Abstract: Anthracene and phenanthrene have been analyzed on a self-built laser probe time-of-flight mass spectrometer. Although both compounds have the same molecular formular, their positive and negative ion mass spectra recorded on the spectrometer are very different. These differences are discussed and contributed to their different structure. The study also demonstrates the power of the instrument in structure ana lysis and laser plasma studies.

Key words: Laser plasma, Time-of-flight mass spectra, Anthracene, Phenanthrene