Microwave Spectra of the Methylcyanopolyynes CH3(C&tbond;C)nCN, n = 2, 3, 4, 5.
The ground state rotational spectra of four methylcyanopolyynes CH3(C&tbond;C)2CN, CH3(C&tbond;C)3CN, CH3(C&tbond;C)4CN, and CH3(C&tbond;C)5CN were measured between 6 and 22 GHz by Fourier transform microwave spectroscopy. For CH3(C&tbond;C)2CN, previously observed by Alexander et al. [J. Mol. Spectrosc. 70, 84-94 (1978)] eight transitions were observed, each with sufficient resolution to determine the nitrogen quadrupole hyperfine constant for the first time: eqQ = -4.25(3) MHz. The longer three methylcyanopolyynes are new; for these, from 10 to 21 rotational transitions were detected and precise values for the rotational and the leading centrifugal distortion constants, and eqQ for CH3(C&tbond;C)3CN, were determined. Copyright 1998 Academic Press.
Chen
W
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, 02138
Grabow
J
Travers
MJ
Munrow
MR
Novick
SE
McCarthy
MC
Thaddeus
P