Infrared spectroscopy of ruthenium tetroxide and high-resolution analysis of the ν3 band

Abstract RuO 4 is a heavy tetrahedral molecule which has practical uses for several industrial fields. Due to its chemical toxicity and the radiological impact of its 103 and 106 isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. New, higher resolution FTIR spectra have been recorded at room temperature, using an isotopic pure sample of 102 RuO 4 and a sample with all stable isotopes present in natural abundance. We reinvestigate here the strong ν 3 stretching fundamental region and perform new assignments and effective Hamiltonian parameter fits for the five main isotopologues ( 99 RuO 4 , 100 RuO 4 , 101 RuO 4 , 102 RuO 4 and 104 RuO 4 ), by considering the ν 3 stretching mode as an isolated band. We provide precise effective Hamiltonian parameters, including band centers and Coriolis interaction parameters. We discuss isotopic shifts and estimate the band centers for the two minor isotopologues ( 97 RuO 4 and 98 RuO 4 ) and the two radioactive isotopologues ( 103 RuO 4 and 106 RuO 4 ). Experimental band strengths for the two IR active fundamentals are also reported for the first time.