Stark Effect of Metastable Hydrogen Molecules

The molecular-beam magnetic-resonance method has been used to measure the Stark effect of the metastable $c{}_{}{}^3{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ electronic state of ${\mathrm{H}}_2$. The magnitude of the effect is found to be about ${10}^4$ times greater than for the ground electronic state and to depend sensitively upon vibrational quantum number. A theoretical treatment of the effect has allowed us to identify at least three vibrational states of ${\mathrm{H}}_2$ which are metastable, including $v=0\mathrm{} \mathrm{and} 1$.