Fractal and spectroscopic analysis of soot from internal combustion engines M. S. Swapna, H. V. Saritha Devi, Vimal Raj and S. Sankararaman Eur. Phys. J. Plus, 133 3 (2018) 106 Published online: 14 March 2018 DOI: 10.1140/epjp/i2018-11918-y