bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monomodige DFB-Quantenkaskadenlaser mit Metall-Bragg-Rückkopplungsgittern (Single Mode Quantum Cascade DFB-Lasers with Metal Bragg gratings)
Authors: Seufert Jochen , Koeth Johannes , Fischer Marc , Höfling Sven , Reithmaier Johann P. , Forchel Alfred 
Published: May 2005

Abstract
Auf der Basis von GaAs/AlGaAs-Heterostrukturen wurden monomodige Quantenkaskadenlaser im Wellenlängenbereich von 9–11 μm entwickelt. Die Rotations-Schwingungs-Grundzustände vieler industriell wichtiger Gase fallen in diesen Spektralbereich im mittleren Infrarot. Daher eignen sich diese Laser in besonderem Maße für den sensitiven Nachweis von beispielsweise CO2 (9,5 μm Wellenlänge), O3 (9,7 μm) und NH3 (10,7 μm). Die Laser werden auf standardisierte c-mounts montiert, die sehr einfach in komplexere Optikmodule eingebaut werden können. Im gepulsten Betrieb liefern die hergestellten Bauteile bei Peltiertemperaturen Ausgangsleistungen von einigen mW und erweisen sich aufgrund ihres kontinuierlichen Durchstimmbarkeitsverhaltens der Emissionswellenlänge insbesondere für spektroskopische Anwendungen als geeignet.
Untersuchungen des Intensitätsrauschens von Quantenkaskadenlasern (Investigations of the Intensity Noise of Quantum Cascade Lasers)
Authors: Gensty Tobias , von Staden Jens , Elsäßer Wolfgang 
Published: May 2005

Abstract
Quantenkaskadenlaser (QCLs) repräsentieren die jüngste Generation von Halbleiterlasern, die viel versprechende Lichtquellen für die Gasanalytik darstellen. Wir untersuchen ihr Intensitätsrauschen und finden ein neues Skalierungsverhalten als Funktion der emittierten optischen Leistung. Im Hinblick auf Anwendungen in Laserspektroskopie-Systemen charakterisieren wir das Verhalten eines QCL in Externer-Resonator-Konfiguration. Schließlich zeigen wir, dass moderne Hohlleiter-Fasern geeignete Lichtwellenleiter für die Laserspektroskopie im mittleren infraroten Spektralbereich darstellen.
External-Cavity-QCL-Systeme (External Cavity QCL Systems)
Authors: Hildebrandt Lars , Knispel Richard , Stry Sandra , Sacher Joachim 
Published: May 2005

Abstract
Für zahlreiche Anwendungen in der industriellen Messtechnik werden durchstimmbare Laser im mittleren infraroten Spektralbereich benötigt. Aufgrund charakteristischer Spektren vieler umwelt- und medizinisch relevanter Moleküle ist dieser Bereich von besonderem Interesse. Um einen Laser mit einem großen monomodig spektral durchstimmbaren Wellenlängenbereich zu realisieren, sind Quantenkaskadenlaser entspiegelt und in einem externen Resonator betrieben worden.
Superfine oxide powders— flame hydrolysis and hydrothermal synthesis
Authors: Kriechbaum Gangolf W. , Kleinschmit Peter 
Published: May 2005

Nanocrystalline materials which can be plastically deformed at low temperatures have revolutionized the applications for ceramics. Two methods for the production of high‐tech ceramics with grain sizes of less than 1 pm are described and the quality of the materials, for example ZrO2 powder (see figure), assessed. magnified image
Spatially selective conducting patterns in transparent films derived from ladder type polymers
Authors: Belaish Igal , Davidov Dan , Selig Heny , McLean Malcolm R. , Dalton Larry 
Published: May 2005

Conducting patterns embedded in a completely transparent polymer film can be produced using selective heating by laser annealing of cross‐linked, stable, ladder‐like polymers followed by fluorination. The figure shows a transparent film treated in this way containing the permanent, conducting pattern. magnified image
The function of polymers in the tape casting of alumina
Authors: Böhnlein‐Mauß Jutta , Sigmund Wolfgang , Wegner Gerhard , Meyer Wolfgang H. , Heßel Friedrich , Seitz Katharina , Roosen Andreas 
Published: May 2005

Polymeric additivesshave a great influence on the processing parameters in the produciton of high‐performance ceramics. The various types of additives are described and the interactions between the organic additives and the inorganic ceramic powders, some examples of which are shown in the figure, are examined with emphasis on one of the most important ceramic forming processes.magnified image
3,4‐Dimethoxypyrrole: Monomer synthesis and conducting polymer formation
Authors: Merz Andreas , Scnwarz Roland , Schropp Roland 
Published: May 2005

Processible conducting polymers based on 3, 4‐substituted polythiophenes have been known for some time. Here, the synthesis and polymerization of an analogue to the thiophenes, the dialkoxypyrrole monomer shown in the figure, are reported. The polymer formed exhibits a relatively high conductivity pointing to a regular, possibly coiled structure. magnified image
A construction principle of the κ‐phase based on the efficient (OH)donor…Oanion structural functionality: The examples of κ‐(EDT–TTF(CH2OH))2X (X = ClO and ReO)
Authors: Blanchard Philippe , Boubekeur Kamal , Sallé Marc , Duguay Guy , Jubault Michel , Gorgues Alain , Martin James D. , Canadeli Enric , Auban‐Senzier Pascale , Jérome Denis , Batail Patrick 
Published: May 2005

The search for κ‐phases of conducting and superconducting organic cation radical salts is difficult because it is not yet known which characteristics of the donor molecule are required for this structure to be generated. The figure shown the hydroxy‐methyl‐functionalized non‐centroxymmetrical donor EDT‐TTF(CH2OH), which has been purposely associated with the discrete tetrahedral perchlorate and perrhenate anions to form two new examples of a κ‐phase. magnified image
Crystals of an antiferromagnetic 1,3‐butadiyne compared with a ferromagnetic 1,3,5‐hexatriyne carrying a 4‐Chloro‐3‐(N‐tent‐butyl‐N‐oxyamino)phenyl Group as a Persistent Free Radical Substituent
Authors: Inoue Katsuya , Iwamura Hüzu 
Published: May 2005

Persistent organic radicals with a ferromagnetic interaction in the crystalline state are few and far between. One example is crystalline 1,3,5‐hexatriyne carrying a [4‐chloro‐3‐(N‐tert‐butyl‐N‐oxyamino)‐phenyl] substituent at position 1. This has been studied and compared with crystalline 1,3‐butadiyne (see Figure) carrying the same substituent, which, in contrast, exhibits antiferromagnetic interactions at cryogenic temperatures. magnified image
Sensors for organic solvent detection in the ppm range based on dioxo[6.1.6.1]paracyclophanes—from molecular modeling to analyte recognition
Authors: Dickert Franz L. , Haunschild Alexander , Reif Martin , Bulst Wolf‐E. 
Published: May 2005

Hydrophobic coatings for mass‐sensitive sensor devices, which yield a negligible water cross sensitivity, are the aim of the reported research. Molecular modeling was used to gain an understanding of the binding mechanism of some solvent molecules with a tetraazaparacyclophane containing alkyl substituents at the amino bridgeheads (CPO44VAL)— the figure shows the calculated geometry of the benzene complex of CPO44VAL. The theoretical results were then compared with the actual performance of CPO44VAL in devices. magnified image
Capped nanometer silicon electronic materials
Authors: Brus Louis 
Published: May 2005

New properties, structures, and concepts in solid silicon materials have been glimpsed in several experiments. In addition to the recent systematic effort to use organometallic chemical methods to make and characterize free‐standing “capped” crystallites or quantum dots—the figure shows one structure of a capped polysilyne oligomer–new chemical approaches to capped nanometer silicon micelles, puckered sheets, clusters and crystallites are presented. magnified image
Dissipative structure formation in colloidal systems
Authors: Wessling Bernhard 
Published: May 2005

Self‐organization phenomena are observed in most real systems. Is this true also for colloidal or microemulsion systems? It is argued that the current general practice of assuming that polymeric and non‐polymeric colloidal systems are in equilibrium is not valid and that non‐equilibrium thermodynamics should be applied. Photon correlation spectroscopy experiments on polyaniline dispersions are considered to indicate the presence of elongated structures (Figure). magnified image
Novel tellurium‐containing p‐terphenoquinone analogues: Preparation and unique redox properties of paramagnetic tellurium‐centered radical cation complexes
Authors: Tamura Rui , Nagata Yuya , Matsumoto Akira , Shimizu Hiroshi , Ono Noboru , Kamimura Akio , Hori Kenzi 
Published: May 2005

Amphoteric tellurium‐containing π‐donors'acceptors are reported. The electrical and magnetic properties of the charge‐transfer complexes and radical cation salts prepared from 1 (see Figure; X  Te, R1  Me) are presented. 1 exhibits a remarkably low oxidation potential compared with S analogues and a one‐step two‐electron reduction potential, indicating that its derivatives could also be of use as the first Te‐containing organic electron acceptors. magnified image
Mass sensitive detection of solvent vapors with calix[n]arenes—conformational adaptation to the analyte
Authors: Dickert Franz L. , Schuster Oliver 
Published: May 2005

Calixarenes have a hig molecular flexibility, facilitating an optimized adaptation to the shape of a large variety of guest molecules. Large substituents result in conformationally rigid compounds (Figure) but other calixarenes are ideal for coatings exhibiting high chemical sensitivity. magnified image
Conductiong polymer connections for molecular devices
Authors: Sailor Michael J. , Curtis Corrine L. 
Published: May 2005

Ways of connecting molecular devices will be needed if the ideas of molecular electronics are ever to be realized. The potential of conducting polymer nanowires for this purpose is discussed and illustrated with the case of poly(3‐alkylthiophene), which can be made to connect two Pt wires by forming dendrites between them (see Figure). magnified image
CVD of Covalent Compounds and high‐Tcsuperconductors
Authors: Gómez‐Aleixandre Cristina , Sanchez Olga , Albella José M. , Santiso José , Figueras Albert 
Published: May 2005

Chemical vapor deposition at high temperaturesprovided the deposited atoms with the necessary surface mobility to ensure crystallinity and epitaxial growth. The use of high‐temperaure CVD in the deposition of high‐Tcsuperconducting ceramics and covalent materials such as diamond (see Figure) and boron nitride is reviewed, and, for example, the methods used to maintain the terahedral arrangement of neighboring atoms during deposition discussed.magnified image
Second harmonic generation in ferroelectric liquid crystalline thiadiazole derivatives
Authors: Loos‐Wildenauer Martina , Kunz Stefan , Voigt‐Martin Ingrid G. , Yakimanski Alexander , Wischerhoff Erik , Zentel Rudolf , Tschierske Carsten , Müller Meike 
Published: May 2005

Ferroelectric liquid crystals are of interest for applications in second order nonlinear optical experiments as they combine a thermodynamically stable polar structure with mobility. Low‐molecular weight‐(see Figure) and siloxane‐fixed FLCs are reportd which contain a donor‐acceptor π system in a heterocylic ring whic does not disturb the desired rod‐like shape of the molecules. magnified image
Microwave‐assisted synthesis of aluminum nitride
Authors: Ramesh Peelamedu D. , Rao Kalva J. 
Published: May 2005

Aluminum nitride is an important ad high‐cost ceramic materials used in the electronics industry due to its combination of thermal conductivity, high strength; low thermal expansivity, and low dielectric constant. A new, simple and attractive route to sbmicrometer AlN powder (see Figure) is reported based on the use of microwave radiation. magnified image
Porous etching: A means to enhance the photoresponse of indirect semiconductors
Authors: Erné Ben H. , Vanmaekelbergh Daniël , Kelly John J. 
Published: May 2005

A strategy for improving the photoresponse for junctions based on crystalline and polycrystalline semiconductors is presented. Porous etching is used to produce a layer (e.g., see Figure) within which the light is more effectively absorbed. By tailoring the porous layer, it is possible to ensure that the minority carriers, while generated deep within the semiconductor, are nevertheless able to reach the junction without recombining magnified image.
Single crystal ß‐Si3N4 fibers obtained by self‐propagating high temperature synthesis**
Authors: Rodriguez Miguel A. , Makhonin Nikolay S. , Escriña Juan A. , Borovinskava Inna P. , Osendi María I. , Barba Maria F. , Iglesias Juan E. , Moya José S. 
Published: May 2005

The growth of single crystal β‐silicon nitride fibers (see Figure) several millimeters long through the application of self‐propagating high‐temperature synthesis is demonstrated. Advantages include the igh purity of the fibers obtained, the fact that the fibers are stable up to 2000°C, and the low cost of the SHS process magnified image.
Precursor‐derived Covalent Ceramics*
Authors: Bill Joachim , Aldinger Fritz 
Published: May 2005

The preparation of ceramic materials from preceramic compounds provides a means for the synthesis of new materials which cannot be obtained by conventional methods. An example is shown in the figure, which shows carbon‐fiber‐reinforced silicon carbide coated with silicon carbonitride prepared by dip‐coating the substrate with a slurry made of polyhydridomethylsilazane and silicon powder. Progress and applicational examples are reviewed magnified image.
Metamorphic materials: Restructuring siliceous mesoporous materials*
Authors: Khushalani Deepa , Kuperman Alex , Ozin Geoffrey A. , Tanaka Kaoru , Coombs Neil , Olken Michael M. , Garcés Juan 
Published: May 2005

Effective tailoring of pore sizes in mesoporous molecular sieves (see Figure) has been achieved by a novel method involving the restructuring of the mesopores under mild aqueous conditions. A studyis reported aimed at elucidating the underlying chemistry. It is suggested that further investigation could provide insight into natural biomineral resorption and lead to materials with enhanced biocompatibility characteristics magnified image.
Liquid crystals based on 2‐fluoropyrimidine and ‐pyridine: synthesis, dielectric anisotropy and phase behavior*
Authors: Bremer Matthias 
Published: May 2005

Polar liquid crystals with strongly positive dielectric anisotropies are of continuing interest to the display industry because they help to lower both the operating voltage and the total power consumption of LCDs in portable devices. Fluorinated heterocyclic materials (Figure, right, where MG is a mesogenic group) are shown here to exhibit improved mesophase properties and higher dielectric anisotropies than commonly used materials based on carbocyclic structures (Figure, left) magnified image.
High‐spin alignment in π‐conjugated Polyradicals: A Magnetic polymer
Authors: Nishide Hiroyuki 
Published: May 2005

Extended dendritic, ladder, and cross‐linked polyradical frameworks empolying π‐conjugated backbones (e.g. see Fig.) show promise in the development of ferromagnetic polymers. Recent progress in this field is reviewed and the various classes of materials, for example polyacetylene‐, or polyphenylenevinylene‐based radicals, compared magnified image.
Synthesis and characterization of noble metal colloids in block copolymer micelles
Authors: Antonietti Markus , Wenz Eckhard , Bronstein Lyudmila , Seregina Mariana 
Published: May 2005

Noble metal nanoparticles have been used for more than 2000 years. Applications currently under discussion include solar cell technology, catalysis, and nonlinear optics, where the enormous interfacial surface area of the colloidally dispersed metals and their unique electronic properties resulting from size quantization are exploited. The problem of the stability of these materials has been addressed by using amphiphilic copolymer micelles (see figure) as a nanostructured stabilization environment for the metal particles magnified image.
Engineering macromolecules self‐assembly: Molecular tubes vs. protein sheets via single amino acid substitutions in E. coli glutamine synthetase
Authors: Dabrowski Michael J. , Atkins William M. 
Published: May 2005

Protein engineering provides a rationale for obtaining self‐assembling molecules which yield supramolecular arrays with varying quanternary architectures. An example is E. coli glutamine synthetase which can be manipulated to yield molecular tubes (see figure), cables, and hexagonally packed sheets magnified image.
Polymer films with a self‐organized honeycomb morphology
Authors: François Bernard , Pitois Olivier , François Jeanne 
Published: May 2005

Porous polymer films with a regular arrangement of pores (see figure) with a narrow pore size distribution have recently been reported. The preparation of the films from a variety of star polystyrenes, micellar polystyrenes, and block copolymers, the mechanism of formation, and the potential applications of the materials are presented magnified image.
Self‐Assembling Frameworks: Beyond microporous oxides
Authors: Bowes Carol L. , Ozin Geoffrey A. 
Published: May 2005

The self‐assembly of inorganic open framework structureshas blossomed during the 1990s. Following a short historical summary of the field, the main features of the major classes of microporous materials—cyanide open‐frameworks, chalcogenides, polychalcogenides and thio‐pnictates—are described. The Review concludes with a brief discussion of microporous structures of the main group (e.g. K8Sn25, see figure) and organic tecton frameworks.magnified image
Hydrogen‐bonded pseudopolyrotaxanes
Authors: Asakawa Masumi , Ashton Peter R. , Hayes Wayne , Stoddart J. Fraser , Brown George R. , Menzer Stephan , White Andrew J. P. , Williams David J. 
Published: May 2005

That supramolecular order on the nanometer scale in the crystalline state can be created by using both π–π stacking and hydrogen bonding interactions marks a significant development in the fields of crystal engineering and supramolecular chemistry. The design and construction of pseudorotaxane monomers (see figure) via self‐assembly is described, which are then further assembled to form linear pseudopolyrotaxane columns. magnified image
Field‐effect transistor made with a sexithiophene single crystal
Authors: Horowitz Gilles , Garnier Francis , Yassar Abderrahim , Hajlaoui Riadh , Kouki Fayçal 
Published: May 2005

For the fabrication of organic transistors sexithiophene (6T) is one of the most promising materials. Since high purity improves the transistor performance of 6T, the FET described here was built on an ultrapure sexithiophene single crystal, shown in the figure as a gray block. The characteristics of this transistor—better than those of FETs based on evaporated polycrystalline sexithiophene—are presented. magnified image
Photorefractive Polymers and Composites
Authors: Zhang Yue , Burzynski Ryszard , Ghosal Saswati , Casstevens Martin K. 
Published: May 2005

AbstractMaterials demonstrating a photorefractive effect are principal candidates for numerous applications, including high‐density optical data storage, optical image processing, phase conjugated mirrors and lasers, dynamic holography, optical computing, pattern recognition, etc. Considerable progress has been made in the research on photorefractive polymers and composite materials in the last few years. These materials have many advantages over inorganic photorefractive crystals, including large optical nonlinearities, low dielectric constants, low cost and ease of fabrication. A large number of materials, including those exhibiting an extremely large photorefractive effect, have been developed. In addition, a number of interesting phenomena particular to polymeric photorefractive materials have been reported and corresponding mechanisms have been proposed to account for these phenomena. Possible applications of these materials have been explored with the demonstration of a volume holographic storage device based on photorefractive polymers. This paper reviews the latest developments of the young and exciting field of polymeric photorefractive materials.
Cathodic electrodeposition from aqueous solution of dense or open‐structured zinc oxide films
Authors: Peulon Sophie , Lincot Daniel 
Published: May 2005

Direct electrodeposition of zinc oxide films is reported for the first time. That this method of preparation is suited to large‐scale production could be important for applications of ZnO, e.g., in solar cells. In addition to a description of the preparation and properties of the films, it is shown that the morphology of the layer can be controlled, varying from compact to open (see figure) structures. magnified image
Dimeric Tetrathiafulvalenes: New electron donors
Authors: Otsubo Tetsuo , Aso Yoshio , Takimiya Kazuo 
Published: May 2005

Organic conductors based on new classes of dimeric TTFs (e.g., see figure) are reviewed. The complexes have structures in some cases which are determined by inter‐TTF transannular interactions, leading to stretched, folded, and sandwich arrangements. These multi‐TTF materials have potential applications in the development of molecular electronic devices based on multi‐stage redox systems. magnified image
Post‐polymerization functionalization of conducting polymers: Novel poly(alkylthiophene)s substituted with easily. Replaceable activated ester groups
Authors: Baüerle Peter , Hiller Markus , Scheib Stefan , Sokolowski Moritz , Umbach Eberhard 
Published: May 2005

One‐step post‐polymerization‐functionalization of polythiophene is reported. Using the new method presented here a large variety of amines carrying, for example, sterically demanding or electronically sensitive functional groups can be attached to conducting‐polymer‐modified electrodes even under aqueous conditions. The Figure shows the starting material which is polymerized then functionalized. The following paper in this issue presents the use of these materials in the development of amperometric biosensors. magnified image
Heterogenizing homogeneous catalysis
Authors: Petrucci Maria G. L. , Kakkar Ashok K. 
Published: May 2005

A new method for heterogenizing homogeneous catalysts involving simple acid–base hydrolytic chemistry on inorganic oxide surfaces is described. It provides easy access to thin films containing terminal amine and phosphine donor ligands, which are precursors to a variety of oriented organometallic surfaces (see figure; L =CO, PR3). Opportunities for the development of tailor‐made active and selective catalysts are discussed. magnified image
Gold nanoparticles in micellar poly(styrene)‐b‐poly(ethylene oxide) films—size and interparticle distance control in monoparticulate films
Authors: Möller Martin , Spatz Joachim P. , Roescher Arno 
Published: May 2005

Block copolymer micelles have been employed as nanosized reactors in which single gold particles were formed. Films can be produced by a process consisting of four steps. Monolayers of hexagonally assembled micelles (see Figure and this month's cover) can be prepared with rather regularly arranged, size‐controlled Au nanoparticles. The method of preparation and the factors influencing control of the process are presented. magnified image
Fabrication of single‐mode polymeric waveguides using micromolding in capillaries
Authors: Zhao Xiao‐Mei , Stoddart Alison , Smith Stephen P. , Kim Enoch , Xia Younan , Prentiss Mara , Whitesides George M. 
Published: May 2005

Micromolding in capillaries (MIMIC) has been used to fabricate arrays of single‐mode polymeric waveguides from several classes of polymeric materials (epoxies, polyrethanes, and polyacrylates) supported on Si/SiO2 substrates. Waveguides clad with polymers having slightly lower refractive indices gave single‐mode output in the visible and near‐infrared regions. A typical waveguide structure exhibiting single‐mode behavior is shown in the Figure. magnified image