The Ground And Excited States Of Aromatic Oxide Radicals Via Anion Photoelectron Spectroscopy

Aromatic oxide free radicals play an important role in atmospheric and combustion chemistry, where they are involved in the formation of secondary organic aerosols and soot. The oxygen atom lone pairs can readily mix with the aromatic system giving rise to extensive electronic delocalization and influencing molecular reactivity. The oxygen atom also imparts a significant dipole moment to the radical system, which supports low-lying resonance and dipole bound states. We probed three cryogenically cooled aromatic oxide radicals (phenoxy, 1-naphthoxy, 2-naphthoxy) via Slow Electron Velocity Map Imaging (SEVI) to unravel their electronic and vibrational structure. We determined electron affinities and excited state energies for the three systems, and observed numerous active vibrational modes. Resonant photoexcitation to the dipole bound state was found to drastically alter the observed vibrational structure, and care was taken to avoid these resonances during direct photodetachment studies

PAHs in the Halo of NGC 5529

We present sensitive ISO $\lambda 6.7 \mu$m observations of the edge-on galaxy, NGC 5529, finding an extensive MIR halo around NGC 5529. The emission is dominated by PAHs in this band. The PAH halo has an exponential scale height of 3.7 kpc but can still be detected as far as $\approx 10$ kpc from the plane to the limits of the high dynamic range (1770/1) data. This is the most extensive PAH halo yet detected in a normal galaxy. This halo shows substructure and the PAHs likely originate from some type of disk outflow. PAHs are long-lived in a halo environment and therefore continuous replenishment from the disk is not required (unless halo PAHs are also being destroyed or removed), consistent with the current low SFR of the galaxy. The PAHs correlate spatially with halo H$\alpha$ emission, previously observed by Miller & Veilleux (2003); both components are likely excited/ionized by in-disk photons that are leaking into the halo. The presence of halo gas may be related to the environment of NGC 5529 which contains at least 17 galaxies in a small group of which NGC 5529 is the dominant member. Of these, we have identified two new companions from the SDSS.Comment: 16 pages, 5 gif figures, accepted for publication in A&A, For pdf with higher quality figures, see http://www.astro.queensu.ca/~irwi

Structure and kinematics of edge-on galaxy discs -- II. Observations of the neutral hydrogen

We present Australia Telescope Compact Array (ATCA) and Westerbork Synthesis Radio Telescope (WSRT) HI observations of 15 edge-on spiral galaxies of intermediate to late morphological type. The global properties and the distribution and kinematics of the HI gas are analysed and discussed. We determine the rotation curves using the envelope-tracing method. For 10 spiral galaxies with a stellar disc truncation we find an average ratio of the HI radius to the truncation radius of the stellar disc of 1.1 +/- 0.2 (1 sigma). This paper has been accepted by MNRAS and is available in pdf-format at the following URL: http://www.astro.rug.nl/$\sim$vdkruit/jea3/homepage/paperII.pdfComment: Accepted for oublication in MNRA