Spectroscopy of Cold LiCa Molecules Formed on Helium Nanodroplets

Günter Krois, Johann Valentin Pototschnig, Florian Lackner*, Wolfgang Ernst*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We report on the formation of mixed alkali–alkaline earth molecules (LiCa) on helium nanodroplets and present a comprehensive experimental and theoretical study of the ground and excited states of LiCa. Resonance enhanced multiphoton ionization time-of-flight (REMPI-TOF) spectroscopy and laser induced fluorescence (LIF) spectroscopy were used for the experimental investigation of LiCa from 15000 to 25500 cm–1. The 42Σ+ and 32Π states show a vibrational structure accompanied by distinct phonon wings, which allows us to determine molecular parameters as well as to study the interaction of the molecule with the helium droplet. Higher excited states (42Π, 52Σ+, 52Π, and 62Σ+) are not vibrationally resolved and vibronic transitions start to overlap. The experimental spectrum is well reproduced by high-level ab initio calculations. By using a multireference configuration interaction (MRCI) approach, we calculated the 19 lowest lying potential energy curves (PECs) of the LiCa molecule. On the basis of these calculations, we could identify previously unobserved transitions. Our results demonstrate that the helium droplet isolation approach is a powerful method for the characterization of tailor-made alkali–alkaline earth molecules. In this way, important contributions can be made to the search for optimal pathways toward the creation of ultracold alkali–alkaline earth ground state molecules from the corresponding atomic species. Furthermore, a test for PECs calculated by ab initio methods is provided.
Original languageEnglish
Pages (from-to)13719-13731
JournalThe Journal of Physical Chemistry A
Issue number50
Publication statusPublished - 2013

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)
  • Theoretical
  • Experimental


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