1,721,019 research outputs found
Formation and distribution of compounds at the Ru - Si(001) ultrathin film interface
No full textInterface formation between Ru and Si(001) has been studied by x-ray and ultraviolet photoemissions. The film properties were investigated, for metal deposition at room temperature, as a function of the Ru film thickness and as a function of the annealing temperature of a thick grown film. From the evolution of the Ru and Si core levels, we find that alloying takes place at the interface during growth and estimate the thickness of the intermixed region to be of the order of 15–20 ML. Annealing at increasingly high temperatures causes the formation of different silicide phases, which are discussed in relation to theoretical and experimental data on related transition metal silicides
EUV soft X-ray characterization of a FEL multilayer optics damaged by multiple shot laser beam
No full textabstrac
Intramolecular and Intermolecular Rearrangements in Nanoconfined Polystyrene
No full textVacuum ultraviolet spectroscopy reveals an intramolecular rearrangement involving a change in "physical dimers" of adjacent pendant benzene rings of atactic polystyrene (aPS) from "oblique" to "head-to-tail" (ht) configuration in aPS films spin coated on fused quartz, as film thickness R goes below 4R g (R g = unperturbed polystyrene gyration radius ≈ 20.4 nm). Simultaneously, transverse layering of molecular "gyration spheres", for film thickness R ≤ 4R g, causes an increase in free energy (reduction in cohesion) that follows a (R g/R) h dependence with b ≈ 3, a clear deviation from planar confinement. The variation of in-plane and outof-plane cohesive energy over a film of a given thickness is explained by invoking a fixed-range, repulsive, modified Pöschl-Teller intermolecular potential, with the strength of this potential decreasing with increase in R. Possible reduction of "dimer" dipole moment due to ht configuration is consistent with reduction of cohesion between aPS molecular gyration spheres
Molecular states of polyacenes grown on noble metal surfaces
Full text linkHere we present a combined photoemission (UPS), metastable deexcitation (MDS) and optical absorption (NEXAFS) at C K-edge study of molecular states of polyacenes grown on Ag(111) and Au(111), from submonolayer to multilayer thicknesses. We focus on the evolution of the HOMO and LUMO molecular states induced by the adsorption from submonolayer to monolayer thickness and we find a different redistribution of these states in the various systems formed at RT: while a strong redistribution of the molecular states takes place in Pn/Ag(111) and Tc/Ag(111) interface, a weaker interaction is indicated for Tc/Au(111)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Gratings in a conical diffraction mounting for an extreme-ultraviolet time-delay-compensated monochromator
No full textThe conical diffraction mounting in which the direction of incident light belongs to a plane parallel to the direction of the grooves has the unique property of maintaining high diffraction efficiency, even in the extreme-ultraviolet (EUV) region. This property is useful for designing high-throughput time-delaycompensated monochromators for the spectral selection of ultrashort EUV pulses as the high-order harmonics generated by the interaction between an ultrashort laser pulse and a gas jet. The time compensation allows one to exploit the femtosecond scale duration of the harmonics both to have high intensity and to reach an unprecedented temporal resolution for pump and probe experiments. Because two gratings have to be used for time compensation, the high diffraction efficiency becomes an essential requirement, which can be fulfilled by the conical diffraction mounting. Measurements recently accomplished at the Bending Magnet for Emission Absorption and Reflectivity (BEAR) beam line (ELETTRA Synchrotron, Trieste, Italy) for three gratings in the 10-90 nm region are reported here that show a peak efficiency of as much as 0.7 in the first order. A model computing the electromagnetic propagation and the grating efficiency, implemented and tested with the experimental data, permits the study and design of rather complex systems operating in the conical mounting. Basic physical principles and mathematical aspects of the model are discussed here
EUV Polarimetry with single multilayer optical elementProceedings of SPIE
No full textA polarimetric measurement technique based on the analysis of the reflection data given by a single mirror rotated around the incidence beam axis is presented. In the extreme ultraviolet spectral region, a multilayer coated mirror must be used. The multilayer mirror must be fully characterized before the experiment. Theory demonstrates how this method allows complete determination of Stoke's parameters in case of a totally polarized beam. A simulation code has been developed in order to model the experiment in case of synchrotron radiation propagating in a bending magnet beamline and impinging a multilayer mirror. The simulation is useful to verify each time the effectiveness of the method in the different experimental conditions considered. Finally an experimental application is presented
Bonding and orientation of 1,4-benzenedimethanethiol on Au(111) prepared from solution and from gas phase
No full textThe orientation and bonding of 1,4-benzenedimethanethiol molecules on Au(111) is studied by means of x-ray and ultraviolet (UV) photoemission, xray absorption and metastable deexcitation spectroscopy. The organic films are prepared both from solution and by exposing the clean substrate to the vapours of the substance in an evacuated environment. This leads to two different growth modes: when self-assembled monolayers (SAMs) are prepared from solution, the molecules tend to form a bilayer film with the molecules standing upright and with the molecular axis forming an angle of about 30 degrees with respect to the substrate normal; when growth is carried out from the gas phase, the molecules tend to assume at the earliest stages of exposure a flat-lying configuration, with both sulfur end-groups bonding to Au; at increasing exposure the surface coverage presents a saturation and the chemisorbed molecules tend to assume an upright arrangement
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
