We have fabricated and tested single photon detectors based on a current biased superconducting niobium nanowire patterned into a meander. The detectors are fabricated from high quality, ultra high vacuum sputtered niobium thin films on a sapphire substrate. For detection of single optical photons, we show that the superconductor’s intrinsic kinetic inductance does not limit the reset time of t...

The DESY R&D program on cavities fabricated from large-grain niobium explores the potential of this material for the production of approximately 1000 nine-cell cavities for the European XFEL. The program investigates both basic material properties, comparing large grain material to standard sheet niobium, and material availability, production, and preparation aspects. Several single-cell caviti...

Electron energy loss spectra in conjunction with near-edge fine structures of purely stoichiometric niobium monoxide (NbO) and niobium pentoxide (Nb2O5) reference materials were recorded. The structures of the niobium oxide reference materials were checked by selected area electron diffraction to ensure a proper assignment of the fine structures. NbO and Nb2O5 show clearly different energy loss...

A series of niobium and tantalum imido complexes with mono-anionic ortho-metallated acetophenone imine ligands have been prepared and characterized using NMR spectroscopy, mass spectrometry and elemental analysis. These low symmetry complexes are produced with only one or two structural isomers in all cases and display interesting correlations between the steric bulk of the ligands employed and...

Transition metal oxides are considered as prototype models of reactions involving oxidative processes [1]. In this way, the detailed understanding of their electronic and molecular structure is of great interest in the prediction of their catalytic behavior and chemical reactivity toward inert organic molecules which are of industrial interest. In particular, it is possible to highlight the sel...

The far-infrared vibrational spectra for charged vanadium clusters as well as charged and neutral niobium clusters have been measured size specifically using farinfrared multiple photon dissociation. The ground state energy and vibrational spectra of a large number of stable and metastable structures for each of these sizes and systems have also been calculated using densityfunctional theory (D...

The study discusses the microstructure and mechanical properties of eight tested 0.3 % C -30 % Ni 18 % Cr cast steels stabilized with niobium and titanium after annealing in the cycle of 900 °C / 300 h. The niobium content in the cast steels varied from 0.0 to 2.0 % and that of titanium from 0.0 to 1.2 % by weight. Microstructure was examined using both light microscope and a scanning electron ...

Niobium and tantalum carbide clusters have been isolated in the gas phase and irradiated with intense tunable infrared (IR) light. Stable neutral clusters are selectively ionized and subsequently detected in a mass spectrometer. By tuning the IR frequency, infrared multiphoton absorption spectra are obtained for a whole range of clusters. These mass-selective IR spectra lead to insights into th...

A method to electropolish niobium with continuous current oscillation is introduced. The current continuously oscillates for as long as 3 hours. The key is to maintain continuous agitation of the acid mixture. A niobium surface treated by this method has suppressed grain boundaries and a lower hydrogen content. The method has been used to electropolish L-band half-cells. The test results of a 1...

Transient electrochemical techniques showed that in NaCI-KC1 melts the reduction of K2NbF7 occurs through a two-step reaction Nb(V) --> Nb(IV) --> Nb. When oxide ions were introduced, cyclic voltammetry indicated that the waves corresponding to reduction ol the complex NbF~progressively disappeared. Oxo complexes, such as NbOF~ n 3) , are reduced at a potential close to that of the Nb(IV) fluor...