Accurate time delay determination for femtosecond X-ray diffraction experiments

Intensity correlations and noise reduction are observed and characterized in the broadband supercontinuum generated by spatio-temporal solitons propagating in air, i.e., in filamentation of ultrashort laser pulses. Large correlations and reduction of the laser noise are observed already at the first steps of the filamentation process, while further propagation results in cascaded χ⁽³⁾ broadening processes and yield complex correlation maps. The spectral range yielding an optimal laser noise reduction of 3.6 dB is found to cover 10 nm around the fundamental wavelength. PACS 42.65.Jx; 42.65.Tg; 42.65.Ky; 42.50.Lc     

First Measurement of the Gerasimov-Drell-Hearn Sum Rule for 1H from 0.7 to 1.8 GeV at ELSA

To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] microb.     

Comparing results of X-ray diffraction, µ-Raman spectroscopy and neutron diffraction when identifying chemical phases in seized nuclear material,during a comparative nuclear forensics exercise

Journal of Radioanalytical and Nuclear Chemistry - This work presents the results for identification of chemical phases obtained by several laboratories as a part of an international nuclear...     

Über Chalkogenolate. 194 [1]: S-Bis(trimethylsilyl)aminoester von Dithiocarbamidsäuren 3. Kristall- und Molekülstruktur vom Methyl-und i-Propylderivat [1]

Inhaltsübersicht. Die Titelverbindungen R₂N–CS–S–N[Si(CH₃)₃]₂ mit Ii = CH₃ bzw. CH(CH₃)₂ kristallisieren orthorhombisch bzw. monoklin: Gitterkonstanten für R = CH₃ (bei ?165°C) a = 8,397(4) Å, b = 11,917(4) Å, c = 31,966 (11) Å, Pbca (Nr. 61), Z = 8. R = CH(CH₃)₂ (bei ?80°C) a =13,183(3) Å, b = 10,873(11) Å, c = 14,865(2) Å, β = 105,86(2)° P2₁/n (Nr. 14), Z = 4. Die Kristallstrukturen wurden unter Verwendung von 4227 bzw. 3 433 symmetrieunabhängigen Reflexen (gemessen bei ?165 bzw. ?80 °C) bestimmt und bis auf Zuverlässigkeitsfaktoren von R = 0,081 bzw. 0,082 verfeinert (R_w = 0,084 bzw. 0,114). Bei beiden Verbindungen ist der C₂N–CS–S–N-Teil des Moleküls nahezu planar. Zwischen dem Thiocarbonyl-S-Atom und dem N-Atom der silylierten Aminogruppe bestehen Wechselwirkungen. On Chalcogenolates. 194. S-Bis (trimethylsilyl) amino Esters of Dithiocarbamic Acids. 3. Crystal and Molecular Structure of the Methyl and i-Propyl Derivative The title compounds R₂N–CS–S–N[Si(CH₃)₃]₂ with R = CH₃ and CH(CH₃)₂, respectively, crystallize orthorhombic and monoclinic, resp.; cell dimensions and space group see “Inhaltsübersicht”. The structures of both compounds have been determined from single crystal X-ray data measured at ?165°C and ?80°C, resp., and refined to R's of 0.081 and 0.082, resp., (R_w = 0.084 and 0.114, resp.) using 4227 and 3433, resp., independent reflections. In both compounds the C₂N–CS–S–N core of the molecule is nearly plane. Between the thiocarbonyl sulfur atom and the nitrogen atom of the amino group interactions exist. In Fortführung unserer Untersuchungen [1, 2] über N, N-Dialkyldithiocarbamidsäure-S-bis(trimethylsilyl)aminoester R₂N–CS–S–N[Si(CH₃)₃]₂ haben wir die Kristall- und Molekülstrukturen der Verbindungen mit R = CH₃ und CH(CH₃)₂ bestimmt. Dabei sollte untersucht werden, welchen Einfluß sterisch anspruchsvollere Alkylgruppen (R = CH₃ → CH(CH₃)₂) auf die Molekülgeo-metrie haben. Eine strukturchemische Charakterisierung dieser Verbindungs-klasse ist bis jetzt noch nicht erfolgt; vgl. die Literaturzusammenstellung bei [3].     

Reaktion von Formamid mit Kohlenstoffdisulfid 2. Kristallstruktur von Kalium-N-formyldithiocarbamat [1]

On Chalcogenolates. 148. Reaction of Formamide with Carbon Disulfide. 2. Crystal Structure of Potassium N-Formyl Dithiocarbamate K[S₂C? NH? CO? H] crystallizes with Z = 16 in the monoclinic space group Cc with cell dimensions a = 13.187(13) Å, b = 12.928(3) Å, c = 13.962(6) Å, and β = 101.75 (3)°. The crystal structure has been determined from single crystal X-ray data measured at 20°C and refined to a conventional R of 0.034 for 1857 independent reflections (R_w = 0.038). The compound crystallizes by building a super-structure, which is based on an H-bridged 16-membered ring-system, formed by four[S₂C? NH? CO? H]^? anions. Two different binuclear K⁺ coordination polyhedra are formed with two oxygen and two sulfur atoms in common.     

Über Chalkogenolate. 163. Umsetzungen von Hydrazin mit Kohlenstoffdisulfid. 2. Kristallstruktur von Dikalium-1,2-hydrazin-bis(dithioformiat)

On Chalcogenolates. 163. Reactions of Hydrazine with Carbon Disulfide. 2. Crystal Structure of Dipotassium 1,2-Hydrazine-bis (dithioformate) The title compound K₂[S₂C? NH? NH? CS₂] ( 1 ) crystallizes with Z = 4 in the orthorhombic space group Pbna with cell dimensions a = 6.635(1), b = 10.825(2), c = 12.866(2) Å. The crystal structure has been determined from single crystal X-ray data measured at ?85 °C and refined to a conventional R of 0.034 for 969 independent reflections (R_w = 0.042). The [S₂C? NH? NH? CS₂]^2? ions are linked together by hydrogen bridges N? H…?S. The K⁺ ions are surrounded by seven sulfur atoms in irregular coordination.     

Synthesis and characterization of biocompatible and biodegradable polymers

New polyesters were synthesized using Krebs cycle acids. Poly(1, 4-butanediol dilactate succinate)(PBDS) and poly(1, 4-butanediol dilactate 2-acetoxy succinate)(PBDAS) were prepared by the polycondensation of 1, 4-butanediol dilactate with succinic anhydride and 2-acetoxy succinic acid, respectively. Poly(1, 4-butanediol succinate)(PBS) was also synthesized from 1, 4-butanediol and succinic anhydride. PBS/PBDS and PBS/PBDAS blends were prepared by the method of solvent casting. The effects of crystallization time and temperature onto melting behavior of PBS/PBDS and PBS/PBDAS blends were investigated by differential scanning calorimetry. The compatibility of each blend system was discussed using equilibrium melting point depressions. The biodegradation behavior was studied using PBS, PBDS, and PBDAS as the sole carbon source by Aspergillus niger. The molecular weights of the polymers which were obtained from GPC analysis decreased after degradation in five weeks.