@Article{A800286J,
author ="Thaddeus, P. and C. McCarthy, M. and J. Travers, M. and A. Gottlieb, C. and Chen, W.",
title  ="New carbon chains in the laboratory and in interstellar space",
journal  ="Faraday Discuss.",
year  ="1998",
volume  ="109",
issue  ="0",
pages  ="121-135",
publisher  ="The Royal Society of Chemistry",
doi  ="10.1039/A800286J",
url  ="http://dx.doi.org/10.1039/A800286J",
abstract  ="Twenty seven new carbon-chain molecules have been detected over the past two years with a Fourier-transform microwave (FTM) spectrometer{,} 13 of which are reported here for the first time. Of the 27{,} 11 are closed shell polyynes{,} 9 are free radicals{,} 2 are cumulene carbenes{,} and 5 are carbenes formed by substituting carbon chains for one of the hydrogen atoms of the three member carbene ring CH. All the astronomically interesting rotational transitions [including hyperfine structure (hfs) for the radicals] of the entire set have either been measured to high precision{,} or are readily calculated to comparable accuracy from the spectroscopic constants derived from the laboratory data. On the basis of this data{,} 4 of the chains (CH{,} CH{,} HC{,} and HCN) have already been detected in astronomical sources and{,} with large radio telescopes under construction or the discovery of better astronomical sources{,} it is possible that nearly all can be found. Astronomical detection is aided by the apparent high polarity of all unsymmetrical chains. The sensitivity of the present liquid-nitrogen-cooled spectrometer is far from fundamental limits; an increase by one to two orders or magnitude is possible with liquid helium cooling and other refinements{,} and better precursor gases may be found. Many of the chains here probably have low-lying isomers{,} and ionized and radical variations{,} which may be detected by the present techniques. Carbon chains are hard to stretch but easy to bend: centrifugal distortion is well described by a classical model according to which all chains distort under rotation like classical thin rods with the same Young{'}s modulus: =1.7[times]10 dyn cm{,} larger than that of diamond; the longest two chains we have detected{,} HCN and HCN{,} have low frequency bending vibrations which lie within the range of existing high altitude radio telescopes. Finally{,} it is pointed out that the density of the chains at the limit of detection in our spectrometer{,} . 10 cm{,} is high by the standards of modern laser spectroscopy{,} so that optical detection of many should be possible."}