Isotopic effects in the ground state of the non-symmetrical isotopomers of CuCl2 Original Research Article

The rovibrational structure of the ground state of the non-symmetrical isotopomers of CuCl2(35Cl63Cu37Cl and 35Cl65Cu37Cl) has been investigated. Laser induced fluorescence spectra were recorded on a BOMEM DA03 Fourier transform spectrometer in the range 10000–16500 cm−1 for ν″1 = 0–12 and ν″3 = 0–8. A non-linear least-squares minimization allows to obtain both rovibrational constants and isotopic factors by fitting data of one symmetrical isotopomer of CuCl2 with the corresponding non-symmetrical isotopomer having the same copper isotope. The RMS deviation is better than 0.029 cm−1 for each case. We discuss the isotopic effects and show that breakdown of the Born-Oppenheimer approximation has to be considered.