Fourier-transform spectroscopy of NaRb

The heteronuclear alkali dimers attract interest of both experimental and theoretical researchers involved in collision dynamics, photoassociative spectroscopy, laser cooling and trapping of alkali atoms. A special interest is put on the study of the ground states and especially near the asymptotic region, since the precise knowledge of the long-range interactions between two different types of alkali atoms is necessary for understanding and realization of such cold collision processes as sympathetic cooling, formation of two species BEC and ultracold heteronuclear molecules. Experimental information on the ground singlet and triplet states of the NaRb molecule is still limited [1-3]. Therefore the goal of the present investigation was to study the ground X1Σ+ and a3Σ+electronic states of the NaRb molecule with the help of the Fourier-transform spectroscopy. In the present experiment high-resolution Fourier-transform spectra of the NaRb molecule from laser induced fluorescence (LIF) were obtained. NaRb molecules were formed in a heat pipe oven. LIF was excited by an Ar+ laser, dye laser (R6G) and a single-mode frequency doubled cw Nd:YAG laser. This allowed us observing the B1Π → X1Σ+, D1Π → X1Σ+ and C1Σ+ → X1Σ+ band systems. Also transitions to the triplet a3Σ+ state were observed with partially resolved hyperfine structure by exciting the strongly mixed B1Π − c3Σ+ − b3Π complex