Welcome on My Personal webpage !
"I am a physicist who has a specific attraction for complex problems which require an experimental point of view to get new insights. This allows me to bring challenge and fun together!"
My impulse for research started during the graduation of my Bachelor's degree and Master'degree in "Science de la Matière" at the École Normale Supérieure of Lyon
(France) from 2009 to 2012.
Then this momentum continued during my PhD which I obtained from the University of Lyon
in October 2016.
My PhD work, entitled "Femtosecond and sub-femtosecond electron dynamics in super-excited complex molecular systems"
was performed at the Institut Lumière Matière
in the group Structure & Multi-Scales Dynamics of Complex Molecules
under the supervision of Dr. Franck Lépine
and Dr. Christian Bordas
It mostly consisted in studying the multielectronic effects and non-adiabatic mechanisms
in highly excited large molecules in gas phase.
Thus, I built an entire XUV-pump and IR-probe optical setup coupled to a Velocity Map Imaging spectrometer
enabling to measure the transient ion yield and electron momentum distribution from sevral species such as atoms/small molecules (e.g. He, Ar, N2
) or carboneous molecules (e.g. PAH, C60
) and biomolecules (e.g. cafeine, DNA basis).
During my PhD I could obtain expertise in time-resolved ultrafast spectroscopy
, out-of-equilibrium molecular physics
, femtosecond amplified laser
, high harmonic generation
, attosecond science
, electron/ion detection
and vacuum chamber desing for gas phase experiments
Then, I decided to move toward the condensed matter field in order to expand my general knowledge about ultrafast dynamics in the many-bodies quantum systems but also to start bridging the concepts of molecular physics with the one of condensed matter.
Thus, in December 2016, I started a post-doctorate at the University of Trieste
in the group of Prof. Daniele Fausti
(on the INCEPT project
whose laboratories are located in the synchrotron/FEL facility Elettra Sincrotrone S.C.P.A./FERMI
The aim of this post-doc research was to study out-of-equilibrium strongly correlated materials
and to show how to control their quantum matter phases
and their electronic properties through excitation of their low energy degrees of freedom.
Moreover, we were developing a full quantum state reconstruction of light pulses interacting with the out-of-equilibrium matter phases by measuring beyond the photon number mean value
, i.e. its fluctuations and spectral phase.
This new approach should provide richer statistical information than standard time-resolved spectroscopy techniques.
During my first post-doctorate experience, I could gain complementary expertise in strongly correlated materials
(cuprates, HTSC), mid-IR pulsed sources
(OPA, DFG), quantum optics
, cryostat engineering
Finally, I have recently joined the ERC-Synergy project NANOCOSMOS
, co-supervised by Dr. Christine Joblin
(group Milieu Interstellaire, Cycle de la Matière, Astro-Chimie
at the Institut de Recherche en Astrophysique et Planétologie
in order to study the photochemistry of PAH clusters under VUV irradation in link with their evolution in the photodissociation regions
Addressing the role of quantum coherence in the interplay between the different matter constituents (electrons, phonons and spin) is a critical step towards understanding transition metal oxides and design complex materials with new functionalities.
Here we use coherent vibrational control of onsite d-d electronic transitions in a model edge-sharing insulating transition metal oxide (CuGeO3) to single-out the effects of vibrational coherence in electron-phonon coupling.
By comparing time domain experiments based on high and low frequency ultrashort pumps with a fully quantum description of phonon assisted absorption, we could distinguish the processes associated to incoherent thermal lattice fluctuations from those driven by the coherent motion of the atoms.
In particular, while thermal fluctuation of the phonon bath uniformly increases the electronic absorption, the resonant excitation of phonon modes results also in light-induced transparency which is coherently controlled by the vibrational motion.
, S. Marcantoni, F. Giusti, F. Glerean, G. Sparapassi, T. Nova, A. Cartella, S. Latini, F. Valiera, A. Rubio, J. van den Brink, F. Benatti, and D. Fausti
Vibrational coherent control of localized d-d electronic excitation
We report here an experimental setup to perform three-pulse pump–probe measurements over a wide wavelength and temperature range.
By combining two pump pulses in the visible (650 nm–900 nm) and mid-IR (5 μm–20 μm) range, with a broadband supercontinuum white-light probe, our apparatus enables both the combined selective excitation of different material degrees of freedom and a full time-dependent reconstruction of the non-equilibrium dielectric function of the sample.
We describe here the optical setup, the cryogenic sample environment, and the custom-made acquisition electronics capable of referenced single-pulse detection of broadband spectra at the maximum repetition rate of 50 kHz, achieving a sensitivity of the order of 10−4 over an integration time of 1 s.
We demonstrate the performance of the setup by reporting data on a mid-IR pump, optical push, and broadband probe in a single crystal of Bi2Sr2Y0.08Ca0.92Cu2O8+δ across the superconducting and pseudogap phases.
A. Montanaro, F. Giusti, M. Colja, G. Brajnik, A. Marciniak
, R. Sergo, D. De Angelis, F. Glerean, G. Sparapassi, G. Jarc, S. Carracto, G. Cautero and D. Fausti.
Visible pump–mid infrared pump–broadband probe: Development and characterization of a three-pulse setup for single-shot ultrafast spectroscopy at 50 kHz
Unveiling and controlling the time evolution of the momentum and position of low energy excitations such as phonons, magnons, and electronic excitation is the key to attain coherently driven new functionalities of materials.
Here we report the implementation of femtosecond time- and frequency-resolved multimode heterodyne detection and show that it allows for independent measurement of the time evolution of the position and momentum of the atoms in coherent vibrational states in 𝛼-quartz.
The time dependence of the probe field quadratures reveals that their amplitude is maximally changed when the atoms have maximum momentum, while their phase encodes a different information and evolves proportionally to the instantaneous atomic positon.
We stress that this methodology, providing the mean to map both momentum and position in one optical observable, may be of relevance for both quantum information technologies and time-domain studies on complex materials.
F. Glerean, G. Jarc, A. Marciniak
, F. Giusti, G. Sparapassi, A. Montanaro, E. Maria Rigoni, J. Owen Tollerud, and D. Fausti.
Time-resolved multimode heterodyne detection for dissecting coherent states of matter
We have investigated photoionization delays in N2
by combining an extreme ultraviolet (XUV) attosecond pulse train generated by high harmonic generation (HHG) and a second harmonic femtosecond pulse with angularly resolved photoelectron spectroscopy.
While photoionization delay measurements are usually performed by using a standard XUV-infrared scheme, here we show that the present approach allows us to separate electronic states that otherwise would overlap, thus avoiding the spectral congestion found in most molecules.
We have found a relative delay between the X and A ionic molecular states as a function of the photon energy of up to 40 attoseconds, which is due to the presence of a shape resonance in the X channel.
This approach can be applied to other small quantum systems with few active electronic states.
V. Loriot, A. Marciniak
, S. Nandi, G. Karras, M. Hervé, E. Constant, E. Plésiat, A. Palacios, F. Martín and F. Lépine
High harmonic generation-2ω attosecond stereo-photoionization interferometry in N2
Start of my new post-doc position at the IRAP in the MICMAC group
in collaboration with Christine Joblin. I will experimentally study the photochemistry of nanograins in the interstellar condition.
One of the possible outcomes of time resolved techniques is the capability to control and, eventually, induce material properties on short (on the order of picoseconds or less) timescales through light pulses.
In this kind of experiments, a sample is perturbed suddenly by an ultrashort intense light pulse and then its effect on the material is studied as a function of the time passed from the excitation.
A good sample candidate to reach our scope is represented by cuprates, a class of materials characterized by Copper-Oxygen layers which determine their peculiar properties.
In particular, their rich phase diagram suggests that it is possible to reach a number of matter phases just by changing some parameters.
For example, below the so-called critical temperature our sample enters a superconducting phase.
In our work we observed that light pulses with certain properties (in particular regarding energy and polarization) can induce, for a very short time interval (1-2 ps) a superconducting response even above the critical temperature.
Experimental data are accompanied by a theoretical effective model, which justifies the enhancement of the superconducting response with an increase of coherence in the material. The hypothesis opens the possibility to change the thermodynamic constraints and to make quantum coherence feasible even at relatively high temperatures.
F. Giusti, A. Marciniak
, F. Randi, G. Sparapassi, F. Boschini, H. Eisaki, M. Greven, A. Damascelli, A. Avella, and D. Fausti.
Evidence of enhanced coherence in the superconducting state of optimally doped Bi2Sr2Y0.08Ca0.92Cu2O8+δ by midinfrared pulse excitation
The many-body quantum nature of molecules determines their static and dynamic properties, but remains the main obstacle in their accurate description.
Ultrashort extreme ultraviolet pulses offer a means to reveal molecular dynamics at ultrashort timescales.
Here, we report the use of time-resolved electron-momentum imaging combined with extreme ultraviolet attosecond pulses to study highly excited organic molecules.
We measure relaxation timescales that increase with the state energy.
High-level quantum calculations show these dynamics are intrinsic to the time-dependent many-body molecular wavefunction, in which multi-electronic and non-Born−Oppenheimer effects are fully entangled.
Hints of coherent vibronic dynamics, which persist despite the molecular complexity and high-energy excitation, are also observed.
These results offer opportunities to understand the molecular dynamics of highly excited species involved in radiation damage and astrochemistry, and the role of quantum mechanical effects in these contexts.
This is a study following the one of my first Nature Communication dealing with XUV induced dynamics in naphtalene but observed on the part of the slow two-color electrons
The story is still continuing in Lyon and that's great!
, V. Despré, V. Loriot, G. Karras, M. Hervé, L. Quintard, F. Catoire, C. Joblin, E. Constant, A. I. Kuleff & F. Lépine.
Electron correlation driven non-adiabatic relaxation in molecules excited by an ultrashort extreme ultraviolet pulse
Ultrafast XUV chemistry is offering new opportunities to decipher the complex dynamics taking place in highly excited molecular states and thus better understand fundamental natural phenomena as molecule formation in interstellar media.
We used ultrashort XUV light pulses to perform XUV pump–IR probe experiments in caffeine as a model of prebiotic molecule.
We observed a 40 fs decay of excited cationic states.
Guided by quantum calculations, this time scale is interpreted in terms of a nonadiabatic cascade through a large number of highly correlated states.
This shows that the correlation driven nonadiabatic relaxation seems to be a general process for highly excited states, which might impact our understanding of molecular processing in interstellar media.
Finally, 5 years after having performed the experiments in Milano, this nice study dealing with XUV induced dynamics in cafeine has been published.
Cafeine is good !
, K. Yamazaki, S. Maeda, M. Reduzzi, V. Despré, M. Hervé, M. Meziane, T. A. Niehaus, V. Loriot, A. I. Kuleff, B. Schindler, I. Compagnon, G. Sansone, and F. Lépine.
Ultrafast nonadiabatic cascade and subsequent photofragmentation of XUV excited caffeine molecule.