Microwave spectrum, quadrupole coupling constants, and dipole moments of 1-chloro-2-fluorobenzene

The microwave spectrum of 1-chloro-2-fluorobenzene has been reinvestigated in the frequency region 7-14 GHz by a molecular beam Fourier transform microwave spectrometer. A least-squares analysis of the observed a- and b-type transition frequencies gave rotational and quartic centrifugal distortion constants and the components of the nuclear quadrupole coupling tensor in the principal inertial axis system A = 2917.80197(42)MHz, B = 1552.12432(27)MHz, C = 1013.02869(15)MHz, D-J = 0.0366(33)kHz, D-JK = 0.3010(90)kHz, D-K = 0.263(30)kHz, d(1) = 0.0164(28)kHz, d(2) = -0.0071(17)kHz, chi(aa) = -72.9686(42)MHz, chi(bb) = 39.1771(45)MHz, Xo = 33.7915(87)MHz for 1-[Cl-35]chloro-2-fluorobenzene. The dipole moments were determined to be mu(a) = 2.28(85)D and mu(b) = 1.47(30)D. (C) 1996 Academic Press, Inc.