Femtosecond two-photon photoassociation of hot magnesium atoms: A quantum dynamical study using thermal random phase wavefunctions

TL;DR

This study uses quantum dynamical methods to analyze femtosecond two-photon photoassociation of hot magnesium atoms, revealing how thermal ensembles and strong laser fields influence molecular formation.

Contribution

It introduces a quantum dynamical framework combining ab initio chemistry and thermal wavefunctions to model femtosecond photoassociation of hot atoms.

Findings

Random phase wavefunctions from eigenstates converge faster in yield calculations.

Non-perturbative modeling captures strong-field effects accurately.

Thermal ensemble effects are effectively incorporated into the dynamics.

Abstract

Two-photon photoassociation of hot magnesium atoms by femtosecond laser pulses, creating electronically excited magnesium dimer molecules, is studied from first principles, combining \textit{ab initio} quantum chemistry and molecular quantum dynamics. This theoretical framework allows for rationalizing the generation of molecular rovibrational coherence from thermally hot atoms [L. Rybak \textit{et al.}, Phys. Rev. Lett. {\bf 107}, 273001 (2011)]. Random phase thermal wave functions are employed to model the thermal ensemble of hot colliding atoms. Comparing two different choices of basis functions, random phase wavefunctions built from eigenstates are found to have the fastest convergence for the photoassociation yield. The interaction of the colliding atoms with a femtosecond laser pulse is modeled non-perturbatively to account for strong-field effects.