ACCURATE DETERMINATION OF THE GROUND-STATE CONSTANTS OF H3SIF INCLUDING A(0) AND D-K(0) FROM THE NU(6),2-NU(+ -2)(6)-NU(+/-1)(6), AND 2-NU(-/+2)(6) ROVIBRATIONAL BANDS/

In order to determine ground state parameters, high-resolution FTIR sp ectra of H3SiF have been studied in the nu(3)/nu(6) (620-960 cm(-1)) a nd 2 nu(6)/nu(3) + nu(6)/2 nu(3) (1300-1800 cm(-1)) regions. The funda mentals nu(3) and nu(6), The combination band nu(3) + nu(6), and the o vertones 2 nu(6)(0), 2 nu(6)(-/+2), and 2 nu(3) have been assigned. Us ing ''ordinary'' ground state combination differences obtained from th e nu(3) and nu(6) bands, improved ground state parameters B-0, D-J(0), D-JK(0), H-JK(0), and H-KJ(0) were determined for the main isotopomer (H3SiF)-Si-28. The hot bands 2 nu(6)(+/-2) - nu(6)(+/-1), 2 nu(6)(0) - nu(6)(-/+1), and (nu(3) + nu 6+/-1) - nu(6)(+/-1) of (H3SiF)-Si-28 ha ve been assigned. The nu(6), 2 nu(6)(-/+2), and 2 nu(6)(+/-2) - nu(6)( +/-1) bands were used for the first experimental determination of the ground state constants A(0) and D-K(0), whereas (nu(3) + nu(6)(+/-1)) - nu(6)(+/-1) and 2 nu(6)(0) - nu(6)(-/+1) served for calibration purp oses, Ground state differences Delta(K, J) = E(0)(K, J) - E(0)(K - 3, J) could be calculated for K = 2 to 12. By a least-squares fit of 523 such differences, we obtained the following results (in cm(-1)): A(0) = (2.8378883 +/- 0.0000046) and D-K(0) = (1.9236 +/- 0.0020) x 10(-5). (C) 1997 Academic Press.