Raman characteristics of PM emitted by a diesel engine equipped with a NTP reactor

Physicochemical property changes during oxidation process for diesel PM sampled at different tailpipe positions

“…The nanostructures observed by high resolution transmission electron microscopy (HRTEM) figures are mutually complementary with Raman spectra. Crystallite size calculated using Raman parameters shows consistency with HRTEM results [8]. Raman spectra present information about vibration and rotation of molecules crystal lattice, which is reflected by amorphous carbon and graphitized carbon [17][18][19] that are closely related to PM oxidation activity, however, the relations of Raman spectra and PM oxidation activity are still in debated [7,8,20,21].…”

“…Raman spectra indicated crystallite defects and carbon graphitization that was around 1350 cm -1 and 1580cm -1 respectively. Raman spectra presented closely related to PM oxidation activity, while it was still in debate [7,8,39]. Fig.…”

“…Diesel PM captured on DPF should be oxidized periodically to keep excellent performance. The oxidation behaviors of diesel PM are closely related to engine operation conditions, fuel properties, cylinder combustion and sampling conditions [4][5][6][7][8][9]. The factors mentioned above lead to the differences of diesel PM physicochemical properties that are considered to be fundamental factors causing the distinctions of oxidation activity.…”

Oxidation Activity Restoration of Diesel Particulate Matter by Aging in Air

“…The crystallite size obtained using HRTEM images is similar to the results calculated using Raman spectra and XRD parameters, and they are mutual complementation 17,[24][25][26] . The Raman spectra present the degree of lattice defects and carbon graphitization that show closely relations with PM oxidation activity 4,17,27 . However, the relations of Raman spectra parameters and oxidation activity are still in debate 17,28,29 .…”

“…However, particulate matter (PM) emitted by diesel engines has brought about negative effects on human health and environment 2,3 . Legislations limit diesel PM emissions both in mass and number that many measurements have been done to meet the legislations [4][5][6][7][8] .…”