摘要:

The number and mass size distributions of refractory black carbon (rBC) cores in particles emitted from a diesel vehicle were investigated as a function of particle mobility diameter (d(mob)) using a single particle soot photometer (SP2) and a differential mobility analyzer (DMA). The thickness and mass of coatings on the rBC cores were characterized. On the basis of the SP2 and DMA results, the physical properties of particles containing rBC, including effective density (rho(eff)), mass-mobility scaling exponent (D-m), dynamic shape factor (chi), and mass absorption cross section (MAC), were derived as a function of d(mob). At each d(mob), the count median diameter (CMD) of the rBC cores was essentially the same as their mass median diameter (MMD), which increased linearly with d(mob). The mass of the rBC cores was proportional to the cubic of their d(mob). However, coating thickness on rBC cores remained unchanged with d(mob), with an average thickness of 28.72 +/- 4.81 nm. For particles containing rBC, rho(eff) decreased and chi increased with d(mob). The D-m of particles containing rBC was calculated to be 2.09. At 355 and 532 nm wavelengths, the MAC of the diesel particles containing rBC was inversely dependent on d(mob).