Laser cooling of barium monofluoride molecules using synthesized optical spectra

Abstract

We demonstrate laser cooling of barium monofluoride (^{138}BaF) molecules. We use serrodynes to synthesize time-sequenced optical spectra that can be precisely tailored to the hyperfine structure of this heaviest nonradioactive alkaline earth monofluoride. By optimizing these optical spectra, we realize strong Sisyphus cooling forces that efficiently collimate a molecular beam. Our technique is an important step toward using intense beams of barium monofluoride for precision measurement applications, and will be useful for cooling other molecular species with complex level structure.