Knowledge Bank

Tantalum methylidyne, TaCH, has been produced in a supersonic free jet expansion in helium by the reaction between laser ablated tantalum and methan e. TaCD has been made similarly using $CD4$. Pulsed dye laser excitation spectra from the $\Omega =0(X~\Sigma +$) state of TaCH have been assigned to two electronic transitions whose upper states have $\Omega =0+$ which proably is $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Pi$, and $\Omega =1$. The (0,0) bands of these states lie at 15638.6 cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ and 16398.3 cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$, respectively. Wavelength resolved fluorescence emission from the $\Omega =O+$ excited state has revealed a low lying $\Omega =1$ electronic state $3620cm-1$ above the ground state; this appears to be a $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Delta$ state. Two of the $X~$ state vibrational fundamentals have been determined for TaCH(TaCD): $\nu 2=641(492)$ cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ and $\nu 3=955(910)$ cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$. The values determined for the $a3\Delta t$ state were $\nu 2=606(449)$ cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ and $\nu 3=925(864)$ cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$. High resolution spectra are being recorded for selected bands; these will allow the molecular structure and the spectroscopic parameters to be detedmined accurately. The magnetic and quadrupolar hyperfine structure of $\mathrm{<mrow\; data-mjx-texclass="ORD">181</mrow>}$Ta is fully resolved in the high resolution study.