Christian Zimmermann

Learn More
Cementitious materials are widely used as binders both in construction and in environmental technology (e.g., for stabilization and solidification). When dealing with materials contaminated with organic solvents, it is important to have an idea about the interaction between the solvents and the hydrating cement. Here, we introduce nuclear magnetic resonance(More)
Biogeosciences Discussions This discussion paper is/has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG if available. Abstract In initial ecosystems concentrations of all macro-and micronutrients can be considered as extremely low. Plant litter therefore strongly influences the development of a(More)
We present experiments with Bose-Einstein condensates on a combined atom chip. The combined structure consists of a large-scale “carrier chip” and smaller “atom-optics chips,” containing micron-sized elements. This allows us to work with condensates very close to chip surfaces without suffering from fragmentation or losses due to thermally driven spin(More)
The second harmonic of the 842-nm output of a GaAlAs diode laser is generated in a KNbO(3) crystal in a resonant, external ring cavity. The diode laser is optically stabilized to the ring cavity through feedback from the counterpropagating fundamental wave, which is weakly excited in the resonator. We have produced 6.7 mW of tunable, narrowband radiation at(More)
We demonstrate application-grade monomode distributed feedback (DFB) laser devices with emission wavelength around 5.2 μm; suitable for nitric oxide sensing. The devices are based on interband cascade laser material that enables continuous wave operation in the midinfrared spectral region when mounted on a standard thermoelectrically cooled TO-style(More)
A microscopic magnetic quadrupole trap for neutral atoms has been realized with a combination of permanent magnets, coils, and ferromagnetic pole pieces. The attainable magnetic field gradients of 3 3 105 Gycm infer a spatial extension of the ground state much smaller than the wavelength of optical transitions. The field gradient can be varied over a wide(More)
Two frequency components of an IR laser beam near 980 nm are simultaneously coupled into two adjacent longitudinal modes of a passive ring resonator. A potassium niobate crystal inside the resonator converts the circulating IR light into coherent blue radiation. The total conversion efficiency is enhanced by a factor of 1.4 compared with that of(More)
Generation of 22 mW of narrow-band radiation near 430 nm was achieved by frequency doubling the 100-mW output of a single-mode GaAIAs diode laser near 860 nm. A monolithic potassium niobate ring resonator serves as the nonlinear medium and at the same time as a reference cavity for the diode-laser frequency, which optically self-locks to a cavity resonance(More)
Tunable laser radiation with megahertz linewidth is generated with a simple, inexpensive, and compact laser system that uses two common microscope slides as the only intracavity tuning elements. The laser emits two radiation modes whose frequencies are separated by 1.2 GHz, corresponding to the free spectral range of the laser resonator. The frequencies may(More)