Nonlinear spatially resolved phase spectroscopy

A new method for the determination of spatially resolved phase differences of nonlinear susceptibilities is presented. The technique is based on the interference of the signal field with a reference field. A phase-shifting element that directly changes the phase difference between the two second-harmonic fields is introduced. The reliability of the method is tested by an experiment with two quartz crystals. As a first application, a measurement of the phase difference between domains in antiferromagnetic YMnO(3) is presented.     

Resonance-enhanced two-photon sum-frequency generation in NiO and KNiF<Subscript>3</Subscript>

Resonance-enhanced sum-frequency generation is introduced as a novel tool for investigation of magnetically ordered compounds. A tunable laser at frequency ₁ is used to excite an intermediate electronic transition resonantly while a second laser at frequency ₂ is used to scan the nonlinear spectrum at ₁+₂. The technique is particularly useful for investigation of centrosymmetric compounds since resonance enhancement at ₁ leads to large nonlinear signals even in the case of weakly allowed nonlinear processes. The technique is demonstrated on antiferromagnetic NiO and KNiF₃ and also shown to be useful for investigation of samples with large thickness or absorption. PACS 42.65.Ky; 78.20.Ls; 42.62.FiThis revised version was published in October 2004 with a correction to the name of Takuya Satoh.     

Determination of the magnetic symmetry of hexagonal manganites by second harmonic generation

Optical second harmonic spectroscopy is introduced as a powerful supplement for the determination of complex magnetic structures. Experimental efforts are simplified and new degrees of freedom are opened. Thereby, some principal or technical restrictions of neutron or magnetic x-ray diffraction experiments are overcome. High spatial resolution leads to additional information about magnetically ordered matter. As an example, the noncollinear magnetic structure of the hexagonal manganites RMnO3 ( R = Sc, Y, Ho, Er, Tm, Yb, Lu) is analyzed. The results show that some earlier conclusions on their magnetic symmetry and properties should be revised.     

Ein Beitrag zur kolloidchemischen Nomenklatur

Ohne Zusammenfassung     

Studien über die Flockung kolloider Lösungen,I. Gegenseitige Flockung entgegengesetzt geladener Kolloide

Colloid and Polymer Science - Die gegenseitige Flockung von vier verschiedenen Eisenoxydsolen, deren Konstitution nach Wintgen-Biltz bestimmt worden war, mit acht verschiedenen negativen Solen...     

Wolfgang Ostwald 60 Jahre alt

Ohne Zusammenfassung