The development of the techniques of Rydberg-Stark deceleration and multistage Zeeman deceleration have extended the range of cold molecules that can be generated by supersonic-beam deceleration methods. The talk will present recent applications of these methods to the study of fundamental properties of the few-electron molecules H2 and He2 and their molecular cations H2+ and He2+. In the case of molecular hydrogen, we use Rydberg-Stark deceleration and deflection on a curved chip to merge a beam containing cold Rydberg H2 molecules with a beam of ground-state H2 molecules and to vary the relative velocity of the two beams. In this way, we can study the reaction H2+ + H2 -&gt; H3+ + H at low collision energies (below kB * 1K) by exploiting the fact that the Rydberg electron does not affect the ion-molecule taking place within the Rydberg electron orbit. We also use cold samples of H2 molecules to carry out precision measurements of energy intervals in H2 and H2+ for comparison with the results of ab initio calculations. In the case of He2, we use multistage Zeeman deceleration to generate cold samples of spin-polarized He2 molecules in the a 3Σu+ metastable state (He2*). We then use coherent optical, microwave, and radiowave fields to measure rotational and spin-rotational intervals in He2* and He2+ with unprecedented accuracy. The talk will focus on recent results obtained in experiments on Rydberg states of H2 and He2 that combine the advantages offered by cold molecules and optical frequency combs.

Reaction dynamics and precision spectroscopy using cold samples of H2 and He2

255th National Meeting (2018)

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