A FERMI RESONANCE STUDY IN (HCN)-C-12-N-14-(HF)-F-19 BASED ON GAS-PHASE FAR-INFRARED SPECTROSCOPY

A static gas phase far infrared spectroscopic investigation of seven h ot bands involving the intermolecular bend nu(7)(1) in the hydrogen-bo nded species HCN-HF has been performed. The information obtained from a rovibrational analysis of these hot bands is combined with previousl y available microwave and infrared spectroscopic data to reinvestigate Fermi resonance interactions 2 nu(7)(0) with nu(4) and 3 nu(7)(1) wit h nu(4)+nu(7)(1). Corresponding Fermi resonance shifts of 2.31(5) cm-( 1) and 3.04(9) cm(-1) were calculated respectively. Anharmonic constan ts chi(77) = -1.228(3) cm(-1) and g(77)-1.136(3) cm(-1) were also dete rmined and compared with values of value of chi(77) = -2.29 cm(-1) and g(77) = 1.06 cm(-1) evaluated by Amos [R.D. Amos, J.F. Gaw, N.C. Hand y, E.D. Simandiras and K. Somasundram, Theoret. Chim. Acta, 71 (15187) 41] from an ab initio calculation. (C) 1997 Elsevier Science B.V.