Photoionization of tris(2-phenylpyridine)iridium

The photoionization of gas-phase tris(2-phenylpyridine)iridium (Ir(ppy)3) has been examined. One- and two-photon studies yield a conservative estimate for the upper bound to the ionization energy of 6.4 eV. The one-photon experiment used 193 nm radiation. The latter experiments used tunable UV radiation to excite the ligand-centered 1LC state, which is followed by radiationless decay and photoionization. An accompanying paper presents a theoretical study of excited singlets and triplets and low-energy states of . The calculated ionization energy is ∼5.9 eV. The experimental and calculated results together indicate an ionization energy of ∼6 eV. An undulation in the ion yield spectrum (∼270 cm−1 spacing) was observed. It is due to structure in the transition that originates from T1, which is populated through radiationless decay of 1LC. At low fluence, is produced without fragmentation, despite the fact that a large amount of vibrational energy is present in T1. Specifically, this vibrational energy is the...