Michel Broyer | Université Claude Bernard Lyon 1 (original) (raw)

Papers by Michel Broyer

Materials Science and Engineering: A, 1996

Since the last two decades, the physics of free clusters and assembled materials obtained from cl... more Since the last two decades, the physics of free clusters and assembled materials obtained from cluster deposition have opened a large field of potential applications [l]. Molecular dynamics simulations of the thin film growth by low energy cluster beam deposition (LECBD) show that impact energy (i.e. the initial free cluster energy) is the main characteristic parameter [2]. In the LECBD technique, the impact energy is low enough to have a "soft landing" process. Thus, the film grows by ballistic deposition of the free clusters if no rearrangement into clusters or coalescence between abutting supported clusters occurs. In the case of metallic clusters, small particles down to 2 nm diameter coalesce and the memory effect is destroyed [3] whereas covalent clusters present several features allowing the memory effect. Firstly, the covalent bond is highly oriented. Two abutting supported clusters can merge only if their own dangling bonds are in close direction. Secondly, the bond energy is high enough to avoid a large reconstruction because the break between two bonds cost appreciable energy. Thirdly, the equilibrium shape of the clusters present a large proportion of five-fold rings (see for example C,, having an & symmetry). Since the five-fold axis is not compatible with the translation symmetry, the film growth presents a large void component as in pure ballistic deposition. To study the specific properties of these new materials, we have deposited carbon and silicon clusters produced in a laser vaporization source. The properties of the films are studied using several techniques (Raman spectroscopy, XPS, EXAFS, etc.).

European Physical Journal D, 2003

The Editors of EPJ communicate the death of Gilbert Grynberg, who was serving in Section D as one... more The Editors of EPJ communicate the death of Gilbert Grynberg, who was serving in Section D as one of the Editors-in-Chief. Gilbert had been affected by a long illness, that he accepted with humour and style, avoiding to mention it or to refrain from his duties. We remember him as a fine scientist and a reliable friend, very active from the early days of our Journal, that we are proud to see appreciated in the international scientific community. We of EPJ D have asked two scientists who were very close to Gilbert's activity to provide the enclosed scientific biography.

Journal de Physique II, 1991

The Journal of Physical Chemistry A, 2017

It is demonstrated, using tandem mass spectrometry and radio-frequency ion-trap, that the adsorpt... more It is demonstrated, using tandem mass spectrometry and radio-frequency ion-trap, that the adsorption of a H atom on the gold dimer cation, Au2H + , prevents the dissociation of gold dimer cation and allows for adsorption of CO. Reaction kinetics are measured by employing a radio-frequency ion trap, where Au2 + and CO interact for a given reaction time. The effect of a hydrogen atom is evaluated by comparing reaction rate constants measured for Au2 + and Au2H +. The theoretical results for adsorption of CO molecules and their reaction characteristics with Au2 + and Au2H + are found to agree with the experimental findings. The joint investigations provide insights into hydrogen atom adsorption effects and consequent reaction mechanisms.

ACS nano, Dec 27, 2016

Homodimers of noble metal nanocubes form model plasmonic systems where the localized plasmon reso... more Homodimers of noble metal nanocubes form model plasmonic systems where the localized plasmon resonances sustained by each particle not only hybridize but also coexist with excitations of a different nature: surface plasmon polaritons confined within the Fabry-Perot cavity delimited by facing cube surfaces (i.e., gap plasmons). Destructive interference in the strong coupling between one of these highly localized modes and the highly radiating longitudinal dipolar plasmon of the dimer is responsible for the formation of a Fano resonance profile and the opening of a spectral window of anomalous transparency for the exciting light. We report on the clear experimental evidence of this effect in the case of 50 nm silver and 160 nm gold nanocube dimers studied by spatial modulation spectroscopy at the single particle level. A numerical study based on a plasmon mode analysis leads us to unambiguously identify the main cavity mode involved in this process and especially the major role played...

Physical Chemistry Chemical Physics, 2016

The generic optical absorption band of core–shell M@Ag nanoparticles observed in many experiments... more The generic optical absorption band of core–shell M@Ag nanoparticles observed in many experiments is rationalized through the formation of a Fano-like profile originating from the coupling between the silver shell LSPR and the core interband absorption continuum.

Physics and Chemistry of Small Clusters, 1987

The spectroscopy of Na3 has been systematically investigated with three different techniques: two... more The spectroscopy of Na3 has been systematically investigated with three different techniques: two-photon ionization (TPI), depletion spectroscopy (DS), and stimulated emission pumping (SEP). Four excited electronic states have been found in the range from 850 nm to 330 nm. The lifetime measurement of these states suggests that the highly excited ones are partially or totally predissociated. For this reason depletion spectroscopy has been used, and reveals the complete structure of the predissociated C-state. The Na3 ground state has been investigated using stimulated emission pumping. This allows a precise comparison with the calculations.

Physical Review B, 1993

Gallium clusters have been studied by near-threshold photoionization up to 2400 atoms. An electro... more Gallium clusters have been studied by near-threshold photoionization up to 2400 atoms. An electronic shell structure is clearly observed and may be interpreted by considering three electrons per atom. A quantum supershell corresponding to the interference between the contributions of triangular and square classical electronic orbits is obtained at about 2500 electrons. This number is considerably larger than expected from self-consistent homogeneous jellium calculations and is interpreted by introducing an inhomogeneous jellium approach.

Physik Journal, 2000

Various spectroscopic approaches to cluster physics are described, including Depletion Spectrosco... more Various spectroscopic approaches to cluster physics are described, including Depletion Spectroscopy, near Threshold Photoionization, Photofragmentation, Polarizability Measurements. These various methods allow to present some trends of the evolution of cluster properties from few atoms to the bulk.

Nanoscale, 2015

We show, both theoretically and empirically, that plasmonic coupling can be used to generate LSPR... more We show, both theoretically and empirically, that plasmonic coupling can be used to generate LSPRs in transition metal dimeric nano-antennas over a broad spectral range.

Rapid Communications in Mass Spectrometry, 2006

Collision-induced dissociation, laser-induced dissociation and electron-capture dissociation are ... more Collision-induced dissociation, laser-induced dissociation and electron-capture dissociation are compared on a singly and doubly protonated pentapeptide. The dissociation spectrum depends on the excitation mechanism and on the charge state of the peptide. The comparison of these results with the conformations obtained from Monte Carlo simulations suggests that the de-excitation mechanism following a laser or an electron-capture excitation is related to the initial geometry of the peptide.

Physical Review Letters, 1998

The competition between thermionic emission and direct photoelectron emission has been measured i... more The competition between thermionic emission and direct photoelectron emission has been measured in small tungsten clusters using photoelectron imaging spectroscopy. The kinetic energy distribution of electrons corresponding to thermionic emission is found to vary as p͑e͒~e 1͞2 exp͑2e͞kT͒, in agreement with theoretical predictions, and does not follow the bulklike function p͑e͒~e exp͑2e͞kT͒ or the simple exponentially decreasing Boltzmann function p͑e͒~exp͑2e͞kT͒, as usually assumed in photoelectron spectroscopy of clusters. Moreover, the angular distribution of direct photoelectrons is observed and the evolution as a function of the size is discussed. [S0031-9007(98)07082-3]

Physical Review A, 2001

Single-photon photodetachment of mass-selected W n Ϫ clusters has been studied by photoelectron i... more Single-photon photodetachment of mass-selected W n Ϫ clusters has been studied by photoelectron imaging spectroscopy. Velocity map imaging allows us to measure simultaneously the kinetic-energy spectrum and the angular distribution of photoelectrons. This provides a clear distinction between the two major decay mechanisms: isotropic thermionic emission and anisotropic direct photoemission. A careful study of threshold electrons shows that the thermal distribution cannot be described by a bulklike formula or a simple exponentially decreasing Boltzmann function. On the contrary, our results are in excellent agreement with more refined theoretical models taking into account the spherical symmetry of the cluster. The kinetic-energy distribution of thermal electrons corresponding to thermionic emission is found to vary as p(⑀)ϰ⑀ 1/2 exp(Ϫ⑀/k B T). Our results indicate that a transition toward a bulklike statistical behavior of the internal-energy redistribution occurs in very small systems owing to the high density of states in metal clusters. Moreover, the angular distribution of direct photoelectrons is obtained and the evolution as a function of size is discussed. The asymmetry parameter ␤ of the most intense band observed in direct photoemission for each cluster decreases monotonically with size: the direct photoemission of smaller systems is strongly anisotropic, becoming isotropic as the size of the system increases. This probably indicates the loss of coherence induced by electron-electron collisions occurring in large systems.

Physical Chemistry Chemical Physics, 2012

The Journal of Chemical Physics, 1998

The Journal of Chemical Physics, 1999

Le Journal de Physique IV, 1994

Zeitschrift f�r Physik D Atoms, Molecules and Clusters, 1993

ABSTRACT

Materials Science and Engineering: A, 1996

Since the last two decades, the physics of free clusters and assembled materials obtained from cl... more Since the last two decades, the physics of free clusters and assembled materials obtained from cluster deposition have opened a large field of potential applications [l]. Molecular dynamics simulations of the thin film growth by low energy cluster beam deposition (LECBD) show that impact energy (i.e. the initial free cluster energy) is the main characteristic parameter [2]. In the LECBD technique, the impact energy is low enough to have a "soft landing" process. Thus, the film grows by ballistic deposition of the free clusters if no rearrangement into clusters or coalescence between abutting supported clusters occurs. In the case of metallic clusters, small particles down to 2 nm diameter coalesce and the memory effect is destroyed [3] whereas covalent clusters present several features allowing the memory effect. Firstly, the covalent bond is highly oriented. Two abutting supported clusters can merge only if their own dangling bonds are in close direction. Secondly, the bond energy is high enough to avoid a large reconstruction because the break between two bonds cost appreciable energy. Thirdly, the equilibrium shape of the clusters present a large proportion of five-fold rings (see for example C,, having an & symmetry). Since the five-fold axis is not compatible with the translation symmetry, the film growth presents a large void component as in pure ballistic deposition. To study the specific properties of these new materials, we have deposited carbon and silicon clusters produced in a laser vaporization source. The properties of the films are studied using several techniques (Raman spectroscopy, XPS, EXAFS, etc.).

European Physical Journal D, 2003

The Editors of EPJ communicate the death of Gilbert Grynberg, who was serving in Section D as one... more The Editors of EPJ communicate the death of Gilbert Grynberg, who was serving in Section D as one of the Editors-in-Chief. Gilbert had been affected by a long illness, that he accepted with humour and style, avoiding to mention it or to refrain from his duties. We remember him as a fine scientist and a reliable friend, very active from the early days of our Journal, that we are proud to see appreciated in the international scientific community. We of EPJ D have asked two scientists who were very close to Gilbert's activity to provide the enclosed scientific biography.

Journal de Physique II, 1991

The Journal of Physical Chemistry A, 2017

It is demonstrated, using tandem mass spectrometry and radio-frequency ion-trap, that the adsorpt... more It is demonstrated, using tandem mass spectrometry and radio-frequency ion-trap, that the adsorption of a H atom on the gold dimer cation, Au2H + , prevents the dissociation of gold dimer cation and allows for adsorption of CO. Reaction kinetics are measured by employing a radio-frequency ion trap, where Au2 + and CO interact for a given reaction time. The effect of a hydrogen atom is evaluated by comparing reaction rate constants measured for Au2 + and Au2H +. The theoretical results for adsorption of CO molecules and their reaction characteristics with Au2 + and Au2H + are found to agree with the experimental findings. The joint investigations provide insights into hydrogen atom adsorption effects and consequent reaction mechanisms.

ACS nano, Dec 27, 2016

Homodimers of noble metal nanocubes form model plasmonic systems where the localized plasmon reso... more Homodimers of noble metal nanocubes form model plasmonic systems where the localized plasmon resonances sustained by each particle not only hybridize but also coexist with excitations of a different nature: surface plasmon polaritons confined within the Fabry-Perot cavity delimited by facing cube surfaces (i.e., gap plasmons). Destructive interference in the strong coupling between one of these highly localized modes and the highly radiating longitudinal dipolar plasmon of the dimer is responsible for the formation of a Fano resonance profile and the opening of a spectral window of anomalous transparency for the exciting light. We report on the clear experimental evidence of this effect in the case of 50 nm silver and 160 nm gold nanocube dimers studied by spatial modulation spectroscopy at the single particle level. A numerical study based on a plasmon mode analysis leads us to unambiguously identify the main cavity mode involved in this process and especially the major role played...

Physical Chemistry Chemical Physics, 2016

The generic optical absorption band of core–shell M@Ag nanoparticles observed in many experiments... more The generic optical absorption band of core–shell M@Ag nanoparticles observed in many experiments is rationalized through the formation of a Fano-like profile originating from the coupling between the silver shell LSPR and the core interband absorption continuum.

Physics and Chemistry of Small Clusters, 1987

The spectroscopy of Na3 has been systematically investigated with three different techniques: two... more The spectroscopy of Na3 has been systematically investigated with three different techniques: two-photon ionization (TPI), depletion spectroscopy (DS), and stimulated emission pumping (SEP). Four excited electronic states have been found in the range from 850 nm to 330 nm. The lifetime measurement of these states suggests that the highly excited ones are partially or totally predissociated. For this reason depletion spectroscopy has been used, and reveals the complete structure of the predissociated C-state. The Na3 ground state has been investigated using stimulated emission pumping. This allows a precise comparison with the calculations.

Physical Review B, 1993

Gallium clusters have been studied by near-threshold photoionization up to 2400 atoms. An electro... more Gallium clusters have been studied by near-threshold photoionization up to 2400 atoms. An electronic shell structure is clearly observed and may be interpreted by considering three electrons per atom. A quantum supershell corresponding to the interference between the contributions of triangular and square classical electronic orbits is obtained at about 2500 electrons. This number is considerably larger than expected from self-consistent homogeneous jellium calculations and is interpreted by introducing an inhomogeneous jellium approach.

Physik Journal, 2000

Various spectroscopic approaches to cluster physics are described, including Depletion Spectrosco... more Various spectroscopic approaches to cluster physics are described, including Depletion Spectroscopy, near Threshold Photoionization, Photofragmentation, Polarizability Measurements. These various methods allow to present some trends of the evolution of cluster properties from few atoms to the bulk.

Nanoscale, 2015

We show, both theoretically and empirically, that plasmonic coupling can be used to generate LSPR... more We show, both theoretically and empirically, that plasmonic coupling can be used to generate LSPRs in transition metal dimeric nano-antennas over a broad spectral range.

Rapid Communications in Mass Spectrometry, 2006

Collision-induced dissociation, laser-induced dissociation and electron-capture dissociation are ... more Collision-induced dissociation, laser-induced dissociation and electron-capture dissociation are compared on a singly and doubly protonated pentapeptide. The dissociation spectrum depends on the excitation mechanism and on the charge state of the peptide. The comparison of these results with the conformations obtained from Monte Carlo simulations suggests that the de-excitation mechanism following a laser or an electron-capture excitation is related to the initial geometry of the peptide.

Physical Review Letters, 1998

The competition between thermionic emission and direct photoelectron emission has been measured i... more The competition between thermionic emission and direct photoelectron emission has been measured in small tungsten clusters using photoelectron imaging spectroscopy. The kinetic energy distribution of electrons corresponding to thermionic emission is found to vary as p͑e͒~e 1͞2 exp͑2e͞kT͒, in agreement with theoretical predictions, and does not follow the bulklike function p͑e͒~e exp͑2e͞kT͒ or the simple exponentially decreasing Boltzmann function p͑e͒~exp͑2e͞kT͒, as usually assumed in photoelectron spectroscopy of clusters. Moreover, the angular distribution of direct photoelectrons is observed and the evolution as a function of the size is discussed. [S0031-9007(98)07082-3]

Physical Review A, 2001

Single-photon photodetachment of mass-selected W n Ϫ clusters has been studied by photoelectron i... more Single-photon photodetachment of mass-selected W n Ϫ clusters has been studied by photoelectron imaging spectroscopy. Velocity map imaging allows us to measure simultaneously the kinetic-energy spectrum and the angular distribution of photoelectrons. This provides a clear distinction between the two major decay mechanisms: isotropic thermionic emission and anisotropic direct photoemission. A careful study of threshold electrons shows that the thermal distribution cannot be described by a bulklike formula or a simple exponentially decreasing Boltzmann function. On the contrary, our results are in excellent agreement with more refined theoretical models taking into account the spherical symmetry of the cluster. The kinetic-energy distribution of thermal electrons corresponding to thermionic emission is found to vary as p(⑀)ϰ⑀ 1/2 exp(Ϫ⑀/k B T). Our results indicate that a transition toward a bulklike statistical behavior of the internal-energy redistribution occurs in very small systems owing to the high density of states in metal clusters. Moreover, the angular distribution of direct photoelectrons is obtained and the evolution as a function of size is discussed. The asymmetry parameter ␤ of the most intense band observed in direct photoemission for each cluster decreases monotonically with size: the direct photoemission of smaller systems is strongly anisotropic, becoming isotropic as the size of the system increases. This probably indicates the loss of coherence induced by electron-electron collisions occurring in large systems.

Physical Chemistry Chemical Physics, 2012

The Journal of Chemical Physics, 1998

The Journal of Chemical Physics, 1999

Le Journal de Physique IV, 1994

Zeitschrift f�r Physik D Atoms, Molecules and Clusters, 1993

ABSTRACT