Fullerane

F. Cataldo and S. Iglesias-Groth (eds.), Fulleranes The Hydrogenated Fullerenes, Carbon Materials Chemistry and Physics 2, DOI 10.1007/978-l-4020-9887-l l, Springer Science+Business Media B.V. 2010... 

In this chapter, we review the possible contribution of single fullerenes, fulleranes and buckyonions to the interstellar extinction and the anomalous microwave emission. We compare their photoabsorption spectra with some of the observational properties of interstellar extinction, in particular with the characteristics of the UV bump and with the distribution of diffuse interstellar bands (DIBs) in the optical and near infrared and discuss the potential of fulleranes as carriers of anomalous microwave emission. 

A significant fraction of the fullerenes and buckyonions in the interstellar medium could be hydrogenated as discussed by Webster in 1992 (see Fig. 1.4). These molecules, named genetically as fulleranes have deserved attention as potential carriers of diffuse intestellar bands and other interstellar and circumstellar features (Webster 1991, 1992, 1993a). Both, fullerenes and fulleranes have been detected in samples of the Allende meteorite (Becker et al. 1994), see Fig. 1.3b. 

The interstellar light extiction curve at 2,175 A can be modeled using fulleranes with different degree of hydrogenation (Webster 1995 Cataldo 2003 Cataldo et al. 2009). The fraction of interstellar carbon abundance needed to produce fulleranes is high, but not prohibitively and carbon stars and planetary nebulae could provide these molecules in sufficient quantity. The experimental determination of optical and infrared spectra for laboratory-isolated fulleranes would be very valuable in assessing their role as carriers of the DIBs and of the unidentified infrared emission features. 

We will consider here the various families of fulleranes CN H that can be formed from icosahedral fullerenes with N = 60, 180, 240, 540, 960, 1,500, and 2,160 carbon atoms. Buckyonions can also be hydrogenated. We will consider here only... 

Rotation and Electric Dipole Emisivity from Fulleranes... 

Fig. 1.9 Effective rotation rates, as a function of radius for neutral fulleranes with various...

In Fig. 1.10b we plot the total flux emission curve for a mixture of fulleranes (with a number of carbon atoms N = 60-2,160) following a size distribution law n(R) aR with tn — 3.5 it 1,5 Uid compttre it with the Costnic Hcick Toiifid ItYia cv... 

In summary, it is possible to understand the Perseus molecular complex and the dark cloud LDN 1622 microwave anomalous emission in terms of electric dipole emission of fulleranes if these molecules follow a size distribution similar to that proposed in the study of the UV extinction bump. The dominant microwave emission would be associated in both cases to the smaller fulleranes. These molecules could also be responsible for the diffuse microwave dust correlated emission at high Galactic latitude detected by the COSMOSOMAS experiment and WMAP. 

Fullerenes, fulleranes and buckyonions are expected to present weaker transitions in the optical and near infrared with their number decreasing towards longer wavelengths. These transitions may be responsible for some of the known but unexplained diffuse interstellar bands. It would be very important to obtain high sensitivity, high resolution laboratory spectra of these molecules in the optical and near infrared for a more precise comparison with the very detailed observations of DIBs. 

Infrared and Ultraviolet Spectra of Fulleranes HREELS Studies and Implications for the Interstellar Medium... 

F. Cataldo and S. Iglesias-Groth (eds.), Fulleranes The Hydrogenated Fullerenes,... 

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