Characterisation of the b³Σ⁺, v = 0 state and its interaction with the A¹Π state in aluminium monofluoride

Abstract

Recently, we determined the detailed energy level structure of the $X^1{\mathrm{\Sigma }}^{+}$, $A^1\mathrm{\Pi }$ and $a^3\mathrm{\Pi }$ states of AlF that are relevant to laser cooling and trapping experiments [Truppe et al., Phys. Rev. A. 100 (5), 052513 (2019)]. Here, we investigate the $b^3{\mathrm{\Sigma }}^{+},v=0$ state of the AlF molecule. A rotationally resolved (1 + 2)-REMPI spectrum of the $b^3{\mathrm{\Sigma }}^{+},v^{\prime }=0\leftarrow a^3\mathrm{\Pi },v^{″}=0$ band is presented and the lifetime of the $b^3{\mathrm{\Sigma }}^{+},v=0$ state is measured to be 190(2) ns. Hyperfine-resolved, laser-induced fluorescence spectra of the $b^3{\mathrm{\Sigma }}^{+},v^{\prime }=0\leftarrow X^1{\mathrm{\Sigma }}^{+},v^{″}=1$ and the $b^3{\mathrm{\Sigma }}^{+},v^{\prime }=0\leftarrow a^3\mathrm{\Pi },v^{″}=0$ bands are recorded to determine fine- and hyperfine structure parameters. The interaction between the $b^3{\mathrm{\Sigma }}^{+},v=0$ and the nearby $A^1\mathrm{\Pi }$ state is studied and the magnitude of the spin–orbit coupling between the two electronic states is derived using three independent methods to give a consistent value of 10(1) cm${}^{-1}$. The triplet character of the A state causes an $A\to a$ loss from the main A−X laser cooling cycle below the 10${}^{-6}$ level.

GRAPHICAL ABSTRACT

Keywords:

• Cold molecules
• laser cooling
• hyperfine-resolved spectroscopy
• spin–orbit coupling

View correction statement:

Correction

Disclosure statement

No potential conflict of interest was reported by the author(s).