Papers by Francesco Borghesani
Journal of Physics B: Atomic, Molecular and Optical Physics, 2007
We present an investigation of the Xe2 excimer emission spectrum observed in the near infrared ra... more We present an investigation of the Xe2 excimer emission spectrum observed in the near infrared range about 7800 cm -1 in pure Xe gas and in an Ar (90%) -Xe (10%) mixture and obtained by exciting the gas with energetic electrons. The Franck-Condon simulation of the spectrum shape suggests that emission stems from a bound-free molecular transition never studied before. The states involved are assigned as the bound (3)0 + u state with 6p [1/2]0 atomic limit and the dissociative (1)0 + g state with 6s [3/2]1 limit. Comparison with the spectrum simulated by using theoretical potentials shows that the dissociative one does not reproduce correctly the spectrum features.
Microwave signal generation based on the interaction of mode-locked laser pulses with a nonlinear optical crystal
Microwave Photonics (MWP) and the 2014 9th Asia-Pacific Microwave Photonics Conference (APMP) 2014 International Topical Meeting on, 2014
We report about a technique to generate microwave radiation by the irradiation of a nonlinear opt... more We report about a technique to generate microwave radiation by the irradiation of a nonlinear optical crystal with uniformly spaced, ultrashort optical pulses delivered by a mode-locked laser. By systematically studying the laser polarization and intensity dependence of the microwave signal it is possible to show that it is a nonlinear phenomenon and that it originates from optical rectification. We report in this work wide bandwidth detection of the generated microwave signals, achieved inside a coaxial copper structure.
A new analysis and new Molecular Dynamics (MD) simulations of the measurements of the mobility μ_... more A new analysis and new Molecular Dynamics (MD) simulations of the measurements of the mobility μ_i of O_2^- ions in dense supercritical Ar gas are reported. μ_i shows a marked dependence on the distance from the critical temperature T_c. A mobility defect appears as a function of the gas density and its maximum value occurs below the critical density. The locus of points of maximum mobility defect in the P-T plane appears on the extrapolation of the coexistence curve into the single-phase region. MD simulations quantitatively reproduce the mobility defect near T_c.
The excess electrons mobility μ has been measured recently in liquid mixtures of Kr and CH_4 as a... more The excess electrons mobility μ has been measured recently in liquid mixtures of Kr and CH_4 as a function of the electric field up to E≈ 10^4 V/cm and of the CH_4 concentration x up to x ≈ 10 temperatures T≈ 130 K, fairly close to the normal boiling point of Kr (T_b≈ 120 K)(folegani). We present here new data which extend the previous set in the region of low electric field. The experimental results are interpreted in terms of a kinetic model previously proposed to explain the concentration dependent behavior of μ in liquid Ar--Kr and Ar--Xe mixtures. The main result is that CH_4 is more effective in enhancing energy--transfer rather than momentum--transfer in comparison with mixtures of liquified noble gases. The field dependence of μ is quite complicate. In particular, at intermediate values of the field, there appears to be a crossover between two different electric--field dependent behaviors of μ. The electric field strength at crossover is well correlated with the concentratio...
We report measurements of excess electron mobility in dense Argon gas at the two temperatures $T=... more We report measurements of excess electron mobility in dense Argon gas at the two temperatures $T=152.15$ and 162.30 K, fairly close to the critical one ($T_c =150.7$ K), as a function of the gas density $N$ up to 14 atoms$\cdot$nm$^{-3}$ ($N_{c}=8.08$ atoms$\cdot$nm$^{-3}$). For the first time a maximum of the zero-field density-normalized mobility $\mu_{0}N$ has been observed at the same density where it was detected in liquid Argon under saturated vapor pressure conditions. The existence of the $\mu_{0}N$ maximum in the liquid is commonly attributed to electrons scattering off long-wavelength collective modes of the fluid, while for the low-density gas a density-modified kinetic model is valid. The presence of the $\mu_{0}N$ maximum also in the gas phase raises therefore the question whether the single scattering picture valid in the gas is valid even at liquid densities.
Excess electron mobility in high-density argon gas
Physical Review A, 1992
ABSTRACT
Journal of Electrostatics, 2001
We report measurements of excess electron mobility in dense Argon gas at the two temperatures T =... more We report measurements of excess electron mobility in dense Argon gas at the two temperatures T = 152.15 and 162.30 K, fairly close to the critical one (T c = 150.7 K), as a function of the gas density N up to 14 atoms•nm −3 (N c = 8.08 atoms•nm −3). For the first time a maximum of the zero-field density-normalized mobility µ 0 N has been observed at the same density where it was detected in liquid Argon under saturated vapor pressure conditions. The existence of the µ 0 N maximum in the liquid is commonly attributed to electrons scattering off long-wavelength collective modes of the fluid, while for the low-density gas a density-modified kinetic model is valid. The presence of the µ 0 N maximum also in the gas phase raises therefore the question whether the single scattering picture valid in the gas is valid even at liquid densities.
Electron mobility and localization effects in high-density Ne gas
Physical Review A, 1990
Page 1. PHYSICAL REVIEW A VOLUME 42, NUMBER 12 15 DECEMBER 1990 Electron mobility and localizatio... more Page 1. PHYSICAL REVIEW A VOLUME 42, NUMBER 12 15 DECEMBER 1990 Electron mobility and localization efFects in high-density Ne gas A. F.Borghesani and M. Santini Dipartimento di Fisica "Galileo Galilei, "Universita ...
The Journal of Chemical Physics, 2003
Electron mobility in high purity liquid CH4
Physics Letters A, 1991
We have measured the electron mobility in high purity liquid methane as a function of the tempera... more We have measured the electron mobility in high purity liquid methane as a function of the temperature in the range 92<=T<=122 K, using a pulsed photoemission technique. We have found a mobility 30 to 50% larger than most of the literature data. This discrepancy can be ascribed to the better gas purification method and to the measuring technique as well. Moreover, the mobility data agree fairly well with the Basak and Cohen theory assuming an electron effective mass m* smaller than the electron mass.
Undercut in a CF4Based High-Pressure Poly-Si Plasma Etch
Japanese Journal of Applied Physics, 1983
ABSTRACT
Electron swarm experiments in fluids-signal waveform analysis
Measurement Science and …, 1990
ABSTRACT
Zeitschrift Fur Naturforschung Section A-a Journal of Physical Sciences, 1986
An accurate determination of the "time-of-flight" in swarm experiments with a parallel plate drif... more An accurate determination of the "time-of-flight" in swarm experiments with a parallel plate drift chamber requires that the time evolution of the charge induced on the collector is linear. This is obtained in very large chambers where the edge effects can be neglected. However, the experimental conditions of high-mobility carriers and highly pressurized gases impose some constraints on the acceptable drift cell dimensions. We have numerically calculated the effects of the finite size of the collector by exploiting the methods of the images. The numerical results have been experimentally checked using a suitable drift cell of variable geometry. As a result, a quantitative limit on the ratio between the collector radius and the drift distance has been established in order to design drift cells for which the edge effects can be neglected.
Acta Physica Hungarica, 1987
The electron — atom scattering cross section in Ne is much smaller than that of other simple gase... more The electron — atom scattering cross section in Ne is much smaller than that of other simple gases. Therefore the electron mobility is field-dependent even for, very low fields. The zero-field electron mobility can be determined by extrapolation from μ(E) curves only.
International journal of …, 1995
We report measurements of the drift mobility of O −2 ions in dense He and Ne gas (in the temperat... more We report measurements of the drift mobility of O −2 ions in dense He and Ne gas (in the temperature range 45<T<330 K spanning a range of gas densities from dilute gas up to liquid values. Measurements have been carried out by means of the pulsed photoinjection technique. Ions are produced by resonant electron attachment to O2 impurities. In the low-density region the experimental results show a strong temperature dependence, in disagreement with the prediction of classical kinetic theory even though realistic interaction potentials are considered. On the other side of the density range, the ionic mobility in Ne seems to be explainable in terms of a hydrodynamic model including electrostriction effects.
A low-cost GPIB programmable precision voltage source
Review of Scientific Instruments, 1997
We have developed a simple, low-cost, GPIB programmable precision voltage source for laboratory u... more We have developed a simple, low-cost, GPIB programmable precision voltage source for laboratory use with two outputs in the range [0,−5] V and [0,+5]V. The original goal was to allow the interfacing to personal computer of older high-voltage sources that can be remotely driven by an analog signal. This voltage source can be more generally used whenever a GPIB programmable
A low-cost, continuously adjustable, high-voltage, regulated DC power supply
Measurement Science and Technology, 1990
ABSTRACT
A simple IEEE488 bus tester
Review of Scientific Instruments, 1995
We have developed a simple, low cost IEEE-488 bus tester useful as both a diagnostic instrument f... more We have developed a simple, low cost IEEE-488 bus tester useful as both a diagnostic instrument for interface troubleshooting and as a learning tool for a better understanding of the working principles of this interface system.
Electron attachment toO2molecules in dense helium and argon gases
Physical Review E, 1997
... 2137 ? 1997 The American Physical Society 2138 DINO NERI, AF BORGHESANI, AND M. SANTINI 56 Th... more ... 2137 ? 1997 The American Physical Society 2138 DINO NERI, AF BORGHESANI, AND M. SANTINI 56 The high-pressure cell can withstand pressures up to 10 MPa, can be cooled down to 25 K, and is ... Since RC 50 ms te , the electronic signal wave form is given by ve t vT 1 FIG ...
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Papers by Francesco Borghesani