A5047406504- Advanced Chemical Physics Studies
- Laser-Matter Interactions and Applications
- Mass Spectrometry Techniques and Applications
- Atomic and Molecular Physics
- Spectroscopy and Quantum Chemical Studies
- Cold Atom Physics and Bose-Einstein Condensates
- Strong Light-Matter Interactions
- Quantum optics and atomic interactions
- Spectroscopy and Laser Applications
- Quantum Information and Cryptography
- Quantum, superfluid, helium dynamics
- Nuclear physics research studies
- Chemical Reactions and Isotopes
- Photochemistry and Electron Transfer Studies
- Advanced Fiber Laser Technologies
- Mechanical and Optical Resonators
- Laser-induced spectroscopy and plasma
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Catalytic Processes in Materials Science
- Quantum Electrodynamics and Casimir Effect
- Laser Design and Applications
- Rare-earth and actinide compounds
- Optical Polarization and Ellipsometry
- Quantum chaos and dynamical systems
Universidad de Antioquia
2012-2024
Universidad Autónoma de Madrid
2006-2010
We report experiments where hydrogen molecules were dissociatively ionized by an attosecond pulse train in the presence of a near-infrared field. Fragment ion yields from distinguishable ionization channels oscillate with period that is half optical cycle IR For aligned parallel to laser polarization axis, oscillations are reproduced two-electron quantum simulations, and can be explained terms interference between pathways involve different harmonic orders laser-induced coupling 1sσ(g)...
We used a split-mirror setup attached to reaction microscope at the free-electron laser in Hamburg (FLASH) perform an XUV-pump–XUV-probe experiment by tracing ultrafast nuclear wave-packet motion D2+(1sσg) with <10 fs time resolution. Comparison time-dependent calculations shows excellent agreement measured vibrational period of 22±4 D2+, points importance accurately knowing internuclear distance-dependent ionization probability, and paves way control sequential nonsequential two-photon...
We present a nonperturbative time-dependent theoretical method to study ${\mathrm{H}}_{2}$ ionization with femtosecond laser pulses when the photon energy is large enough populate ${Q}_{1}$ $(25--28\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ and ${Q}_{2}$ $(30--37\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ doubly excited autoionizing states. have investigated role of these states in dissociative analyzed, time domain, onset resonant peaks appearing proton kinetic distribution. Their dependence on...
Attosecond science, born at the beginning of this century with generation first bursts light durations shorter than a femtosecond, has opened way to look electron dynamics in atoms and molecules its natural timescale. Thus controlling chemical reactions electronic level or obtaining time-resolved images motion become goal for many physics chemistry laboratories all over world. The new experimental capabilities have spurred development sophisticated theoretical methods that can accurately...
The quantum photodynamics of a simple diatomic molecule with permanent dipole immersed within an optical cavity containing quantized radiation field is studied in detail. chosen under study, lithium fluoride (LiF), characterized by the presence avoided crossing between two lowest 1Σ potential energy curves (covalent-ionic diabatic crossing). Without field, after prompt excitation from ground state 1 1Σ, excited nuclear wave packet moves back and forth upper 2 state, but proximity crossing,...
We propose an experiment to find evidence of the formation light-induced crossings provoked by cavity quantum radiation on simple molecules using state-of-the-art optical cavities, molecular beams, pump-probe laser schemes, and velocity mapping detectors for fragmentation. The procedure is based prompt excitation subsequent dissociation in a three-state scheme polar diatomic molecule, with two $^{1}\mathrm{\ensuremath{\Sigma}}$ states (ground first excited) coupled UV pump then radiation,...
The fast dynamics of molecular polaritonics is scrutinized theoretically through the implementation two-dimensional spectroscopy protocols. We derive conceptually simple and computationally efficient formulas to calculate spectra for molecules, each them modeled as a system two electronic states including vibrational relaxation, immersed in an optical cavity, thus coupled quantized radiation. Cavity photon losses relaxation are incorporated into Hamiltonian form open quantum that solved...
Circular dichroism is a consequence of chirality. However, nonchiral molecules can also exhibit it when the measurement itself introduces chirality, e.g., measuring molecular-frame photoelectron angular distributions. The few such experiments performed on homonuclear diatomic show that, as expected, circular vanishes distributions are integrated over polar electron emission angle. Here we that this not case in resonant dissociative ionization H2 for photons 30-35 eV, which delayed from...
Two-photon double ionization (TPDI) of D2 is studied for 38-eV photons at the Free Electron Laser in Hamburg (FLASH). Based on model calculations, instantaneous and sequential absorption pathways are identified as separated peaks measured D++D+ fragment kinetic energy release (KER) spectra. The process appears high KER, corresponding to molecule's equilibrium distance, contrast mainly leading low-KER contributions. Measured angular distributions good agreement with theory.Received 12 August...
Shannon entropy and Fisher information calculated from one-particle density distributions von Neumann linear entropies (the latter two as measures of entanglement) computed the reduced matrix are analyzed for $^{1,3}S^{e},\phantom{\rule{4pt}{0ex}}^{1,3}P^{o}$, $^{1,3}D^{e}$ Rydberg series He doubly excited states below second ionization threshold. In contrast with entropy, we find that both entanglement able to discriminate low-energy resonances pertaining different $_{2}(K,T)_{{n}_{2}}^{A}$...
The photodetachment of the metastable ${\mathrm{He}}^{\ensuremath{-}}1s2s2p{}^{4}{P}^{o}$ state has been calculated in two photon energy regions interest: first, named here as region I, below double photoionization threshold ${\mathrm{He}}^{+}(n=1),$ involving outer-shell ionization and doubly excited states ${\mathrm{He}}^{\ensuremath{-}},$ second, II, above ${\mathrm{He}}^{\ensuremath{-}}$ $1s$ ${\mathrm{He}}^{+}(n=2)$ threshold, K-shell detachment triply a ``hollow ion.'' We have...
We address topics related to molecules coupled quantum radiation. The formalism of light–matter interaction is different for classical and fields, but some analogies remain, such as the formation light induced crossings. show that under particular circumstances, molecular dynamics or fields produce similar results, long radiation prepared a Fock state far from ultra-strong coupling regimes. At this point, choice specific initial states irrelevant since scales. However, in realistic...
Photoelectron angular distributions from fixed-in-space ${\text{H}}_{2}$ molecules exposed to ultrashort xuv laser pulses have been evaluated. The theoretical method is based on the solution of time-dependent Schr\"odinger equation in a basis stationary states that include all electronic and vibrational degrees freedom. Asymmetric are observed as consequence delayed ionization doubly excited states, which induces interferences between gerade ungerade channels. analysis this asymmetry...
We have implemented a method based on the Feshbach formalism along with an explicitly correlated configuration interaction to perform systematic study behavior of resonance parameters (energies and lifetimes) autoionizing states plasma-embedded He ${}^{1,3}{S}^{e}$, ${}^{1,3}{P}^{o}$, ${}^{1,3}{D}^{e}$, as function screening strength. In particular, we evolution lowest in series located below He${}^{+}$($N=2$) ionization threshold unscreened case. At variance one-electron atoms (where shape...
Atomic autoionization following photoabsorption is a typical example of quantum interferences governed by electron-electron correlation. Coherence between direct photoionization and paths results in "Fano profiles", widely explored atoms the last 60 years. The advent femto- attosecond laser technology made time-resolved images delayed electron ejection accessible, leading to reemergence such studies atomic systems. counterpart molecular phenomena show richness, as well complexity, added...
We have measured the production of both Lyα and Hα fluorescence from atomic H D for photodissociation H2 D2 by linearly polarized photons with energies between 24 60 eV. In this energy range, excited photofragments result primarily doubly molecular species which promptly autoionize or dissociate into two neutrals. Our data are compared ab initio calculations dissociation process, in state prompt ionization (non-resonant) channels considered. Agreement our experimental that earlier work,...
We study the photoionization and autoionization of helium atom subject to ultrashort laser pulses by using a Feshbach formalism in time domain. solve time-dependent Schrödinger equation terms configuration interaction (CI) spectral method, which total wavefunction is expanded with configurations defined within bound-like () scattering-like halfspaces. The method allows one provide accurate descriptions both atomic structure (energy positions widths) photodynamics. illustrate our approach (i)...
The K-shell photodetachment of the metastable ${1s2s2p}^{4}{P}^{o}$ ${\mathrm{He}}^{\ensuremath{-}}$ state is calculated ab initio with a complex scaled configuration interaction method in photon energy region between $\mathrm{He} 2s2p{}^{3}{P}^{o}$ threshold and second double ionization ${\mathrm{He}}^{+}$ $(n=2).$ Within this range triply excited states are reached they autoionize through electron detachment plus target excitation. only two related calculations reported so far from J. Xi...
A theoretical approach to obtain accurate values for autoionizing states parameters in Be-like systems is presented. The method based on the configuration-interaction expansion of two-active (outer) electron wavefunction terms correlated coordinates containing r12 explicitly and by including a model potential represent effect 1s2 core. Within our approach, 1snl core are removed from basis configurations using Phillips?Kleinman projection operator, resonance (energies widths) determined...
A theoretical study of two-photon ionization H2 by low-intensity ultrashort xuv laser pulses is reported. The method based on the solution time-dependent Schrodinger equation in a basis stationary molecular vibronic states which include all electronic and vibrational degrees freedom. In contrast with previous work, doubly excited states, also contribute to probabilities through autoionization, are explicitly included. We have found that, just below one-photon threshold, autoionization leads...
Applications of the Feshbach formalism to systems more than two active electrons are very scarce due practical limitations in construction projection operators $\mathcal{P}$ and $\mathcal{Q}$ that inherent theory. As a consequence, most previous applications rely on use approximate quasiprojection operators, whose theoretical justification is not yet clear. In this work, an implementation for three-electron atoms presented includes all ingredients original formalism. Energy positions...
We study the effect that a statically screened Coulomb potential represented by Debye-H\"uckel-Yukawa has in electronic structure of simplest molecule ${{\mathrm{H}}_{2}}^{+}$ within Born-Oppenheimer approximation. The method solution is based on two-center partial-wave expansion expressed confocal elliptic coordinates using B-spline polynomials. General algorithms for computation energies, wave functions, and dipole nonadiabatic radial matrix elements are given detail. As it occurs atoms,...
We compute the entanglement between electronic and vibrational motions in simplest molecular system, hydrogen ion, considering molecule as a bipartite electron motion. For that purpose we an accurate total non-Born-Oppenheimer wave function terms of huge expansion using nonorthogonal B-spline basis sets expand separately nuclear functions. According to Schmidt decomposition theorem for systems, widely used quantum-information theory, it is possible find much shorter but equivalent natural...