One-color two-photon ionization of 1-bromopropane, resulting in the 1-C3H7Br+ ions in the (X) over tilde E-2(1)1/2 and (X) over tilde E-2(2)1/2 electronic states, is investigated using mass-analyzed threshold ionization (MATI) spectroscopy. The adiabatic ionization energies of two spin states are found to be 82257 +/- 5 and 84823 +/- 5 cm(-1), respectively. The two-photon MATI spectrum exhibits an extensive vibrational structure. The active modes, including the C-Br stretching, the CH2-Br wagging, the CH, and the CH3 rocking modes, are observed and reliable values for these vibrational frequencies are obtained. We have also performed ab initio and density functional calculations, which provide interpretation for our experimental finding. (c) 2005 Elsevier B.V. All rights reserved.