关键词: 次氟酸, 势能函数, 振动光谱, 同位素效应

Abstract: Various isotopic species of hypofluorous acid, HOF, have been a subject of many vibrational spectroscopic studies. The object of these detailed analyses is to obtain accurate spectroscopic data of the various isotopic species of this molecule and to provide information about the structures and the potential energy surface. In this paper, some force constants of hypofluorous acid have been optimized from the comparison between the experimental and the calculated vibrational energy levels,the others have been fixed to the values of the empirical force constants given by Halenon and Ha(J. Chem. Phys. , 1988, 89: 4885).Anew potential energy function is obtained by using the transformation between the force constants and the potential energy parameters of the MORBID form suggested by Jensen(J.Mol.Spectrosc. , 1989, 133: 468. The spectra of the vibrational excited states of the molecules H¹⁶OF, H¹⁸OF, D¹⁶OF, and D¹⁸OF have been calculated by using the TRIATOM program,which uses the basis set expansion and is thus strictly variational.In molecules H¹⁸OF,D¹⁶OF, D¹⁸OF, the vibrational frequency shifts relative to HOF specie have been calculated.These calculated shifts are in agreement with the experimental values. In addition, for the vibrational excited states of the H¹⁶OF, H¹⁸OF, D¹⁸OF and D¹⁸OF, some unobserved vibrational energy levels and their isotopic effects have been predicted based on the new potential energy function of the hypofluorous acid(HOF). For molecules H¹⁸OF, D¹⁶OF, and D¹⁸OF,the vibrational frequency shifts relative to HOFspecies hold up appromately the combination rule:△v(H¹⁸OF)+△v(D¹⁶OF)≈△v(D¹⁸OF).In particular, for DOF molecule, it is shown that the stretching vibrational fundamental frequency blue shifts relative to HOFspecie is 2. 13 cm^-1, which is close to the experimental values(- 2. 10 cm^-1).For the stretching_3.vibrational excited states of the molecule DOF, the excited vibrational frequency blue shifts have been predicted, for example, the blue shift is -4.2 cm^-1,5. 6 cm^-1ands.3 cm^-1 for the vibrational states(002) , (003) and (004) of the DOF, respectively.

Key words: HOF, Potential energy function, Vibrational spectra, Isotopic effects