Knowledge Bank

A variation on the technique of velocity-aligned Doppler spectroscopy has been used to measure the relative populations in the F=0 and F=1 nuclear hyperfine levels in the ground electronic state of atomic hydrogen produced in the 193 nm photolysis of HBr. This technique provides an unambiguous correlation between the H atom state distributions and the spin-orbit states of the counter fragment, i.e. Br($\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}P3/2$) and Br($\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}P1/2$). H atom state distributions are monitored by observing the (1+1) two-color multiphoton ionization spectrum exciting through the Lyman-$\alpha$ transition. Effects of small Stark fields on the observed spectra will be discussed.