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 Title: OBSERVATION OF HEAVY RYDBERG STATES IN H2 AND HD Author(s): Beyer, Maximilian Contributor(s): Merkt, Frederic Subject(s): Mini-symposium: Multiple Potential Energy Surfaces Abstract: The binding energies of the hydrogen atom are given by the Rydberg formula_x000d_ $$E_n = - frac{mathcal{R}_infty mu/m_e}{(n-delta)^2},$$_x000d_ where the quantum defect $delta$ vanishes in the case of a pure Coulomb potential. _x000d_ _x000d_ Heavy Rydberg systems can be realized when the electron is replaced by an anion, which leads in the case of H$^+$H$^-$ to an almost 1000 times larger Rydberg constant and to an infinite number of vibrational states._x000d_ In the diabatic molecular basis, these ion-pair states are described by long-range Coulomb potentials with $^1Sigma_g^+$ and $^1Sigma_u^+$ symmetry._x000d_ In this basis, the level energies are described by an almost energy-independent, nonzero quantum defect, reflecting the finite size of H$^-$. Strong interactions at small internuclear distances lead to strong variation of $delta$ with $n$._x000d_ _x000d_ Gerade [2] and ungerade [3] ion-pair states have been observed in H$_2$ with principal quantum numbers up to $n=240$. The quantum defects in this range were found to vary with energy, indicating the inadequacy of a pure diabatic picture._x000d_ _x000d_ Spectra of ungerade heavy Rydberg states of H$_2$ with $n=160-520$ showing that the quantum defect only becomes energy independent for $n>350$ will be presented, supporting the description using a diabatic basis._x000d_ _x000d_ I will also present first observations of ion-pair states in HD, showing two series of heavy Rydberg states, H$^+$D$^-$ and H$^-$D$^+$, which have different series limits._x000d_ The experimental results will be discussed and compared with calculations using both an adiabatic and a diabatic basis. _x000d_ _x000d_ _x000d_ [1] S. Pan, and F. H. Mies, textit{J. Chem. Phys.} textbf{89}, 3096 (1988)._x000d_ _x000d_ [2] M. O. Vieitez, T. I. Ivanov, E. Reinhold, C. A. de Lange, and W. Ubachs, textit{Phys. Rev. Lett.} textbf{101}, 163001 (2008)._x000d_ _x000d_ [3] R. C. Ekey, and E. F. McCormack, textit{Phys. Rev. A} textbf{84}, 020501(R) (2011)._x000d_ Issue Date: 6/19/2017 Publisher: International Symposium on Molecular Spectroscopy Citation Info: APS Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/96880 DOI: 10.15278/isms.2017.MG07 Date Available in IDEALS: 2017-07-27
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