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This work reports on a first successful spectroscopic investigation of the van der Waals molecule NaXe. The molecules were produced by supersonic expansion of a mixture of sodium vapor and xenon gas through a nozzle into a vacuum. The absorption spectrum due to the transition $A\Pi \leftarrow x\Sigma$ of NaXe has been recorded with high resolution for wavenumbers between 16800 and $16900cm-1$ using a tunable single-mode dye laser. In addition, a low resolution scan has been performed between 16470 and $16950cm-1$. Due to the presence of 5 stable Xe isotopes with relative abundance of more than 5% in natural mixture of isotopes the observed absorption spectrum of NaXe is highly congested. An assignment of rotational quantum numbers was only possible by extensive application of the method of optical-optical double resonance which produces isotope-selective signals. Up to now, four vibrational transitions from the $x\Sigma v\prime \prime =0$ level to the $A\Pi 3/2v\prime$ and $v\prime +2$ level and to the $A\Pi 1/2(v\prime +1)$ and $v\prime +2$ level have been analysed for the 3 Xe isotopes 129, 131 and 132 with relative abundance of 26.4, 21.2 and 26.9% resp. From about 70 rotational lines per isotope and per vibrational transition we have determined preliminary values for the parameters of molecular rotation. As an example the rotational constants of $NaXe132$ turn out to be $B(v\prime \prime =0)=1.038(1)GHz$ and $B(v\prime )=1.614(1)GHz$. A vibrational assignment has not been possible up to now. However, from the results of previous model potential calculations we expect $v\prime$ to be around 13. As a result of our low-resolution scan we could estimate the fine structure splitting between the $A\Pi 1/2v\prime$ and the $A\Pi 3/2v\prime$ state of NaXe to be about 480 GHz.