Energetics and dynamics of threshold photoion-pair formation in HF/DF

摘要

Threshold ion-pair production spectroscopy (TIPPS) has been applied to two isotopomers,HF and DF.From the high resolution (approx 0.3 cm~(-1)) TIPP spectra,the ion-pair thresholds of HF/DF have been precisely measured.Combined with the ionization energy of H(D),the electron affinity of F,and the zero point energies of HF/DF,the difference between their classical bond dissociation energies was obtained as D_e(H-F)-D_e(D-F)= 12.4+-0.5 cm~(-1).Our result provides an experimental estimate of the Born-Oppenheimer breakdown in the ground electronic state.The present work also measured the total ion-pair yield spectra of HF and DF in the threshold region,and the ion-pair formation mechanisms of these two molecules were discussed in light of the high resolution results.