Knowledge Bank

Pseudo-gas phase photoluminescence spectra of TiO isolated In Ne matrices at $4\circ K$ have been observed. Photoluminescence was induced by laser excitation from the $X3\Delta$ ground state to $B3\Pi$ and $C3\Delta$ vibronic levels using a cw Tunable dye laser and a cu argon ion laser, respectively. Red emission from $B3\Pi$ vibronic levels terminating in ground state levels was observed. In addition, the $B3\Pi$ ($v=0$) and $B3\Pi$($v=1$) levels have been found to undergo matrix-induced Intersystem relaxation into the $b1\Pi$ state. Near-infrared emission between excited states in the singlet manifold of TiO has been observed and identified as belonging to $\delta (b1\Pi a1\Delta$) and $\varphi (b1\Pi -d1\Delta +$) band systems. Observed $\delta$ and $\varphi$ emission bands are uniformly shifted by $-93cm-1$ and $+73cm-1$, respectively, from observed or predicted gas phase band heads. The line shape of the $\delta$ and $\varphi$ vibronic emission in the solid is that of a sharp zero-phonon line accompanied by a broad multiphonon sideband. An additional sharp zero-phonon emission system, here labeled the $\xi$ system,was found to overlap severlap several broad multiphonon bands of the red $\gamma \prime (B3\Pi \to X3\Delta$) emission. Evidence obtained indicates that the $\xi$ system is due to intercombination $B1\Pi \to X3\Delta$ emission. From the assigned intercombination transition the energy of the low-lying a $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta$ a state is determined to e $3500cm-1$ above the $X3\Delta$ ground state. The $3500cm-1$ value for the relative energy between the isoconfigurational $a3\Delta$ and $X3\Delta$ states is in qualitative agreement with theoretical expectations based on consideration of the bonding in the TiO molecule.