High-resolution optical spectroscopy of buffer-gas-cooled silicon monofluoride (²⁸Si¹⁹F)

Precise measurement of high-resolution molecular spectroscopy plays an important role in elucidating the quantum nature governing the molecular properties and in exploring fundamental physics and chemistry. Here, we report the high-resolution optical spectroscopy of buffergas-cooled silicon monofluoride (²⁸Si¹⁹F, hereafter SiF) molecules in the A ²Σ⁺ (υ′ = 0) ← X ²Π_1/2 (υ = 0) transition. We measured a total of 94 hyperfine-resolved transitions with an uncertainty of 13.8 MHz via the laser-induced fluorescence technique, enabling the first determination of the hyperfine constant b and dipole–dipole interaction constant c of the A ²Σ⁺ state arising from the ¹⁹F. By employing an effective Hamiltonian analysis, we reconstructed the hyperfine energy level structures for both ground and excited states, providing a comprehensive spectroscopic framework for SiF. These results establish SiF as a promising candidate for laser cooling, though the measured hyperfine splitting suggests that multiple frequency components will be required to achieve efficient optical cycling. Our findings enrich the spectroscopic database for cold SiF molecules, advancing their potential applications in quantum control, precision measurement, astrophysics, and plasma physics.