The C7 cluster: structure and infrared frequencies

Science  24 Aug 1990:
Vol. 249, Issue 4971, pp. 895-897
DOI: 10.1126/science.11538081


Observation and characterization of the C7 cluster are reported. Carbon clusters are produced by laser vaporization of a graphite target followed by supersonic expansion of the vaporized material within a gas dynamically focused argon jet. Thirty-six sequential rovibrational lines of the nu 4 antisymmetric stretch fundamental of C7 are probed by gated detection of diode laser absorption. The observed spectrum is characteristic of a symmetrical linear molecule. Analysis of the spectrum indicates an effective average bond length of 1.2736(4) angstroms and a vibrational frequency of 2138.1951(10) reciprocal centimeters, in excellent agreement with ab initio calculations. This work will facilitate the astrophysical detection of this cluster.