Molecular absorption and evolution mechanisms of PM2.5 brown carbon revealed by electrospray ionization -Fourier-transform ion cyclotron resonance mass spectrometry during a severe winter pollution episode in Xi'an, China

42  PM2.5 samples were collected during a severe pollution episode in January 2017 over Xi’an, China for a comprehensive non-target and full scanning of Brown carbon molecules and their absorption properties using electrospray ionization–Fourier-transform ion cyclotron resonance mass spectrometry(FTICRMS). Here are the data sets of FTICRMS intensity, formula, organic carbon (OC) and absorption at 365nm of the 42 samples.