Microwave spectroscopy measurement of ultracold ground state molecules produced via short-range photoassociation

The high-resolution microwave (MW) spectroscopy is employed to measure the rotational structures of ultracold (RbCs)-Rb-85-Cs-133 molecules prepared in the X-1 Sigma(+) (v = 0) ground state. These ground-state molecules are created using short-range photoassociation (PA) followed by the spontaneous emission. Using a combination of continuous-wave (CW) depletion spectroscopy and photoionization (PI) technique, we obtain the MW spectroscopy by coupling the neighboring rotational levels of ground-state molecules. Based on the frequency spacing obtained from the MW spectroscopy, the rotational constant of X-1 Sigma(+) (v = 0) can be accurately determined with the rigid rotor model. The precision of the measurement by MW spectroscopy is found to be 3 orders of magnitude higher than the CW depletion spectroscopy. Our scheme provides a simple and highly accurate method for the measurement of molecular structure. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement