Knowledge Bank

Collision diameters for some select transitions in the rotational spectrum of $H2CO$ have been determined using pressure broadening of the spectral lines. Transitions of the type $\Delta J=0$ and $\Delta \tau =1$ with $1\le J\le 6$ were investigated for both self-broadening and foreign gas brodening (He and $H2$) of the spectral lines. Pressure ranges from 0.001 Torr to 0.1 Torr were explored in obtaining the line width parameters $\Delta \nu 0$ for each transition. Collision diameters were found to range over 12 {\AA} to 35 {\AA} for $H2CO-H2CO$ interaction, 5 {\AA} to 8 {\AA} for $H2CO-H2$ interaction and 4 {\AA} to 9 {\AA} for $H_{2}CO - $He interaction.