Knowledge Bank

The optical spectra of the atomic clusters Si$3$ and S$3$ will be discussed in detail. The jet-cooled 2-colour resonant-2-photon ionisation spectrum of Si$3$ has now been detected for the first time in the 530,nm region. For Si$3$ a progression in the excited state bending and stretching modes are seen built onto the origin. Lower state frequencies derived from sequence band structure agree with those previously measured for the D low lying electronic state. For thiozone additional experiments were undertaken and progressions in the excited state bending and stretching modes are seen with frequencies of 350,cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ and 420,cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ built onto the origin band at 23053.5,cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ respectively. In this talk our results are compared to theoretical results on both the C and D forms.