Knowledge Bank

Butenhoff and $Rohlfing1$ report that $SiC2$ has an anharmonic ground state, based on Laser-induced fluorescence studies. Presilla-Marquez and $Graham2$ report that $SiC2$ is a floppy molecule with a bending frequency of $166cm-1$. Therefore $SiC2$ and perhaps $Si2C$ may have some anharmonic behavior which can show up in Kundsen effusion mass spectrometric studies as is the case for $C3$. A thorough Knudsen-effusion mass spectrometric study of $SiC2$ and $Si2C$ was carried out: a total of 46 data sets of $SiC2$ and 52 data seta of $Si2C$ over a temperature range of 1760-2080 K were obtained. Although the main objective of this study was to measure the atomization enthalpies of small silicon-carbide clusters; we also wanted to determine the effect of any anharmonic of $SiC2$ and $Si2C$ on the experimental result, ~2000 K. Atomization enthalpies of $\Delta Ha,0=1247\pm 7$ and $\Delta Ha,0=1048\pm 10$ kJ $mol-1$ are selected for $SiC2$ and $Si2C$.