Laser‐induced molecular ion formation and gas‐phase ion formation from polycyclic aromatic hydrocarbons, coals and coal products detected by Fourier transform mass spectrometry

Abstract

AbstractThe results from the laser‐ablation Fourier transform mass spectrometric examination of a variety of polyaromatic hydrocarbons (PAHs), coals and other geochemically related materials are presented. Both molecular and quasi‐molecular ions have been detected from different ring‐sized PAHs. A relationship between the ease of sodium‐adduct ion formation and the size of the aromatic array is observed. Nevertheless, suppression of [M + Na]+ ion formation in PAHs can be achieved by the addition of coal. In addition, distributions of low‐mass positive‐ and negative‐ion carbon clusters (Cn +, 14 ⩽ n ⩽ 27 and Cn, −, 4 ⩽ n ⩽ 30), high‐mass positive‐ion carbon clusters (Cn+, 60 ⩽ n ⩽ 260) and low relative molecular mass organic compounds (< 600 daltons) have been observed from the coals. It appears that the ease of C formation may be used as an indicator of coal rank. Irradiance conditions also influence the observed distribution of high‐mass positive‐ion carbon clusters. Furthermore, distributions of the high‐mass positive‐ion carbon clusters at different irradiances supports an earlier proposal that their formation is kinetically controlled.