Формирование наноразмерных пленок золота в условиях многократного автооблучения при ионно-лучевом осаждении

Gold films with a thickness of several tens of nanometers were obtained on silicon and quartz substrates by ion-beam deposition – sputtering. It is shown that the predominant lateral growth of nanoscale metal layers along the substrate surface occurs under exposure to the high-energy component of the sputtered atoms flux. The decisive role in the nanometer gold film for-mation is played by the elastic collision of sputtered metal atoms with atoms of the substrate and the growing film. The application of the manifold deposition – sputtering operation allows sup-pressing the grain formation process and obtaining gold films with better characteristics than those with a single deposition.

Optical and Recombination Parameters of CdS1−xTex Thin Films Obtained by the CMBD Method

This paper presents the results of the photoacoustic, SEM, and surface photovoltage experiments performed on the series of CdS1−xTex thin films. These CdS1−xTex (0 ≤ x ≤ 1) thin films were obtained on the glass substrate by the chemical molecular beam deposition (CMBD) method. The polycrystalline character of these films was revealed by SEM pictures. From the experimental optical characteristics, the optical absorption coefficient spectra of the samples and values of their energy gaps vs. their composition were determined. From the surface photovoltage characteristics, the diffusion lengths of the carriers were also determined.

Low-energy electron holography imaging of conformational variability of single-antibody molecules from electrospray ion beam deposition

Imaging of proteins at the single-molecule level can reveal conformational variability, which is essential for the understanding of biomolecules. To this end, a biologically relevant state of the sample must be retained during both sample preparation and imaging. Native electrospray ionization (ESI) can transfer even the largest protein complexes into the gas phase while preserving their stoichiometry and overall shape. High-resolution imaging of protein structures following native ESI is thus of fundamental interest for establishing the relation between gas phase and solution structure. Taking advantage of low-energy electron holography’s (LEEH) unique capability of imaging individual proteins with subnanometer resolution, we investigate the conformational flexibility of Herceptin, a monoclonal IgG antibody, deposited by native electrospray mass-selected ion beam deposition (ES-IBD) on graphene. Images reconstructed from holograms reveal a large variety of conformers. Some of these conformations can be mapped to the crystallographic structure of IgG, while others suggest that a compact, gas-phase–related conformation, adopted by the molecules during ES-IBD, is retained. We can steer the ratio of those two types of conformations by changing the landing energy of the protein on the single-layer graphene surface. Overall, we show that LEEH can elucidate the conformational heterogeneity of inherently flexible proteins, exemplified here by IgG antibodies, and thereby distinguish gas-phase collapse from rearrangement on surfaces.

Создание равномерных покрытий импульсным лазерным осаждением

The present paper deals with the selection of laser beam processing parameters that guarantee the formation of thin coatings with even thickness by means of the laser beam deposition. Laser deposition was carried out in the atmosphere of Ar and Si and SiC samples were used as a source for the deposited material. Preliminary experiments show that there is a direct dependency between the brightness of the image of the deposited layer (at uniform illumination conditions) and its thickness. Therefore, it was possible to determine the thickness of the deposited layer for various processing parameters and to calculate the laws of motion of the work piece that guarantee the deposition of the layer with a minimal deviation of thickness from the required value. Calculated parameters were successfully used for the deposition of coatings on a substrate of a relatively large area.

Microstructure and Corrosion Resistance of AA4047/AA7075 Transition Zone Formed Using Electron Beam Wire-Feed Additive Manufacturing

A gradient transition zone was obtained using electron beam deposition from AA4047 wire on AA7075 substrate and characterized for microstructures, tensile strength and corrosion resistance. The microstructure of the transition zone was composed of aluminum alloy grains, Al/Si eutectics and Fe-rich and Si-rich particles. Such a microstructure provided strength comparable to that of AA7075-T42 substrate but more intense corrosion due to the higher amount of anodic Mg2Si particles. The as-deposited AA4047 zone formed above the transition zone was composed of aluminum alloy dendrites and interdendritic Al/Si eutectics with low mechanical strength and high corrosion potential.

Electron-beam deposition of thermoconducting ceramic coatings for microelectronic devices

This paper presents the experimental study of dielectric coatings based on aluminum oxide (Al2O3) and aluminum nitride (AlN) ceramics as applied to their use in microelectronics. It is shown that the coatings obtained by electron-beam evaporation of ceramic in forevacuum pressures (1-100 Pa) endow devices with required dielectric parameters and improves heat sink from the surface of monolithic integral circuits.

ON IMPROVING THE METHOD OF ELECTRON-BEAM DEPOSITION

The paper deals with improvement of the electron-beam additive forming of metal products using a vertically fed filler wire in vacuum with two electron beams as a heating source. We compared the importance of the power of the heat source required for fusing the layers with each other and the calculated power of the heat source required to melt the filler wire and the surface of the product. Within the experimental conditions of the multilayer electron beam deposition using side wire feeding, the electron beam power of 2.4 kW was required to ensure fusion without the defect formation between the layers during the deposition of Ti-6Al-4V titanium alloy. At the same time, approximate calculations of the minimum power of the heat source required to melt the filler wire and the surface of the product showed a level of 730 W.

Mass-selective and ice-free cryo-EM protein sample preparation via native electrospray ion-beam deposition

Electron cryomicroscopy (cryo-EM) and single-particle analysis (SPA) have revolutionized structure determination of homogeneous proteins. However, obtaining high-resolution structures from heterogeneous samples remains a major challenge, as the various protein states embedded in thin films of vitreous ice may be classified incorrectly, resulting in detrimental averaging of features. Here we present native electrospray ion-beam deposition (native ES-IBD) for the preparation of extremely high-purity cryo-EM samples, based on mass selection in vacuum. Folded protein ions are generated by native electrospray ionization, mass-filtered, and gently deposited on cryo-EM grids, and subsequently frozen in liquid nitrogen. We demonstrate homogeneous coverage of ice-free cryo-EM grids with mass-selected proteins and protein assemblies. SPA reveals that they remain structurally intact, but variations in secondary and tertiary structure are currently limiting information in 2D classes and 3D EM density maps. Our results show the potential of native ES-IBD to increase the scope and throughput of cryo-EM structure determination.

Navigate flying molecular elephants safely to the ground: mass-selective soft landing up to the Mega-Dalton range by Electrospray Controlled Ion-Beam Deposition

The prototype of a highly versatile and efficient preparative mass spectrometry system used for the deposition of molecules in ultra-high vacuum (UHV) is presented, along with encouraging performance data obtained on four model species which are thermolabile or not sublimable. The test panel comprises two small organic compounds, a protein, and a large DNA species covering a 4-log mass range up to 1.7 MDa as part of a broad spectrum of analyte species evaluated to date. Three designs of innovative ion guides, a novel digital mass-selective quadrupole (dQMS) and a standard electrospray ionization (ESI) source are combined to an integrated device, abbreviated Electrospray Controlled Ion Beam Deposition (ES-CIBD). Full control is achieved by i) the square-wave-driven radiofrequency (RF) ion guides with steadily tunable frequencies, including a dQMS allowing for investigation, purification and deposition of a virtually unlimited m/z range, ii) the adjustable landing energy of ions down to ~2 eV/z enabling integrity-preserving soft-landing, iii) the deposition in UHV with high ion beam intensity (up to 3 nA) limiting contaminations and deposition time, and iv) direct coverage control via the deposited charge. The maximum resolution of R=650 and overall efficiency up to T_total=4.4% calculated from solution to UHV deposition are remarkable as well, while the latter is mainly limited by the not yet optimized ionization performance. In the setup presented, a scanning tunneling microscope (STM) is attached for in situ UHV investigation of the deponents demonstrating a selective, structure-preserving process and atomically clean layers.