Radiative lifetime of the A 2{\Pi}1/2 state in RaF with relevance to laser cooling

• Published in: arXiv.org 2024-03
• Main Authors: Athanasakis-Kaklamanakis, M, Wilkins, S G, Lassègues, P, Lalanne, L, Reilly, J R, Ahmad, O, M Au, Bai, S W, Berbalk, J, Bernerd, C, Borschevsky, A, Breier, A A, Chrysalidis, K, Cocolios, T E, de Groote, R P, Fajardo-Zambrano, C M, Flanagan, K T, Franchoo, S, Garcia Ruiz, R F, Hanstorp, D, Heinke, R, Imgram, P, Koszorús, A, Kyuberis, A A, Lim, J, Liu, Y C, Lynch, K M, McGlone, A, Mei, W C, Neyens, G, Nies, L, Oleynichenko, A V, Raggio, A, Rothe, S, Skripnikov, L V, Smets, E, van den Borne, B, Warbinek, J, Wessolek, J, Yang, X F, the ISOLDE Collaboration
• Format: Article
• Language: English
• Subjects: Cooling; Decay rate; Laser cooling; Lasers; Photon scatter; Photons; Radiative lifetime; Radium
• ISSN: 2331-8422

The radiative lifetime of the \(A\) \(^2 \Pi_{1/2}\) (v=0) state in radium monofluoride (RaF) is measured to be 35(1) ns. The lifetime of this state is of relevance to the laser cooling of RaF via the optically closed \(A\) \(^2 \Pi_{1/2} \leftarrow X\) \(^2\Sigma_{1/2}\) transition, which is an advantageous aspect of the molecule for its promise as a probe for new physics. The radiative decay rate \(\Gamma = 2.9(2)\times 10^7\) s\(^{-1}\) is extracted using the lifetime, which determines the natural linewidth of 4.6(3) MHz and the maximum photon scattering rate of \(4.1(3)\times 10^6\) s\(^{-1}\) of the laser-cooling transition. RaF is thus found to have a comparable photon-scattering rate with other laser-cooled molecules, while thanks to its highly diagonal Franck-Condon matrix it is expected to scatter an order of magnitude more photons when using 3 cooling lasers before it decays to a dark state. The lifetime measurement in RaF is benchmarked by measuring the lifetime of the \(8P_{3/2}\) state in Fr to be 83(3) ns, in agreement with literature.