Search results for "physics.atm-clus"
showing 8 items of 38 documents
Rotational echoes as a tool for investigating ultrafast collisional dynamics of molecules
2019
We show that recently discovered rotational echoes of molecules provide an efficient tool for studying collisional molecular dynamics in high-pressure gases. Our study demonstrates that rotational echoes enable the observation of extremely fast collisional dissipation, at timescales of the order of a few picoseconds, and possibly shorter. The decay of the rotational alignment echoes in ${\mathrm{CO}}_{2}$ gas and ${\mathrm{CO}}_{2}\text{\ensuremath{-}}\mathrm{He}$ mixture up to 50 bar was studied experimentally, delivering collision rates that are in good agreement with the theoretical expectations. The suggested measurement protocol may be used in other high-density media, and potentially …
Hall–Post inequalities: Review and application to molecules and tetraquarks
2019
A review is presented of the Hall–Post inequalities that give lower-bounds to the ground-state energy of quantum systems in terms of energies of smaller systems. New applications are given for systems experiencing both a static source and inner interactions, as well as for hydrogen-like molecules and for tetraquarks in some quark models. In the latter case, the Hall–Post inequalities constrain the possibility of deeply-bound exotic mesons below the threshold for dissociation into two quark–antiquark mesons. We also emphasize the usefulness of the Hall–Post bounds in terms of 3-body energies when some 2-body subsystems are ill defined or do not support any bound state.
Binding Sites, Vibrations and Spin-Lattice Relaxation Times in Europium(II)-Based Metallofullerene Spin Qubits.
2021
Abstract To design molecular spin qubits with enhanced quantum coherence, a control of the coupling between the local vibrations and the spin states is crucial, which could be realized in principle by engineering molecular structures via coordination chemistry. To this end, understanding the underlying structural factors that govern the spin relaxation is a central topic. Here, we report the investigation of the spin dynamics in a series of chemically designed europium(II)‐based endohedral metallofullerenes (EMFs). By introducing a unique structural difference, i. e. metal‐cage binding site, while keeping other molecular parameters constant between different complexes, these manifest the ke…
Simulating pump-probe photo-electron and absorption spectroscopy on the attosecond time-scale with time-dependent density-functional theory
2013
Molecular absorption and photoelectron spectra can be efficiently predicted with real-time time-dependent density functional theory. We show herein how these techniques can be easily extended to study time-resolved pump-probe experiments, in which a system response (absorption or electron emission) to a probe pulse is measured in an excited state. This simulation tool helps with the interpretation of fast-evolving attosecond time-resolved spectroscopic experiments, in which electronic motion must be followed at its natural timescale. We show how the extra degrees of freedom (pump-pulse duration, intensity, frequency, and time delay), which are absent in a conventional steady-state experimen…
MOLECULAR LINE-SHAPE MODELING FROM FIRST PRINCIPLES
2015
International audience; We present an ab initio approach to spectral line-shape modeling and the comparison of the results with experimental data.
Quasi-soliton spatial autoguidé en milieu non lineaire quadratique
2021
International audience; Nous démontrons ici des phénomènes d'autoguidage optique existant dans les milieux à non-linéarités quadratiques. En plus de la formation puis disparition d'un phénomène auto confiné, nous observons des effets de commutation ultrarapide et de démultiplication spatiale, ainsi qu'une restructuration temporelle suivie d'élargissements spectraux.
Echo-assisted impulsive alignment of room-temperature acetone molecules
2021
International audience; We experimentally and theoretically investigate the field-free alignment of the asymmetric-top acetone molecule. Our study shows that the production of postpulse aligned molecules in a dense sample (0.05-0.2 bar) of room-temperature acetone using a single-pulse excitation can be significantly improved by rotational alignment echoes induced in a two-pulse excitation scheme. We report the observation of fractional echoes that can be used to reveal the nonlinearity of the molecular system. In a proof-of-principle experiment, a pre-aligned sample of acetone is also used for third-harmonic generation. The analysis of the experimental data with numerical simulations based …
Modelling the effect of nuclear motion on the attosecond time-resolved photoelectron spectra of ethylene
2014
arXiv:1403.5408