Nanometric TiO 2 as NBBs for functional organic-inorganic hybrids with efficient interfacial charge transfer

International audienceThe purpose of this work is to establish a fabrication method for new electronic materials: organic-inorganic p-MAPTMS / titanium-oxo-alkoxy hybrids. The size-selected 5.2-nm TiO 2 nanoparticles (Nano Building Blocks-NBB) are generated in a sol-gel reactor with turbulent fluids micromixing. The surface exchange between propoxy and MAPTMS groups under vacuum pumping results in a stable nanoparticulate precursor available for 2-photon laser polymerisation. The hybrids demonstrate quantum yield of photoinduced charges separation 6 % and can steadily trap photoinduced electrons at number density of 6% Ti atoms. The materials are suitable for 3D-microstructuring

Ohmic and space-sнarge limited conductivity іn dihydrodibenzotetraaza[14]annulene thin films

The electrophysical properties of thermally deposited thin films of dihydrodibenzotetraaza[14]-annulene were investigated applying ohmic gold electrodes to them. The volt-ampere characteristic of planar thin films symmetric structure Au – dihydrodibenzotetraaza[14]annulene – Au under dark condition was measured. The direct current conductivity in this structure at room temperature and at a small applied voltage was ohmic, carried out by thermally generated carriers, and the conductivity, limited by space charges carried out by the injected carriers, was observed at a higher applied voltage. The transition from ohmic conductivity to conductivity limited by space charges occurred at an electric field strength in a thin film of Е ~ 4 × 10⁴ V/m.Исследовали электрофизические свойства термически нанесенных тонких пленок дигидродибензотетрааза[14]аннулена с использованием золотых омических контактов к ним. Измеряли темновую вольт-амперную характеристику планарной тонкопленочной структуры Au – дигидродибензотетрааза[ 14]аннулен – Au. Проводимость в этой структуре на постоянном токе при комнатной температуре и при небольшом приложенном напряжении была омической, осуществляемой термически генерированными носителями, а при более высоком приложенном напряжении наблюдалась проводимость, ограниченная пространственными зарядами, осуществляемая инжектированными носителями. Переход от омической проводимости к проводимости, ограниченной пространственными зарядами, происходил при напряженности электрического поля в тонкой пленке Е ~ 4 × 10⁴ В/м.Досліджували електрофізичні властивості нанесених термічним методом тонких плівок дигідродибензотетрааза[14]анулену з використанням золотих омічних контактів до них. Вимірювали темнову вольт-амперну характеристику планарної тонкоплівкової структури Au – дигідродибензотетрааза[14]анулен – Au. Провідність в цій структурі на постійному струмі при кімнатній температурі і невеликій прикладеній напрузі була омічною, що забезпечувалась термічно генерованими носіями, а при більш високій прикладеній напрузі спостерігали провідність, обмежену просторовими зарядами, що забезпечувалась інжектованими носіями. Перехід від омічної провідності до провідності, обмеженої просторовими зарядами, відбувався при напруженості електричного поля в плівці Е ~ 4 × 10⁴ В/м

Laser ablation loading of a radiofrequency ion trap

The production of ions via laser ablation for the loading of radiofrequency (RF) ion traps is investigated using a nitrogen laser with a maximum pulse energy of 0.17 mJ and a peak intensity of about 250 MW/cm^2. A time-of-flight mass spectrometer is used to measure the ion yield and the distribution of the charge states. Singly charged ions of elements that are presently considered for the use in optical clocks or quantum logic applications could be produced from metallic samples at a rate of the order of magnitude 10^5 ions per pulse. A linear Paul trap was loaded with Th+ ions produced by laser ablation. An overall ion production and trapping efficiency of 10^-7 to 10^-6 was attained. For ions injected individually, a dependence of the capture probability on the phase of the RF field has been predicted. In the experiment this was not observed, presumably because of collective effects within the ablation plume.Comment: submitted to Appl. Phys. B., special issue on ion trappin

New microorganism isolation techniques with emphasis on laser printing

The study of biodiversity, growth, development, and metabolism of cultivated microorganisms is an integral part of modern microbiological, biotechnological, and medical research. Such studies require the development of new methods of isolation, cultivation, manipulation, and study of individual bacterial cells and their consortia. To this end, in recent years, there has been an active development of different isolation and three-dimensional cell positioning methods. In this review, the optical tweezers, surface heterogeneous functionalization, multiphoton lithography, microfluidic techniques, and laser printing are reviewed. Laser printing is considered as one of the most promising techniques and is discussed in detail

Soft X-ray lasing with lithium ions ?

There are several experimental reports claiming to have demonstrated amplification and lasing at 13.5 nm on the Lyman–[MATH] transition in Li2+ ions produced by optical field ionization (OFI) of a preformed Li-plasma. We have systematically studied properties of Li-OFI-plasmas by recording simultaneously the time dependent XUV line emission and scattered femtosecond laser signals. Our investigations demonstrate that in the Li vapor (plasma) produced by nanosecond pulse laser ablation of a solid target clusters and microparticles are present that strongly influence the XUV emission. These observations raise doubts on the interpretation of so far reported results on the feasibility of the Lyman–[MATH] Li laser