Multiplex integrated cavity output spectroscopy of cold PAH cations

Multiplex Integrated Cavity Output Spectroscopy (MICOS) is a new cavity-enhanced absorption method that allows the use of broadband dye nanosecond pulsed laser sources and offers a sensitivity equivalent to CRDS. MICOS has been coupled to a pulsed discharge slit nozzle to measure the spectra of the cold naphthalene (C10H8+), acenaphthene (C12H10+) and pyrene (C16H10+) cations in the gas phase. A femtosecond relaxation timescale is measured for the D5←D0 (0–0) transition of C16H10+. Spectra recorded at high plasma energies also show evidence of fragmentation. The CH radical is observed and carbon nanoparticles are generated in the plasma.