Detection of Polycyclic Aromatic Hydrocarbons on individual particles

In order to extend the chemical classification of the ATOF-MS (see tab above) to several classes of (health-relevant) molecules our group investigates complex laser desorption and ionization schemes. In a recent experiment (Passig et al., 2017) we hit single particles with a sequence of three consecutive laser pulses of different wavelength to desorb and selectively ionize the health-relevant polycyclic aromatic hydrocarbons (PAHs) while the refractive elements from the particle core are exclusively ionized by the last, intense UV pulse (Fig. 1b-e). In order to assign the resulting ions to the respective ionization process, the extraction electrodes polarity is reversed within a few hundred nanoseconds between the laser pulses leading to an opposite acceleration of the ions into one of the respective ion flight tubes of the mass spectrometer. Our approach provides both a fully-fledged mass spectrum of (carcinogenic) PAHs in a single particle (Fig. 2, red) and the elemental composition of its core (blue). Consequently, the individual PAH-distribution of single-particles in aerosols and its assignment to specific pollution sources become accessible for the first time.