Rb2

Rb2 is the diatomic molecule formed by two rubidium atoms. It occurs in the gas phase and in ultracold atomic experiments where rubidium atoms are cooled and trapped. The electronic ground state of the neutral rubidium dimer is typically denoted X1Σg+, with bonding arising from the relatively weak interactions characteristic of alkali metal dimers. The bond length of Rb2 is longer than many covalently bonded molecules, reflecting its weak bonding, and the dissociation energy is comparatively small.

Rb2 has been studied extensively through molecular spectroscopy, including electronic, vibrational, and rotational transitions. The spectroscopy of rubidium dimers provides detailed information about their potential energy curves and excited states. In nature and laboratory settings, the molecule exists in different isotopologue forms depending on the rubidium isotopes involved (for example, combinations of 85Rb and 87Rb), which can lead to slight shifts in spectral features.

In ultracold physics, Rb2 molecules are commonly produced from ultracold rubidium atoms via photoassociation or magnetoassociation near Feshbach resonances. These methods enable the creation of weakly bound molecules at near absolute zero temperatures, which are valuable for studies in controlled chemistry, quantum state engineering, and quantum simulation. The ability to form and manipulate Rb2 at ultracold temperatures makes it a useful system for testing molecular interaction models and exploring fundamental physics in a highly tunable environment.

Overall, Rb2 serves as a prototypical diatomic rubidium system, providing insights into alkali metal bonding, molecular spectroscopy, and ultracold molecular physics.