High-resolution infrared and millimeter-wave study of the Fermi-coupled v(2)=1 and v(3)=2 states of DSiF3

The v(2) (v(eff) 854.841 cm(-1)) and 2v(3) infrared bands (v(eff) 840.083 c m(-1)) of DSiF3 have been studied with a resolution of 2.5 x 10(-3) cm(-1). Moreover. millimeter-wave transitions in the v(2) = 1 and v(3) = 2 states up to J" = 33 have been measured. The assignments and fit of the poorly res olved, compressed cluster-type 2v(3) IR transitions have been confirmed by a simultaneous study of the 2v(3)-v(3) band. The constant W = 5.116 cm(-1) of the Fermi interaction between the v(2) = 1 and v(3) = 2 levels has been determined from frequency effects which are in agreement with relative inte nsities of the v(2) and 2v(3) bands. The deperturbed (B-0-B-v) and (C-0-C-v ) values of the states involved agree with their ob initio predictions with in 7% in the worst case. (C) 2001 Academic Press.