Knowledge Bank

The Stark effect in sulfur dioxide and 1,2-difluoroethene has been studied using the 890,761 CHz HCN laser. Both molecules are nearly prolate, with their dipole moment along the b axis. Both molecules show similar Stark effect with low M lines crowded together at the low field region, and start to spread out as M and the field increase. The observed Stark spectrum in both molecules can be fit into a relation of the type $1/E2=A+BM2$ with B negative. Furthermore for both molecules spectra for $sigma$; and $\pi$ polarizations start at the same field. In $SO2$ the spectrum starts at 3.570 $\times 104$ v/cm with $|\Delta J|=1$ and with transition frequency below the laser. By counting the number of lines, we assign a lower limit on J as 17. In 1,2-difluoroethene, one spectrum starts at $1.293\times 104$ v/cm and another at $1.990\times 104$ v/cm, Both belong to $|\Delta J|=1$ transition with their transition frequencies below the laser. For the spectrum which starts at lower field we assign a lower limit on J as 35 and for the other lower limit on J is 32.