**Abstract**

In this research we apply a sensitive laser optical technique for the measurement of main chemical elements present in the exhaust emissions generated from different in-use Diesel engine passenger vehicles. We use the laser-induced breakdown spectroscopy (LIBS) technique for diagnostics of miscellaneous Diesel particulate matter (DPM) formed from combustion Diesel engine exhaust emissions. Here we analysed particulate matter (PM) extracted from exhaust manifold part, from 67 different passenger vehicles of major brands from European car producers, that are used in daily life environment. The aim of this study is to develop LIBS technique for measurement of PM and to compare the emission matrix composition and major chemical elements within the Diesel particulate matter from exhaust manifold part. The presence of these elements in PM is linked with various processes inside the Diesel combustion engine.

**Keywords:** laser-induced breakdown spectroscopy, LIBS, particulate matter, soot, emissions, emissions standards, diesel, diesel engine, diesel vehicles

### **1. Introduction**

Problems with Diesel emissions and control failures [1–3] are well known to anyone in the world. Breathing of clean air is very important for a healthy human body—mainly for the brain and nervous system. Therefore, it should be in our first priority to find a new technique to successfully solve these issues. The current existing emission standards in Europe, like European emission standards Euro [4, 5], or in the US, like Tier [6] or LEV [7], for Diesel engine passenger vehicles are the norms for hydrocarbons, carbon monoxide, nitrogen oxides, and particulate matter (PM) from Diesel exhaust emissions. Currently, there are no specific emission standards for additional compounds or chemical elements contained in the exhaust vapour [8], particulate matter [9, 10], or soot, formed by the Diesel combustion engine [11]. But in fact, the composition of chemical elements and extra carbon corresponds to a very important fraction of the total PM or black soot emission contents from Diesel engine-driven vehicles. **Figure 1** shows the black cloud of Diesel exhaust emissions emitted from the tail pipe of on-road Diesel engine passenger vehicle.

One of the early pioneering groups in measurement of particulate trace emissions from vehicles was the group of Schauer et al. [9], where they used comprehensive

#### **Figure 1.**

*Black cloud of particulate matter and soot exhaust emissions from the tail pipe of on-road diesel engine passenger vehicle.*

dilution source sampler, organic chemical analysis, and X-ray fluorescence for fine particle mass and chemical composition measurements. Other groups [8, 10–12] used ICP-MS and XRF for characterisation of metals and other components from on-road motor vehicles. They found the following trace elements: Al, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Pt, S, Sr, Ti, V, and Zn in the particles.

In this research we apply the laser-induced breakdown spectroscopy (LIBS) technique [13–15] for diagnostics of DPM, formed from combustion Diesel engine exhaust emissions, mainly concerning the comparison of major chemical components present in various DPM matrices.

Laser-induced breakdown spectroscopy is an emerging measurement technique [16] for rapid qualitative [17] and sensitive quantitative compositional analysis [18, 19] of various forms of materials like solids [20], liquids [21], gases [22], powders [23], or nanoparticles [24].
