Rovibrational optical cooling of Rb₂ in a supersonic beam

In this work, we propose to optically cool the rotation and the vibration of Rb₂ molecules in a supersonic beam by applying a spectrally shaped broadband light source, which consists of several multimode diodes, in the range of 680 - 730 nm. Optical transitions from X¹Σ_g⁺ ground state to the B¹Π_u excited potential can be driven by such source. The shaped spectrum is such that the X¹Σ_g⁺(v_x = 0, J_x = 0) and X¹Σ_g⁺(v_x = 0, J_x = 1) ground states will be a dark states. The molecules will be observed by photoionization technique, through transitions from the X¹Σ_g⁺(v_x, J_x)  to B¹Π_u(v_B, J_B) potential using a CW diode laser, and then photoionized by a 532 nm pulsed laser. Such technique will allow us to resolve the rotational distribution of the X¹Σ_g⁺(v_x = 0). Theoretical simulations indicate that we should be able to perform the rovibrational cooling with this arrangement of lasers.