Mode competition effects in CW dye lasers

The output characteristics of a rhodamine 6G jet stream cw dye laser equipped with a mirror grating combination for mode selection, have been studied experimentally. The tuning range proved to be considerably narrower than that to be expected from the gain profile under the (erroneous) assumption of independently oscillating modes. Actually, the reduction of the tuning range is a consequence of mode competition, as pointed out in a previous theoretical paper. Moreover, the intensity of the selected mode has been found to be independent of the wavelength. All experimental findings are in a good agreement with the results of a theoretical analysis.     

A class ofA-stable two-step methods based on Schur polynomials

Lineark-step methods (k2) with constant coefficients are derived by choosing as the second characteristic polynomial of the method a Schur polynomial whose coefficients depend on a certain set of parameters. The choice of these parameters is based on a result due to Marden concerning the location of the zeros of a class of rational functions, and it is shown that, for the (practically important) casek=2, the corresponding two-step methods are alwaysA-stable.     

Highly enantioselective syntheses of heterocycles via intramolecular Ir-catalyzed allylic amination and etherification

[reaction: see text] Enantioselective Ir-catalyzed intramolecular allylic aminations and etherifications are described. Up to 97% ee was achieved using catalysts prepared by in situ activation of mixtures of phosphorus amidites and [Ir(COD)Cl]2. Sequential aminations of bis-allylic carbonates, involving an inter- followed by an intramolecular reaction, gave trans-N-benzyl-2,5-divinylpyrrolidine and trans-N-benzyl-2,6-divinylpiperidine with > or = 99% ee. New phosphorus amidites as well as improved conditions for intermolecular aminations are reported.     

Tunneling anisotropic magnetoresistance: a spin-valve-like tunnel magnetoresistance using a single magnetic layer

We introduce a new class of spintronic devices in which a spin-valve-like effect results from strong spin-orbit coupling in a single ferromagnetic layer rather than from injection and detection of a spin-polarized current by two coupled ferromagnets. The effect is observed in a normal-metal-insulator-ferromagnetic-semiconductor tunneling device. This behavior is caused by the interplay of the anisotropic density of states in (Ga,Mn)As with respect to the magnetization direction and the two-step magnetization reversal process in this material.     

DNA-templated catalysis using a metal-cleavable linker

Catalytic release of carboxylates from their 8-hydroxyquinoline esters by Cu(II) complexes, both attached to peptide nucleic acid strands, is triggered by complementary DNA.     

Beiträge zur Kenntnis der symm. Diamino-aryl-triazine

Ohne Zusammenfassung