The Discovery of the Long Carbon Chain Polyynes in Space
Vega Lecture series Eight Lectures on Molecules in Space presented at FSU 2004 http://vega.org.uk/video/subseries/16
The Algonquin Park Telescope with which we discovered the long carbon chain polyynes
This reviews the laboratory microwave and astrophysical radio studies of the polyynes which uncovered the existance of the long carbon chains in the interstellar medium. It was this series of studies which ultimately led to the discovery of the fullerenes in 1985 and later fullerenes in space.
- HC5N http://adsabs.harvard.edu/full/1976ApJ…205L.173A
- HC7N http://adsabs.harvard.edu/full/1978ApJ…219L.133K
- HC9N http://fermi.uchicago.edu/publications/PDF/oka081.pdf
David Walton who developed the methods to synthesise long carbon chain molecules which we studied spectroscopically and with hindsight can be seen to be the seed which ultimately led to the discovery of C60
- Reviews http://www.tandfonline.com/doi/abs/10.1080/01442358109353324?journalCode=trpc20
This review considers the spectroscopic observations which have led to the identification of more than 50 molecules in the interstellar medium. Although it concentrates on the results of radio studies, mainly because these have up to now been the most revealing, optical and infrared discoveries are also reviewed and placed in perspective. The radio data yield information about the very cold regions whereas the infrared data yield information about the warmer regions where stars are forming. Optical emission studies can give information about extremely hot regions near stars and absorption studies give information about the cold regions.
The review begins with a historical introduction to the field followed by a brief overview of the interstellar medium and its relationship with other objects in the Universe in the second section. The third section is devoted to an understanding of the relevant types of spectra, mainly rotational, and salient astronomical details which pertain mainly to radio observations. In the fourth section the optical, radio and infrared spectra of various molecules are individually discussed and some of the most important regions where molecules are found are described. The various interstellar chemical pathways currently being actively studied are discussed in the fifth section. In the final section some of the more important outstanding problems and possible future research avenues are highlighted.
The overall perspective is a spectroscopic one in which the value to chemistry of these studies is deemed as interesting and significant as the value to astronomy.
This reply to my letter asking if he was interested in searching for HC5N, from Takeshi started our radioastronomy collaboration (with Lorne Avery, Norm Broten and John McLeod at NRC) which discovered the unexpected abundance of the long chain polyynes in the ISM and can in retrospect can be seen as the seed which led to the discovery of C60. Note that there are as many verys s there are carbon atoms!
Images of the radio lines detected for HC5N, HC7N and HC9N
This is a Polaroid image taken at the moment that we first saw the integrated data when we detected the line of HC7N in the Taurus molecular cloud TMC1
Other related papers http://adsabs.harvard.edu/full/1987ApJ…314..352K