M. Piacentini
Sapienza University of Rome
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by M. Piacentini.
Review of Scientific Instruments | 1995
A. Derossi; F. Lama; M. Piacentini; T. Prosperi; N. Zema
A dedicated beamline with a broad energy range of photons and with high flux and a high degree of circular polarization has been designed for the ELETTRA storage ring. The beamline exploits the circularly polarized radiation produced by an electromagnetic elliptical wiggler and cover the (5–1200) eV photon energy range using a double‐incidence spherical grating monochromator.
Journal of Physics: Condensed Matter | 1989
V. Grasso; F. Neri; S. Santangelo; L. Silipigni; M. Piacentini
Thermopower, conductivity and photoconductivity measurements as a function of temperature, from 130 to 320 degrees C, have been carried out on manganese thiophosphate, MnPS3. The transport mechanisms involved in distinct temperature ranges and under different illumination conditions have been identified. At 130 degrees C a dark conductivity value of 8.6*10-13 Omega -1 cm-1 has been measured, while photoconductivity values ranged from 8.8*10-13 to 6.1*10-8 Omega -1 cm-1. In particular, the dark conductivity process has been attributed to holes in the phosphorus 3pz valence band. The results have been interpreted on the basis of a model, already used for NiPS3, that assumes a weak, ionic, interaction between the transition-metal and the sulphur atoms. A possible energy distribution of both valence and conduction bands, together with Mn 3d levels, is also provided.
Il Nuovo Cimento D | 1991
V. Grasso; F. Neri; L. Silipigni; M. Piacentini
SummaryRoom temperature optical-reflectivity measurements on some transition metal thiophosphates were carried out in the near infrared and visible regions. The resulting spectra, interpreted on the basis of the «transition metal weakly interacting» model, agree well with earlier optical transmission measurements. Below the fundamental absorption edge, the observed features have been assigned to 3d–3d transitions occurring on the transition metal ion, while those observed at photon energies greater than the absorption threshold have been attributed to transitions from the valence bands to discrete 3d orbital levels or to the conduction bands. A more detailed information on the metal ion 3d levels energy distribution with respect to the valence band states belonging to the (P2S6)4- cluster and a more precise determination of the MPS3 absorption edge energy position have been obtained.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1994
F. Lama; A. Derossi; M. Piacentini; N. Zema
Abstract This paper describes the conceptual design of a bending magnet synchrotron radiation beamline based on a double-incidence plane grating monochromator. One of the bending magnets of the ELETTRA storage ring has been considered as a reference source assuming a beam energy of 1.5 GeV and a stored current of 400 mA. The monochromator covers the energy range from 6 eV to 200 eV, with three gratings (one in normal incidence and two in grazing incidence condition) achieving a resolving power of the order of 10 000 and delivering a photon flux of approximately 10 13 [photons/s/1% bandwidth]. The image dimensions onto the sample are 0.5 × 1 mm.
Il Nuovo Cimento D | 1994
A. C. Felici; N. Galbato; D. Debowska; T. Papa; M. Piacentini; F. Lama
SummaryWe have measured at room temperature the photoacoustic spectra of Cd1−xFexTe(0<x<0.055) around the CdTe fundamental absorption threshold. We identified an absorption band at (1.38±0.01) eV, increasing with the Fe concentration, that we assigned to the5E→3T1 transition within the Fe2+ (3d6) manifold. We observed also a broadening and a shift to higher energies of the CdTe absorption edge for increasingx.
Review of Scientific Instruments | 2006
A. Ustione; A. Cricenti; M. Piacentini; A. C. Felici
A new implementation of a shear-force microscope is described that uses a shear-force detection system to perform topographical imaging of large areas (∼1×1mm2). This implementation finds very interesting application in the study of archeological or artistic samples. Three dc motors are used to move a sample during a scan, allowing the probe tip to follow the surface and to face height differences of several tens of micrometers. This large-area topographical imaging mode exploits new subroutines that were added to the existing homemade software; these subroutines were created in Microsoft VISUAL BASIC 6.0 programming language. With this new feature our shear-force microscope can be used to study topographical details over large areas of archaeological samples in a nondestructive way. We show results detecting worn reliefs over a coin.
Physical Review B | 1988
F. Antonangeli; N. Zema; M. Piacentini; U. M. Grassano
Physical Review B | 1988
V. Grasso; F. Neri; S. Santangelo; L. Silipigni; M. Piacentini
Physical Review B | 1991
V. Grasso; F. Neri; P. Perillo; L. Silipigni; M. Piacentini
Physical Review B | 1990
V. Grasso; F. Neri; S. Patanè; L. Silipigni; M. Piacentini