Real-time dynamics of vibronic wavepackets within Rydberg and ion-pair states of molecular iodine

Jean-Michel Mestdagh (1) , Lou Barreau (2) , Lionel Poisson (2)

1 LIDYL - Laboratoire Interactions, Dynamiques et Lasers (ex SPAM)
2 ISMO - Institut des Sciences Moléculaires d'Orsay

Real-time dynamics of vibrationally and electronically excited I$_2$ molecules has been investigated experimentally using the pump–probe technique. A 2-photon excitation was performed either at 269 nm or 266 nm. An electronic and vibrational wavepacket was built as coherent superposition of a few (269 nm excitation) or many (266 nm excitation) Rydberg states of the [$^2$π$_3$$_/$$_2$]and [$^2$π$_1$$_/$$_2$]nd series partly coupled with ion-pair states. The probe operated by ionisation or photodetachement. The energy and angular distribution of the resulting photoelectrons, I$^+$ photocations and I$^-$ photoanions were monitored. During the dynamics that is turned on by the pump excitation, the wavepacket splits and explores a variety of electronic states of Rydberg and ion-pair character. The experimental results were complemented by molecular dynamics calculations. This provided invaluable information to identify wavepacket motion along ion-pair potential energy curves.

Domaines: Chimie théorique et/ou physique; Chimie-Physique [physics.chem-ph]

Jean-Michel Mestdagh, Lou Barreau, Lionel Poisson. Real-time dynamics of vibronic wavepackets within Rydberg and ion-pair states of molecular iodine. Physical Chemistry Chemical Physics, 2024, 26 (15), pp.11516-11530. ⟨10.1039/d4cp00118d⟩. ⟨hal-04554044⟩