Abstract: Ultra-fine particulate matter (PM0.1) emission from automobile exhaust and its aging process in the atmosphere have a significant impact on human health and environmental climate. In this work, the optical absorption coefficients of PM0.1 in the exhaust of 18 automobile under no-load idle state and after 4 hours and 14 hours of light aging were researched with photoacoustic spectroscopy at 1064 nm. The results showed that the optical absorption coefficient of PM0.1 in vehicle exhaust decreases obviously after the implementation of National V standard in China, which is positively correlated with engine displacement, service life and weight and the optical absorption coefficient of PM0.1 increased first and then decreased during light aging. This work provides an experimental basis and data support for further understanding of the light absorption characteristics and environmental behavior of PM0.1 in automobile exhaust.

Key words: photoacoustic spectroscopy, automobile exhaust, ultrafine particles, optical absorption coefficient