title: The C7 cluster:  structure and infrared frequencies.
abstract: 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.
authors.affiliation: Department of Chemistry, University of California, Berkeley 94720, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Heath
authors.forename: R A
authors.initials: RA
authors.lastname: Sheeks
authors.forename: A L
authors.initials: AL
authors.lastname: Cooksy
authors.forename: R J
authors.initials: RJ
authors.lastname: Saykally
mesh_terms: D001128:Argon; D001256:Astronomy / Q000295:instrumentation / Q000379:methods*; D002244:Carbon / Q000032:analysis* / Q000737:chemistry*; D007834:Lasers; D016082:Solar System; D013055:Spectrophotometry, Infrared; D013057:Spectrum Analysis
chemical_list: D001128:Argon; D002244:Carbon