ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Rotational spectra of CnO with n=2, 4, 6, and 8 have been observed by using a Fabry–Perot type Fourier-transform microwave spectrometer cooperated with a pulsed discharge nozzle. The molecules have been generated by an electric discharge of carbon suboxide diluted in Ar, and adiabatically cooled to ≈2 K in a subsequent supersonic expansion. All the observed spectra for these species are characterized as linear molecules in the 3Σ− electronic ground state. Since all the three spin sublevels have been detected even in the free-jet condition, the spin–spin coupling constants have been determined precisely as well as other spectroscopic constants. The coupling constants show rapid increase as n becomes larger, indicating smaller energy gaps between the excited 1Σ+ state and the 3Σ− ground state for the longer species. Along with the recent observation of singlet CnO (n=5, 7, and 9) [Ogata, Ohshima, and Endo, J. Am. Chem. Soc. (submitted)], the present study has established the existence of a complete set of the linear carbon-chain series CnO up to n=9 in the gas phase. The effective C=C bond lengths evaluated from the rotational constants decrease gradually to a converging value of ≈1.28 A(ring) as n becomes larger. No apparent quasilinearity has been observed in the centrifugal-distortion constants of all the members, in contrast to the relevant series of the pure carbon clusters, Cn, some of which (n=3 and 7) have shown substantial nonrigidity for the bending vibration. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.468881
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