One-color two-photon mass-analyzed threshold ionization spectroscopy of 2-bromopropane

One-color two-photon mass-analyzed threshold ionization has been applied to 2-bromopropane (2-BP). The adiabatic ionization potential energies for the two spin states of this molecule are determined to be 81 403 ± 5 and 83 399 ± 5 cm−1, respectively. A few characteristic vibrations of the 2-BP cation are observed and assigned, which are mainly related to the C–Br stretching and CH3 motions. The C–Br bond is weakened due to the large lengthening of C–Br bond in the cationic state relative to the ground state of the neutral. These results are well supported by our theoretical calculations.