Wrocław University of Technology

About: Wrocław University of Technology is a education organization based out in Wrocław, Poland. It is known for research contribution in the topics: Laser & Computer science. The organization has 13115 authors who have published 31279 publications receiving 338694 citations.

Portable gas chromatograph with integrated components

Abstract: In the paper, a portable gas chromatograph with silicon/glass integrated micromachined flushed injector and doubled thermal conductivity detectors (TCD) has been presented. The injector has two symmetrical dosing loops, each of 7 μl volume and one fast injection microvalve, pneumatically operated. All parts of the injector are integrated on 35×35×2.5 mm3 glass/silicon/glass die. Teflon coated thin polyimide foil is applied as the moving actuator of the microvalve of the injector. Three types of TCDs have been tested. In the first type of TCD, four thin-film Pt heaters/thermoresistors made on thin silicon nitride CVD deposited membrane suspended over deeply etched in a silicon substrate two channels, are applied. In the next two TCDs, miniature spirals made of thin Pt solid wire are assembled inside glass/silicon chip. Two configurations of spirals position have been tested: in-line serial and in-line parallel. Computer simulations, supported by experiments have indicated better parameters of TCD with parallel configuration of spirals. The TCDs with Pt spirals are resistant against carrier gas decays. In the portable gas chromatograph two capillary columns are used: active (molecular sieve) and passive. Columns and co-working TCD are thermally stabilized in an oven equipped with a thick-film heater made on polyimide foil. The instrument is equipped with built-in microcomputer with two 16-bit microprocessors and is operated (controlled) by an external portable PC. All important parameters of analysis (possible single or continuous mode of work) are adjusted electronically, as well as data acquisition and preparing of the complete analysis effect in the form of chromatograms and tables indicating qualitative and quantitative composition of gas mixture. The instrument is able to work in on-line continuous measurements, tests made for artificial atmosphere of deep mining industry have shown successful work of the instrument.

Magnetic order in a Kondo lattice: a neutron scattering study of CeCu2Ge2

Abstract: Elastic and inelastic neutron scattering studies of the Kondo lattice CeCu2Ge2 were performed. AtTN=4.1 K an incommensurate magnetic order develops with an ordering wave vectorq0=(0.28, 0.28, 0.54) and an ordered moment µs=0.74 µB. The crystalline electric field splits the 4f1-J-multiplet of the Ce ion into a ground state doublet and a quartet at 191 K. The wave function of the ground state yields an ordered moment of 1.54µB. Thus, due to the onset of the formation of a Kondo singlet the magnetic moment is considerably reduced. The magnetic relaxation rate Λ was investigated via quasielastic neutron scattering. The temperature dependence of Λ(T) is characteristic of heavy-fermion systems with a high temperature square root dependence and a limiting low temperature value, yielding a Kondo temperatureTK≈10K. The quasielastic component of the scattered neutron intensities persists down to the lowest temperatures, well belowTN. This quasielastic line is regarded as a characteristic feature of heavy-fermion systems and corresponds to the enhanced value of the linear term of the specific heat.