A new technique has been developed for which molecules can be selectively ionized by multi-photon excitation using laser induced excitation (e.g., two photons are sequentially absorbed to give the excited state). Experimentally it was observed that naphthalene could be selectively ionized by sequentially absorbing three photons at a wavelength of 363.24 nm. What was the experimental ionization energy for naphthalene in kJ/mole?