Carbon chemical species in size-resolved airborne particulate matters collected on January 14 and October 16–17

2010 at SINAP

a suburban spot in northwest Shanghai

and in three standard samples(oxalic acid

sucrose and graphite)

were characterized on October 19–21

2010 with the near-edge X-ray absorption fine structure(NEXAFS) spectroscopy.The C(1s) NEXAFS spectra differ distinctly among the freshly collected particulate matters of different size ranges and different collection hours

i.e.in day time or at night.The difference is mainly the asymmetrical distribution of carboxyl-COOH

carbonate and carbonyl C = O components.However

this was not observed among the C(1s) NEXAFS spectra of particulate matters collected in different hours of January 14 and kept refrigerated for 9 months

suggesting possible decay or re-equilibrium of the carbon chemical species in the sample storage.