwendigen Differenzengleichungen werden fur kartesische and polare Gitternetzwerke hergeleitet.
Abstract: Die Berechnung magnetischer Felder kann heute mit Hilfe der Differenzenrechnung auf grosen Digitalrechnern erfolgen. Die hierfur notwendigen Differenzengleichungen werden fur kartesische und polare Gitternetzwerke hergeleitet. Zur Konvergenzbeschleunigung werden drei Methoden der Blockrelaxation angegeben. Als Beispiel werden die magnetischen Krafte auf den Pol einer Gleichstrommaschine berechnet.
12 citations
TL;DR: By delayed coincidence techniques, the following half-lives of excited nuclear levels in 72Ga, populated by the decay of 72Zn, were measured: 16.4 keV, T 1 2 = 39.2
11 citations
TL;DR: In this article, the calibration of a light detector for recording fluorescence spectra is described, and physical principles are thoroughly reviewed and disagreements in the literature are referred to, and an example for a special application is discussed.
Abstract: The calibration of a light detector for recording fluorescence spectra is described. In this connection the physical principles are thoroughly reviewed and disagreements in the literature are referred to. An example for a special application is discussed.
7 citations
TL;DR: In this article, with finite degree of spatial coherence Leith and Upatnieks holography and furthermore Fourier Holography are performed with a finite degree spatial coherency.
TL;DR: In this paper, it was shown that in a metal Si3N4-nSi structure, the net minority-carrier generation rate is equal to the hole injection rate under balanced conditions.
Abstract: In a metal-Si3N4-nSi structure, the net minority-carrier generation rate is equal to the hole injection rate into the insulator under balanced conditions. The generation rate has been determined experimentally, giving the ratio of the injected hole current and the total current in the Si3N4 film.
01 Nov 1969
TL;DR: In this article, a parametric amplifier with an MIS varactor exhibits gain saturation for high pump voltage, and two MIS varactors connected antiparallel have an even C-V characteristic.
Abstract: A parametric amplifier with an MIS varactor exhibits gain saturation for high pump voltage. Two MIS varactors connected antiparallel have an even C-V characteristic. The differential capacitance varies with twice the pump frequency, and the gain has a flat maximum at a certain pump voltage.
01 Oct 1969
TL;DR: The application of solid dielectrics for insulating purpose at high voltages has increased rapidly during the past 20 years as mentioned in this paper, in spite of the fact that breakdown processes in practical arrangements with solid insulation are not at all understood.
Abstract: The application of solid dielectrics for insulating purpose at high voltages has increased rapidly during the past 20 years. This happened in spite of the fact, that breakdown processes in practical arrangements with solid insulation are not at all understood. In many cases we are not even able to recognize the different stages of breakdown by measuring techniques.
01 Jan 1969
TL;DR: In this paper, the authors propose a new approach, in which Abweichungen vom Gleichgewicht are zugelassen, deren Einflus nicht mehr vernachlassigbar ist.
Abstract: Bisher war bei allen Betrachtungen vorausgesetzt worden, das Gleichgewicht herrscht oder das die Abweichungen vom Gleichgewicht vernachlassigbar klein sind (quasistatische Zustandsanderungen). Jetzt sollen auch solche Abweichungen vom Gleichgewicht zugelassen werden, deren Einflus nicht mehr vernachlassigbar ist. Sie fuhren zu Stromen, deren Starke als Mas fur die Abweichung vom Gleichgewicht und die dadurch entstehenden Verluste angesehen werden kann. Ein Beispiel soll diesen Sachverhalt erlautern. In einem abgeschlossenen System, das nur eine Phase enthalt, sind im Gleichgewicht keine Unterschiede der Temperatur, des chemischen Potentiales oder des elektrischen Potentiales vorhanden. Dieses Gleichgewicht wird dadurch erreicht, das eventuell vorhandene Temperaturdifferenzen durch einen Warmestrom, Differenzen des elektrischen Potentiales durch einen elektrischen Strom und durch Konzentrationsunterschiede hervorgerufene Unterschiede des chemischen Potentiales durch Diffusionsstrome abgebaut werden.
01 Jan 1969
TL;DR: Theoretically, the Energiebegriff is ein Teilgebiet der Physik as discussed by the authors, wobei sie ist bekannt voraussetzt.
Abstract: Die Thermodynamik ist ein Teilgebiet der Physik. Sie behandelt daher nicht nur die Frage der Umwandlung der Energieform „Warmein“ die Energieform „mechanische Arbeit“, sondern ganz allgemein die Umwandlung und den Transport von Energie, wobei sie den Energiebegriff als bekannt voraussetzt.
01 Jan 1969
TL;DR: In this article, closed form solutions for the maximum efficiency of idlerless multipliers with step recovery diodes are given, where the multiplication factor is arbitrary and the number of multipliers is fixed.
Abstract: Closed form solutions are given for the maximum efficiency of idlerless multipliers with step recovery diodes. The multiplication factor is arbitrary.
01 Oct 1969