ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
We apply the techniques of resonance enhanced multiphoton ionization (REMPI) and time-of-flight photoelectron spectroscopy (TOF-PES) to TiO molecules cooled in a pulsed nozzle expansion to obtain vibronic spectra of gas phase TiO+. The adiabatic first ionization energy is refined to I1(TiO)=54 999±52 cm−1=6.819±0.006 eV, which yields D0(Ti+–0) =159.9±2.2 kcal/mol. For the X 2Δ state of TiO+, we resolve spin–orbit pairs of vibrational levels for v=0–14, yielding ωe=1045±7 cm−1 and ωexe =4±1 cm−1. The spin–orbit splitting ΔEso =210±6 cm−1 permits confirmation of the state symmetry by comparison with the known spin–orbit splittings of the X 3Δ state of TiO. We also observe a new excited B 2∑+ state at T0=11 227±17 cm−1 with ωe =1020±9 cm−1 and ωexe =6±2 cm−1. This state is distinct from the A 2∑+ state (average frequency 860±60 cm−1) previously observed by Dyke and co-workers. From components of certain PESs apparently due to one or more metastable states of TiO, we infer the existence of a previously unobserved state of neutral TiO at T0=2980 cm−1, possibly the 3∑− state. Finally, we discuss the electronic structure and vibrational frequencies of TiO, TiO+, and other third row metal oxides from both molecular orbital and ligand field points of view in order to understand the ordering of electronic states and certain trends in vibrational frequencies. The molecular orbital model readily explains why nominally isoelectronic neutral and cationic metal oxides, such as TiO+ and ScO, are electronically quite dissimilar.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.456083
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