Eric Giglio

Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP) | CIMAP

In nano-capillaries of large aspect ratio, the attractive image charge force is strong enough to affect the trajectory of ions passing through capillaries and consequently to diminish the fraction of transmitted beam ions. We calculated the theoretically transmitted fraction, using an approached but CPU-friendly expression of the image charge force...

In nanocapillaries of large aspect ratio, the attractive image charge force is strong enough to affect the trajectory of ions passing through capillaries and consequently to diminish the fraction of transmitted beam ions. We calculated the theoretically transmitted fraction, using an expression of the image charge force valid in the case of a stati...

Experimental data are presented for low-energy singly charged ion transport between two insulating parallel plates. Using a beam intensity of approximately 20 pA, measurements of the incoming and transmitted beams provide quantitative temporal information about the charge deposited on the plates and the guiding probability. Using a smaller beam int...

When an ion beam is injected into a tapered insulating capillary, the induced self-organized radial Coulomb potential in the capillary is able to focus the beam like an electrostatic lens. However, because of the continued accumulation of charge in the capillary, an equilibrium is rarely attained and the injected beam is eventually Coulomb blocked...

The transmission rate of a low-energy Arq+ ion beam through a macroscopic glass tube of large aspect ratio is simulated. Secondary electron (SE) emission, induced by ion impacts with the inner surface of the capillary, are taken explicitly into account by adding a SE source term to the charge dynamics equation. We find that the additional SE channe...

When an ion beam is injected into a tapered insulating capillary, the induced self-organized radial potential in the capillary is able to focus the beam like an electrostatic lens. However, because of the continued accumulation of charge in the capillary, an equilibrium is rarely attained and the injected beam is eventually "Coulomb" blocked by the...

In this work, we model and simulate the shape evolution of critically charged droplets, from the initial spherical shape to the charge emission and back to the spherical shape. The shape deformation is described using the viscous correction for viscous potential flow model, which is a potential flow approximation of the Navier-Stokes equation for i...

In the first part, the experimental data, models and simulations of the droplet break-up of a critically charged droplet, from the initial spherical shape to the jet formation and back to the spherical shape are presented. The effect of the viscosity and charge mobility on the spontaneous shape deformation are highlighted using a potential flow mod...

Synopsis The transmission of a 1 keV Ar ⁺ beam between two glass plates was studied. We present experimental data with the goal to provide quantitative information about the buildup and decay of charge on the glass plates and how this correlates with the observed guiding.

Synopsis The transmission of 1 keV Ar ⁺ ions through a macroscopic glass capillary is simulated by taking explicitly into account the secondary electron (SE) emission generated by ion impacts inside the capillary. The SE emission re-distributes the injected charge in the capillary wall and thus modifies the guiding power of insulating capillaries....

Experimental observation of the dynamics of a micro-focused, 1 MeV proton beam guided through a single, insulating macrocapillary is presented. The micrometer sized proton beam was center injected into a poly(tetrafluoroethylene) capillary with macroscopic dimensions. The capillary was tilted to 1° with respect to the beam, i.e. no geometrical tran...

The dynamics of the charge distribution produced at the inner surface of an insulating capillary by low energy ion impact are investigated theoretically in the case where the entrance, exit and outer capillary surface are grounded. Starting with the surface continuity equation, that describes the charge dynamics at the inner surface, we deduced an...

We present a combined experimental and theoretical study of the transmission of single charged 1 keV Ar ions through a cylindrical glass capillary of macroscopic dimensions. From quantitative measurements of the incoming and transmitted ion currents, combined with a detailed analysis, the amount of beam entering the capillary was determined. This,...

Synopsis In a combined theoretical and experimental study, we give for the first time evidence that insulating tappered capillaries are able to focus the injected ion beam like an Einzel lens. We show that, under certain conditions, the self-organized axisymmetric Coulomb potential generated by the injected charges is strong enough to focus the ion...

The transmission of 1 keV Ar + ions through a macroscopic glass capillary is simulated by taking explicitly into account the secondary electron (SE) emission generated by ion impacts inside the capillary. The SE emission redistributes the injected charge in the capillary wall and thus modifies the guiding power of insulating capillaries. Especially...

In a combined theoretical and experimental study, we give evidence that the self-organized electric potential in tapered glass capillaries has the strength to focus a low-energy ion beam. Similar to Einzel lenses, the on-axis injected beam is focused by an axis-symmetric potential, generated by the charge accumulated in the insulating capillary. We...

Insulating glass capillaries have been shown to lead to ion transmission without any change in either the ion charge state or in the ion kinetic energy. This surprising process has been attributed to a self-organized distribution of charge patches creating the necessary guiding electric potential on the capillary walls. By the use of our original e...

An innovative experimental setup, PELIICAEN, allowing the modification of materials and the study of the effects induced by multiply charged ion beams at the nanoscale is presented. This ultra-high vacuum (below 5 × 10−10 mbar) apparatus is equipped with a focused ion beam column using multiply charged ions and a scanning electron microscope develo...

The transmission as a function of the tilt angle of a 3 keV Ar⁺ ion beam through a conical macroscopic glass capillary is studied theoretically and experimentally. It was found that the charge patches which are responsible for the ion guiding also compress the beam spatially in the direction orthogonal to the patches, resulting into an enhancement...

The discharge properties of a macroscopic cylindrically shaped glass capillary, initially charged by a 1 keV Ar⁺ beam tilted by 5° whith respect to the capillary axis is studied. Our experimental observations were compared to our Monte Carlo simulation, higlighting the importance of the surface conductivity.

Transmission of 1 keV single charged nitrogen ions through a macroscopic tapered borosilicate glass capillary is studied theoretically and experimentally. Measured time trend of the transmission for different low beam intensities are given. They are compared to realistic microscopic calculation that allows simulating the transmission of charged par...

We present a combined experimental and theoretical study of the fragmentation of HDO 2+ molecular ions produced by electron-impact ionization of HDO + in the collision energy range 20-2500 eV. Experimental absolute partial inclusive cross sections for the production of OD + , OH + , and O + are reported and compared successfully to theoretical pred...

We present a matrix functional form to fit the nearly degenerated potential energy surface of the H2O-OH molecular complex. The functional form is based on second order perturbation theory, which allows us to define two diabatic states coupled together in the field of the surrounding water molecules. The fit reproduces faithfully the fine details o...

The potential energy curves of the X, A, and B states of alkali-rare gas diatomic molecules, MKr and MXe, are investigated for M = Li, Na, K. The molecular spin-orbit coefficients a(R)=〈(2)Π(12)|Ĥ(SO)|(2)Π(12)〉 and b(R)=〈(2)Π(-12)|Ĥ(SO)|(2)Σ(12)〉 are calculated as a function the interatomic distance R. We show that a(R) increases and b(R) decreases...

We present a short review on recent theoretical studies of the dynamics of small Na clusters in contact with Ar matrices, in some cases also on NaCl surfaces. We discuss the hierarchical modeling which treats the cluster fully quantum-mechanically and the substrate at a classical level. The dynamical polarizability of the substrate is properly take...

We present a theoretical investigation of visible absorption and related luminescence of alkali atoms (Li, Na, and K) embedded in Ar matrix. We used a model based on core polarization pseudopotentials, which allows us to determine accurately the gas-to-matrix shifts of various trapping sites. The remarkable agreement between our calculated results...

Understanding of the molecular bond breakage selectivity, in order to control the bond cleavage, is one of the most exciting challenges in chemistry. The isotopomer of water HOD provides a three--atom prototype for studying such bond selectivity. A strong isotopic effect is evidenced in HOD^2+ ion fragmentation [1-2]. Moreover, the current interest...

We investigate the relaxation of photoexcited Li(2)(+) chromophores solvated in Ne(n) clusters (n = 2-22) by means of molecular dynamics with surface hopping. The simplicity of the electronic structure of these ideal systems is exploited to design an accurate and computationally efficient model. These systems present two series of conical intersect...

We present a theoretical investigation of the structure and optical absorption of M(2)(+) alkali dimers (M=Li,Na,K) solvated in Ne(n) clusters for n=1 to a few tens Ne atoms. For all these alkali, the lowest-energy isomers are obtained by aggregation of the first Ne atoms at the extremity of the alkali molecule. This particular geometry, common to...

We present non-adiabatic molecular dynamics simulations of size-selected Na2+ Arn (n=6-11-17) cluster. Their electronic structure is obtained from an accurate 1-electron model using core polarization pseudopotentials. We follow the dynamics of two specific photoexcitation processes (X2 Σ+g → A2Σ+u) and (X2 Σ+g → B2 Πu) during the first 10 ps. We id...

We present a detailed investigation of the ground and lowest excited states of M-Ne dimers, for M=Li, Na, and K. We show that the potential energy curves of these Van der Waals dimers can be obtained accurately by considering the alkali neon systems as one-electron systems. Following previous authors, the model describes the evolution of the alkali...

We present a detailed study of the potential energy surfaces (PES) of the semi-heavy water dication HOD2+ correlating asymptotically with O(3P) and O(1D). Using multi reference configuration interaction method, we generated a large set of data, which was used to fit the ground state and the first 7 excited PES for bending angles theta >= 80o and OH...

We present a non-adiabatic molecular dynamics simulation of a Na2+ molecule embedded in a single shell solvent made of 17 Ar atoms. The simulation is based on first principles calculation for 1-electron system combined with Tully surface hopping algorithm. The system is promoted to the first excited state and then followed during the first 10ps. Th...

We present a detailed study of the potential energy surfaces of the water dication correlating asymptotically with O((3)P) and O((1)D). Using ab initio multireference configuration interaction method, we computed a large ensemble of data, which was used to generate a fit of each potential energy surface for bending angles theta > or = 80 degrees de...

We present a theoretical study of Na2+ solvation in an argon matrix Arn for n = 1 to a few tens. We use a model based on an explicit description of valence electron interaction with Na+ and Ar cores by means of core polarization pseudopotential. The electronic structure determination is thus reduced to a one-electron problem, which can be handled e...

We present the deformation pathway of critically charged glycol and water droplets from the onset of the Rayleigh instability and compare it to numerical results, obtained for perfectly conducting inviscid droplets. In this simple model presented here, the time evolution of the droplet shape is given by the velocity potential equation. The Laplace...

Kinematically complete experiments lead to very substantial progress in the understanding of decay dynamics of multiply charged molecular ions. This paper is devoted to the study of dissociative ionization of water molecules and clusters induced by highly charged ions. We will present first how experimental results determined in the gas phase can p...

We present a kinematically complete study of dissociative ionization of D(2) by 13.6 MeV/u S(15+) ions. The experiment allows us to unravel the competing mechanisms, namely, direct single ionization, autoionization of doubly excited states, ionization excitation, and double ionization, and to analyze the corresponding electron angular distribution...

We present here a review of the experimental results obtained these last years at CIRIL laboratory in the field of swift heavy ion-induced small molecule fragmentation dynamics. Using the high ionizing power of highly charged ions, we study the formation and decay dynamics of charged molecules. We evidence the role of the excited states of the tran...

We present a theoretical study of Na3+ embedded in- and on the surface of a rare-gas droplet. We describe the active electrons of the cluster using time-dependent density functional theory, while the surrounding Ar atoms are treated by classical molecular dynamics of polarizable atoms. Like for neutral clusters, we found that the surrounding materi...

We present an effective numerical method to study the electronic and ionic dynamics of small atomic systems, like alkali-metal clusters. Our approach is based on the density functional theory (DFT) combined with molecular dynamics (MD). The time-dependent Kohn–Sham (KS) equations describing the electronic subsystem are solved self-consistently in t...

We investigate Na clusters embedded in Ar matrices. The surrounding Ar atoms are modeled in terms of their dynamical polarizability and the strong electron repulsion. The calibration of the model is discussed. First results for the non-linear optical response of the Na clusters are presented for the test case of Na8 embedded in Ar ensembles of diff...

We investigate fast, highly charged ion-induced HOD molecule fragmentation dynamics. Focusing on double ionization of the molecule, we evidence a strong preferential cleavage of the O-H bond rather than the O-D bond. We find an isotopic branching ratio defined as the number of H+ + OD+ over D+ + OH+ dissociations of 6.5 ± 0.5. Moreover, the coincid...

We investigate fast, highly charged ion-induced HOD molecule fragmentation dynamics. Focusing on double ionization of the molecule, we evidence a strong preferential cleavage of the O–H bond rather than the O–D bond. We find an isotopic branching ratio defined as the number of H+ + OD+ over D+ + OH+ dissociations of 6.5 ± 0.5. Moreover, the coincid...

We present a theoretical study of small sodium clusters embedded in a rare-gas matrix. We describe the active electrons of the embedded cluster using a time-dependent density-functional-theory method, while the surrounding polarizable atoms are treated by classical molecular dynamics. We study the spectroscopic properties of Na2 and Na8 embedded in...

We present a theoretical model to study the dynamics of metallic clusters embedded in a rare gas matrix. We describe the active electrons of the embedded cluster using time dependent density functional theory, while the surrounding matrix is described in terms of classical molecular dynamics of polarizable atoms. The coupling between the cluster an...

Several different time scales compete in metal clusters, Mie plasmon oscillations, Landau damping, electronic collisions, and ionic motion. It is the aim of this contribution to disentangle these using a palette of different dynamical observables: optical absorption, photo-electron spectroscopy (in energy and angular distributions), and pump-and-pr...

We present a semi-classical description of non-linear electron dynamics, able to take into account the dynamical correlations in form of an Ühling–Uhlenbeck collision term. These correlations should become important in the case of strongly excited dense electron systems, like a metal cluster irradiated by an intense femtosecond laser pulse. We show...

We present a theoretical study of the angular distribution of emitted electrons of a sodium cluster, irradiated by short and intense laser pulses. While the polarization of the excitation field tends to focus a directional emission, the dynamical correlations tend to thermalize the electrons, giving rise to a more isotropic ionization. The competit...

We present a selfconsistent semi-classical description of metal clusters with explicit ionic background. We show in particular how the flexibility of the Husimi picture allows a proper, self contained, description of ground state as well as dynamical properties of metal clusters. This leads to a coupled electrons + ions molecular dynamics, which ma...

We present a selfconsistent semi-classical description of metal clusters with explicit ionic background. We show in particular how the flexibility of the Husimi picture allows a proper, self contained, description of ground state as well as dynamical properties of metal clusters. This leads to a coupled electrons + ions molecular dynamics, which ma...

We present a selfconsistent semi‐classical description of metal clusters with explicit ionic background. We show in particular how the flexibility of the Husimi picture allows a proper, self contained, description of ground state as well as dynamical properties of metal clusters. This leads to a coupled electrons + ions molecular dynamics, which ma...

This work aims at studying the influence of electron-electron collisions on the electronic and ionic dynamics of metal clusters, excited by an intense femtosecond laser pulse. We use here a semi-classical description, which replaces the quantum wave-function, representing the the valence electrons of the metal cluster by a distribution function of...

We present an efficient way to evaluate the Ühling-Uhlenbeck (UU) collision term in the case of semi-classical dynamics. We focus on finite fermionic systems such as small metal clusters, which we recently pointed out the importance of the UU collision term for the electronic dynamics. We show, how far the hybrid method, which lies between the full...

A semiclassical treatment of electrons coupled to classical molecular dynamics of ions is presented. We consider real time dynamics for electrons at a Vlasov-LDA level and include dynamical correlations by an Ühling-Uhlenbeck collision term (VUU). Coupling to ionic motion is explicitly accounted for by means of a pseudopotential. The test case is t...

We present a non-adiabatic molecular dynamics description of metal clusters subject to violent perturbations. The electronic degrees of freedom are described at a semi-classical level, allowing an account of dynamical correlations, beyond the usual mean field density functional theory (DFT) scheme. Such an extended mean field allows to access highl...

We show that semiclassical methods provide a valid description for the electronic and ionic dynamical response of metal clusters in the regime of high excitation energies. We consider real time dynamics for electrons at a Vlasov-LDA level and include dynamical correlations by an Ühling-Uhlenbeck collision term. Coupling to ionic motion is explicitl...