Giorgio Margaritondo

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Using the excellent performances of a SACLA (RIKEN/HARIMA, Japan) X-ray free electron laser (X-FEL), coherent diffraction imaging (CDI) was used to detect individual liposome particles in water, with or without inserted doxorubicin nanorods. This was possi ...

We investigated the adsorption properties of methanol and ethanol on Si(111)2 x 1 as a function of temperature in the range 80-300 K by means of synchrotron radiation photoemission of core and valence levels. A physisorbed state is characterized at 80 K, whereas at 300 K an alcohoxy species is formed. White-light exposures promote a decomposition reaction which leads to carbon on the Si surface, either on elemental form or as CH(x) groups.

Radiology is the oldest and by far the largest field of application of X-rays. In recent years, this domain has been literally revolutionized by the exploitation of the unique characteristics of synchrotron sources. The results are particularly spectacular when the high spatial coherence of the radiation is used for novel and powerful approaches to radiology. The results are very high quality microradiology and microtomograhy images and movies -taken with a limited X-ray dose- that find a variety of applica

High-resolution angle-resolved photoemission measurements were performed on single crystals of Bi2Sr2Ca1Cu2O8+delta with different oxygen stoichiometries. The data establish that the gap anisotropy (ratio of the gap along T-M to the gap along T-X) can be reversibly changed from similar to 20:1 (optimal or underdoped) to similar to 2:1 (overdoped). Differences in sample doping explain the conflicting reports on gap anisotropy in the literature. Possible effects of this change in gap anisotropy on the symmetr

Graphene nanoribbons were synthesized by oxidative unzipping of single-wall carbon nanotubes (SWCNTs). The nanoribbons produced from SWCNTs were characterized using FT-IR, Raman and X-ray photoelectron spectroscopy. For the morphological study of the produ ...

Infrared scanning near-field optical microscopy is used to detect AMPA-type glutamate receptor clusters in hippocampal neuron cells. AMPA's GluR2-subunits were marked with the fluorophore Alexa488 and high-resolution micrographs were taken at 6.25 µm wavel ...

Angle-resolved photoemission (ARPES) on the quasi-one-dimensional conductor (TaSe4)(2)I shows a hidden Fermi-surface crossing in its metallic state and the opening of a Peierls gap at low temperatures, The underlying quasiparticles have vanishing spectral weight and extremely short coherence lengths. They are interpreted as polarons in the strong-coupling adiabatic Lin-Lit, and almost all their ARPES weight is incoherent. These observations suggest a scenario where the long-standing contradictions between A

We explored the reactivity of gold on cleaved 2212 BiCaSrCuO by synchrotron-radiation photoemission spectroscopy. We found no evidence for reactivity when the substrate was at room temperature, similar to what has been reported for very low temperatures (20 K). At intermediate temperatures (100 K), however, clear evidence was found of a chemical reaction with formation of a localized nonmetallic phase. These findings have potentially important implications for the manufacturing of devices based on BiCaSrCuO

We report recent advances in hard-x-ray optics-including record spatial resolution-and in staining techniques that enable synchrotron microradiology to produce neurobiology images of quality comparable to electron and visible microscopy. In addition, micro ...

The fabrication of gold Fresnel zone plates, by a combination of e-beam lithography and electrodeposition, with a 30 nm outermost zone width and a 450 nm-thick structure is described. The e-beam lithography process was implemented with a careful evaluation ...

We analyzed photoemission data for several doping levels of the Bi2Sr2CaCu2O8+x compounds, ranging from overdoped to underdoped. We show that the high frequency part of the spectra near (0,pi) can be described by Fermi liquid theory in the overdoped regime, but exhibits a non-Fermi liquid behavior in the underdoped regime. We further demonstrate that this behavior fits reasonably well to a 1/root omega behavior suggested for systems with strong spin fluctuations. [S0163-1829(98)50338-4].

We identified the nature of the chemical reaction between silver and the cleaved surface of BiCaSrCuO at room temperature as a Bi-Ag reaction with Bi segregation, accompanied by interaction with the Sr atoms. Our synchrotron-radiation photoemission spectra also reveal an interaction of the adatoms with the O atoms, not detected by previous studies.

Utilizing a Mo-Si multilayer coated Schwarzschild objective to focus 95 eV photons, we have recently demonstrated better than 0.1 mum resolution as a scanning x-ray transmission microscope. Operating as a scanning photoemission microscope with submicron resolution, we have demonstrated its chemical mapping capabilities by studying a patterned Al/AlO(x) test structure. In addition, we have also studied the cleaved GaAs (110) surface and have identified lateral variations in the surface band bending on the sc

A method for detecting ink writings in a specimen comprising stacked pages, allowing a page-by-page reading without turning pages The method compris- es steps of taking a set of projection x-ray images for different positions of the specimen with respect t ...

We investigated the effect of disorder on the spectral properties of the high temperature superconductor Bi2Sr2CaCu2O8+x. We find that small defect densities, in the low 10(-3) range, already suppress the characteristic spectral signature of the superconducting state, while new excitations appear within the gap. We conclude that, due to defect-induced pair breaking, superconducting pairs and normal carriers coexist below T-c. At higher levels of disorder the normal state is also strongly affected, and the q

We report a study of the lateral band bending at the Ge-GaSe interface. Spectromicroscopy measurements with synchrotron radiation were performed at the ESCA microscopy line of ELETTRA in Ge patterned films on GaSe substrates. Preliminary results of lateral band bending, chemical reactions and the beam stimulated Ge surface migration are presented. These studies allowed us to seek on the microscopical equivalent of the semiconductor Debye length and to probe the capabilities of scanning-focused spectromicros

We investigated the effects of disorder in Bi2Sr2CaCu2O8+x high temperature superconductor. We found that small defect densities already suppress the characteristic spectral signature of the superconducting state. The spectral line shape clearly reflects new excitations within the gap, as expected for defect-induced pair breaking.

Using high energy resolution angle-resolved photoemission, we have measured both the superconducting gap and the photoemission superconducting condensate spectral area of Bi2Sr2Ca1Cu1O8+x as a function of temperature in two different locations of the Brillouin zone. We found that the size of superconducting gap along the Gamma - X direction decreases to values indistinguishable from zero for which the gap retains virtually full value along the Gamma - (M) over bar direction. The increased gap anisotropy wit

We explored a very interesting gold nanoparticle system-pegylated gold in colloidal solution-and analyzed its uptake by mice colorectal adenocarcinoma CT26 tumor cells and the impact on the cell's response to x-ray irradiation. We found that exposure to po ...

Valence- and conduction-band offsets can be induced at GaAs(100) polar homojunctions by means of ultrathin Si intralayers. The microscopic interface dipole responsible for the creation of such offsets can be varied by changing the Si intralayer thickness; the consequently variable band discontinuities represent a tunable parameter with potential applications in band-gap engineering. Even though the existence and the direction of these discontinuities are in agreement with theoretical predictions, the existi

Giorgio Margaritondo

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Free-electron-laser coherent diffraction images of individual drug-carrying liposome particles in solution

Chemisorption and Physisorption of Simple Alcohols on Cleaved Silicon

Synchrotron light in medical and materials science radiology

Doping-induced change of superconducting gap anisotropy in Bi2Sr2Ca1Cu2O8+delta

Graphene nanoribbons produced by the oxidative unzipping of single-wall carbon nanotubes

AMPA receptor imaging by infrared scanning near-field optical microscopy

Spectroscopic indications of polaronic carriers in the quasi-one-dimensional conductor (TaSe4)(2)I

Evidence for Surface Chemical-Reactions between Gold and Bicasrcuo

Nanoresolution radiology of neurons

Fabrication of high-aspect-ratio Fresnel zone plates by e-beam lithography and electroplating

Evolution of the quasiparticle spectral function in cuprates

Substitutional Reactions in the Surface-Chemistry of Bicasrcuo

1st Results of Microspectroscopy from a Scanning Photoemission Microscope with a Submicron Probe Size

Ancient administrative handwritten documents: virtual x-ray reading

Spectroscopic signatures of defect-induced pair breaking in Bi2Sr2CaCu2O8+x

Spectromicroscopy study of lateral band bending of the Ge-GaSe heterostructure

Defect-induced changes in the spectral properties of Bi2Sr2CaCu2O8+x: Angle-resolved photoemission study

Temperature-Dependence of the Superconducting Condensate and Gap in Bi2sr2ca1cu2o8+X

Enhanced x-ray irradiation-induced cancer cell damage by gold nanoparticles treated by a new synthesis method of polyethylene glycol modification

Artificial Band Discontinuities at GaAs Homojunctions