The dissociation of the hydrogen metastable ions was studied using a pulsed ion source mass spectrometer. The pressure dependence of the hydrogen metastable ions from H2, HD and D2 indicates that they are all produced by the collision process in the ion source between the respective parent ion and neutral species. The appearance potential of each hydrogen metastable ion has an intermediate value between the ionization potential of the parent molecule and the appearance potential of the fragment ion, and this hydrogen metastable ion may be in a vibronic excited electronic ground state of the parent ion. The kinetic energy(K. E.)released during dissociation from each hydrogen metastable ion has an approximate relation, K. E. ≈ A. P.(m*)-I. P.(m0)+E0, where A. P.(m*)is the appearance potential of the hydrogen metastable ion, I. P.(m 0)is the ionization potential of the hydrogen molecule and E0 is the zero-point energy of the respective parent ion of the electronic ground state. The observed dissociation rate constants of the hydrogen metastable ions well agree with those of the approximate theoretical calculation provided that the dissociation is caused by the quantum mechanical tunnel effect.
抄録全体を表示