ATLASGAL dense clumps Molecular parameters

The sample is selected from the 10000 clumps identified by the ATLASGAL (APEX Telescope Large Area Survey of the Galaxy) survey and includes all of the most important embedded evolutionary stages associated with massive star formation, classified into five distinct categories (quiescent, protostellar, young stellar objects, HII regions, and photon-dominated regions).

The observations were performed in broad-band mode with frequency coverage of 85.2-93.4GHz and a velocity resolution of ~0.9km/s, detecting emission from 26 different transitions. We find significant evolutionary trends in the detection rates, integrated line intensities, and abundances of many of the transitions and also identify a couple of molecules that appear to be invariant to changes in the dust temperature and evolutionary stage [N_2_H^+^ (1-0) and HN^13^C (1-0)].