Knowledge Bank

A new Stark cell capable of producing higher electric field intensities than had been before achieved was built and used to examine the pure rotation infrared spectrum of the hydrogen molecule. The higher field intensities were achieved by the elimination of plastic spacers traditionally used in previous Stark cells between the parallell plate electrodes. Operating field intensities of 200,000 volts/cm are easily obtained in compressed hydrogen at a pressure of 400 p.s.i., compared to a previous maximum of 135,000 volts/cm at 550 p.s.i. in a similar cell. Peak field intensity in the new cell just before breakdown is 240,000 volts/cm in hydrogen at 400 p.s.i. The fundamental vibration-rotation spectrum and the pure rotation spectrum of hydrogen were observed using the new cell. The pure rotation spectrum was measured since it has not been observed before using the electric field induced method. The wave numbers of the $S0(1),S0(2)$ and $S0(3)$ transitions were measured to be $587.079cm-1,814.523cm-1,1034.765cm-1$ respectively. These values were used to calculate the molecular constants of hydrogen. The calculated value for $Bo$ was 59.332, for $Do:0.0450$ and for $Ho:3.1\times 10-5$, in cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$.