Giorgio Margaritondo

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The infrared (IR) absorption of a biological system can potentially report on fundamentally important microchemical properties. For example, molecular IR profiles are known to change during increases in metabolic flux, protein phosphorylation, or proteolytic cleavage. However, practical implementation of intracellular IR imaging has been problematic because the diffraction limit of conventional infrared microscopy results in low spatial resolution. We have overcome this limitation by using an IR spectroscop

We report on ah-plane resistivity (rho) and angle-reserved photoemission (ARPES) spectra for Bi2Sr2CaCu2O8+x single crystals irradiated with neutrons or electron-beam irradiation. Both the normal and superconducting states were measured with angle-resolved photoemission. Electron-beam irradiation leads to an increase in the residual resistivity, and a decrease in the superconducting transition temperature (T-c). The resistivity data does not indicate any pseudogap; the resistivity is linear from T-c to 300K

Monodisperse gold nanorods with high aspect ratio were synthesized by x-ray irradiation. Irradiation was first used to stimulate the creation of seeds. Afterward, nanorod growth was stimulated either by chemical reduction or again by x-ray irradiation. In ...

A simple imaging setup based on the principle of coherence-based contrast X-ray imaging with unmonochromatized synchrotron radiation was used for studying mammographic phantom and human breast specimens. The use of unmonochromatized synchrotron radiation s ...

The study of semiconductor interfaces and of solid interfaces in general requires novel instrument capable to investigate the lateral fluctuations of properties on a microscopic scale. We present the first result of a major effort in that framework, whose main objective is the exploitation of the unique characteristics of free electron laser (FEL) infrared sources. The background was provided by our previous development of FEL-based techniques to measure interface barriers with high accuracy and reliability

Heterojunction band lineups have been investigated for over 40 years, and still are one of the most difficult open problems in condensed matter research-with an immediate impact on heterojunction devices. Steady progress has been made at least in understanding the ingredients of the band lineup process since the advent of surface-sensitive techniques in this field. Empirical links with the problem of Schottky barriers were discovered, and for both cases ''extreme' models based on only one ingredient had to

We report on the ab-plane polarized reflectance of an untwinned (Bi1.57Pb0.43)Sr2CaCu2O8+delta single crystal over the frequency range from 80 to 32 000 cm(-1) (10 meV-4 eV) at temperatures between 10 and 300 K. We find a clear anisotropy in the ab-plane optical conductivity above and below T-c, which is very similar to that formerly published data of Bi2Sr2CaCu2O8 (M.A. Quijada et al., Z. Phys. B 94, 255 (1994)). We employ both the one-component and two-component analyses to the optical data, which suggest

We synthesized AuPt alloyed nanoparticles in colloidal solution by a one-pot procedure based on synchrotron x-ray irradiation in the presence of PEG (polyethylene glycol). The exclusive presence of alloyed nanoparticles with fcc structure was confirmed by ...

Can individual cells, including live cells, be imaged using hard x rays? Common wisdom until now required sophisticated staining techniques for this task. We show instead that individual cells and cell details can be detected in culture solution and tissues with no staining and no other contrast-enhancing preparation. The sample examined can be much thicker than for many other microscopy techniques without sacrificing the capability to resolve cells. The key factor in our approach is the use of a coherent s

Thin silicon dioxide films nitrided in N2O by rapid thermal processing (RTP) or in a classical furnace were investigated by x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and electrical measurements on metal-oxide-semiconductor capacitors. Differences between the two nitridation processes were observed and explained. In lightly nitrided films, nitrogen occupies two configurations. Nitrogen is bound to three silicon atoms with at least one in the substrate or all three in the oxide. In RT

Photoemission spectromicroscopy was used to investigate the electronic structure of TiO2 anatase single crystals and polycrystalline thin films. The stoichiometry and the degree of oxidation of as-grown crystals, as-deposited films, as well as of thermally annealed samples in different atmospheres, were analyzed, based on the Ti 2p and O 1s core levels, with an energy resolution of 0.4 eV. The experimental density of states (DOS) was found to be in agreement with the theoretical DOS reported in the literatu

Serpins, a superfamily of protease inhibitors, control proteolytic cascades in many physiological processes. Genomic studies have revealed the presence of a high number of serpin-encoding genes in Drosophila melanogaster, but their functions remain largely ...

Ion-bombarded polystyrene with a 0.5-keV Ar+ beam has been investigated by means of photoelectron spectroscopy performed with synchrotron radiation. After a dose of 10(15) ions/cm2 the evolution of the valence band of the bombarded sample towards an amorphous carbonlike configuration is reported. From the analysis of valence-band spectra we estimated the out-diffusion of hydrogen and showed that its electronic states remain well identified and stable until the hydrogen presence is about 35% with respect to

We report on a distortion of Bi2Sr2CanCun+1 O6+2n+x (n = 0,1) single crystals, perpendicular to the CuO2 planes (the c-axis), for non-stoichiometric samples containing an excess of Bi. The distortion involves two parts: (a) symmetric displacements in the SrO and CuO2 planes along the c-axis, and (b) an antisymmetric longitudinal compressive wave. The latter is revealed by observing odd harmonics in the X-ray diffraction (XRD) data. Such odd harmonics are typically extinguished for the 14/mmm space group of

The reaction of FePS3 single crystals with a 1.6M n-butyl lithium solution in n-hexane has been followed through de electrical conductivity measurements as a function of the intercalation time. In order to investigate the influence of lithium insertion on the FePS3 electronic properties we have also measured as a function of both temperature and intercalation time the de conductivity of equilibrated LixFePS3 single crystals. Upon lithium intercalation we have observed the following main effects: (i) an incr

Not fully grasping the concepts of relativity can lead to misunderstandings about the fundamental background of synchrotron emission. Here we deal with some intriguing cases, in which the relevant

speed of light' is not the invariant c but the speed with respect to a moving object. This specifically affects two pillars of synchrotron radiation: the Lorentz length contraction and the Doppler shift. We propose a teaching strategy relying on new versions of simple

thought' experiments. Besides putting synchr

The spatial distribution of X-ray synthesized, PEG coated Au nanoparticles in cancer-bearing mice and their time dependent accumulation were investigated with inductive coupled plasma - optical emission spectroscopy (ICP-OES), transmission electron microsc ...

Real-time X-ray microscopy was used to study the influence of hydrogen-bubble formation on the morphology of ramified zinc electrodeposit. The experimental results show that when intense hydrogen bubbling occurs at high potential, the morphology of the ram ...

We describe an approach for exploring microscopic properties of granular media that couples x-ray microtomography and distinct-element-method (DEM) simulations through image analysis. We illustrate it via the study of the intriguing phenomenon of instant a ...

A study of the formation of In- and Au-GaAs(100) interfaces is reported. The metal overlayers are deposited in ultrahigh vacuum on room-temperature (RT) and low-temperature (LT) (100)GaAs grown by molecular-beam epitaxy, following the evaporation of a protective As capping layer from the semiconductor surface. High-resolution photoemission spectroscopy and low-energy electron diffraction are used to characterize these interfaces. In forms a two-dimensional interface layer plus clusters at RT and LT, with re

Giorgio Margaritondo

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Chemically resolved imaging of biological cells and thin films by infrared scanning near-field optical microscopy

Disorder effects in cuprates

Tailored Au nanorods: optimizing functionality, controlling the aspect ratio and increasing biocompatibility

Comparison of unmonochromatized synchrotron radiation and conventional X-rays in the imaging of mammographic phantom and human breast specimens: A preliminary result

Interface applications of scanning near-field optical microscopy with a free electron laser

Heterojunction Band Discontinuities - a Fundamental Problem in Solid-State Science

Optical study of an untwinned (Bi1.57Pb0.43)Sr2CaCu2O8+delta single crystal: ab-plane anisotropy

One-pot synthesis of AuPt alloyed nanoparticles by intense x-ray irradiation

Imaging cells and tissues with refractive index radiology

Influence of nitrogen profile an electrical characteristics of furnace- or rapid thermally nitrided silicon dioxide films

Electronic-Structure of Anatase TiO2 Oxide

The serpin Spn5 is essential for wing expansion in Drosophila melanogaster

Valence-Band States of Ion-Bombarded Polystyrene

Periodic c-axis modulation and crystallographic Fourier analysis of Bi2Sr2Cun+1O6+2n+x (n=0,1) single crystals with excess Bi

Effects of lithium intercalation on the electronic properties of FePS3 single crystals

Teaching about the relativistic background of synchrotron radiation: some intriguing aspects with strong didactic implications

X-ray synthesized PEGylated (polyethylene glycol coated) gold nanoparticles in mice strongly accumulate in tumors

Hydrogen bubbles and the growth morphology of ramified zinc by electrodeposition

Coupled tomography and distinct-element-method approach to exploring the granular media microstructure in a jamming hourglass

Formation of Interfaces between In and Au and GaAs(100) Studied with Soft-X-Ray Photoemission Spectroscopy