Elucidating the roles of collision energy and photon momentum transfer in the formation of ultralong-range Rydberg molecules

TL;DR

This study investigates how collision energy and photon momentum transfer influence the formation and rotational distribution of ultralong-range Rydberg molecules, using spectroscopic measurements and a detailed theoretical model.

Contribution

It provides new insights into the roles of initial atom interactions, photon momentum, and temperature in Rydberg molecule formation, supported by experimental data and modeling.

Findings

Spectroscopic data matches model predictions including photon momentum effects.

Temperature influences the rotational distribution of Rydberg molecules.

Initial atom-atom interactions significantly affect molecular formation.

Abstract

Spectroscopic measurements of the rotational distribution of $^{84}$Sr and $^{86}$Sr 5sns $^1S_0$ ultralong-range Rydberg molecular dimers created via photoassociation in a cold gas are reported. The dimers are produced by two-photon excitation via the 5s5p $^1P_1$ intermediate state. The use of singlet states permits detailed study of the roles that the initial atom-atom interaction, photon momentum transfer during Rydberg excitation, and sample temperature play in determining the spectral lineshape and final dimer rotational distribution. The results are in good agreement with the predictions of a model that includes these effects. The present work further highlights the sensitivity of ultralong-range Rydberg molecule formation to the state of the initial cold gas.