Molecules consisting of an alkali-metal atom and an alkaline-earth-metal atom have both electric and magnetic dipole moments which make them appealing candidates for experimental research of molecular quantum gases. To create such molecules, accurate descriptions of their quantum states are necessary. We derive it by spectroscopic analysis of molecules of this class in the gas phase. We record the thermal emission spectrum in the near infrared region and obtain detailed data for the proper assignment of the rovibrational quantum states via spectroscopy of laser-induced fluorescences. We apply theoretical models for analysing such spectra originating from coupled molecular states and include information of cold collisions as much as it is available from our own or other research groups. Presently, this part concentrates on group Ia diatomics and will be extended to molecules from group IA and IIA elements when sufficient data become available.