Effect of isotopic substitution in the electronic absorption spectrum of acetone: VUV photoabsorption studies of acetone-d6

The VUV photoabsorption spectrum of acetone-d6 is recorded in the energy region 6-10 eV using synchrotron radiation at a resolving power of∼1000. Extensive Rydberg series are observed converging to its first ionization limit (9.708 eV). Quantum defect analysis and vibronic analysis of higher Rydberg series members have been reported for the first time. A comparative study of the Rydberg series and accompanying vibronic structure observed in acetone-h6 and acetone-d6 has clarified and consolidated many of the vibronic assignments. The frequency of the ν19′ mode (CO in-plane bend) of the 3py state is obtained as 340±5 cm−1 on the basis of observation of an extensive progression of this mode.

► VUV photoabsorption studies of acetone-d6 up to its first ionization limit. ► Quantum defect analysis of higher Rydberg series for the first time. ► Vibronic analysis of higher Rydberg series for the first time. ► Vibronic assignments confirmed and consolidated using isotopic substitution. ► The frequency of the ν19′ mode in the 3py state is proposed to be 340±5 cm−1.