Jens-Kristian Krogager is an astronomer working on large spectroscopic surveys of quasars. The main scientific objective is to characterize quasar evolution and to study intervening galaxies seen as strong absorption systems. A particular focus of his research is the chemical enrichment of galaxies of cosmic time and how galaxies convert their neutral atomic gas into molecular gas. He is the PI of the 4MOST-Gaia Purely Astrometric Quasar Survey with the newly commissioned 4MOST multi-object spectrograph at the ESO/VISTA telescope and main developer of the redshift pipeline of 4MOST spectra.