Two-photon pathway to ultracold ground state molecules of [superscript 23]Na [superscript 40]K
We report on high-resolution spectroscopy of ultracold fermionic [superscript 23]Na[superscript 40]K Feshbach molecules, and identify a two-photon pathway to the rovibrational singlet ground state via a resonantly mixed B[superscript 1]Π ~ c[superscript 3]Σ[superscript +]intermediate state. Photoass...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/100045 https://orcid.org/0000-0003-4329-5163 https://orcid.org/0000-0001-8120-8548 https://orcid.org/0000-0003-2672-5264 |
| Summary: | We report on high-resolution spectroscopy of ultracold fermionic [superscript 23]Na[superscript 40]K Feshbach molecules, and identify a two-photon pathway to the rovibrational singlet ground state via a resonantly mixed B[superscript 1]Π ~ c[superscript 3]Σ[superscript +]intermediate state. Photoassociation in a [superscript 23]Na–[superscript 40]K atomic mixture and one-photon spectroscopy on [superscript 23]Na[superscript 40]K Feshbach molecules reveal about 20 vibrational levels of the electronically excited c[superscript 3]Σ[superscript +]state. Two of these levels are found to be strongly perturbed by nearby B[superscript 1]Π levels via spin–orbit coupling, resulting in additional lines of dominant singlet character in the perturbed complex B[superscript 1}Π |v = 4〉 ~ c[superscript 3]∑[superscript +] v = 25〉, or of resonantly mixed character in B[superscript 1}Π |v = 12〉 ~ c[superscript 3]∑[superscript +] v = 35〉. The dominantly singlet level is used to locate the absolute rovibrational singlet ground state X[superscript 1]∑[superscript +] |v = 0, J = 0〉 via Autler–Townes spectroscopy. We demonstrate coherent two-photon coupling via dark state spectroscopy between the predominantly triplet Feshbach molecular state and the singlet ground state. Its binding energy is measured to be 5212.0447(1) cm[superscript −1], a thousand-fold improvement in accuracy compared to previous determinations. In their absolute singlet ground state, [superscript 23]Na[superscript 40]K molecules are chemically stable under binary collisions and possess a large electric dipole moment of 2.72 Debye. Our work thus paves the way towards the creation of strongly dipolar Fermi gases of NaK molecules. |
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