Knowledge Bank

Electric dipole moments of a series of vibrational levels of the excited electronic state $A1\Sigma +(v\prime =0,1,2,3)$ of BaO are measured by two different experimental techniques Using a single mode cw dye laser, rotationally resolved excitation spectra of the bandheads of the transitions $A1\Sigma +(v\prime =0,1,2,3)-X1\Sigma +(v\prime \prime =0,1)$ are obatained. By applying electric fields (0-500 V $cm-1$) Stark-Hanle effect signals on the R(O) lines of these bands are observed. A pulsed $N2$-laser pumped dye laser is used to measure the lifetimes of the same levels by the method of delayed coincidences. With these lifetime values the dipole moments are extracted from the halfeidts of the Hanle signals. In addition to this, dipole moment values are obtained from quantum beat modulations which are superimposed on the exponential decay when an electric field is applied. The similarities and differences of the two methods are discussed. It turns out that the quantum beat technique is more reliable since saturation influences are negligible in this case. The measured dipole moments are $\mu 0=2.970,\mu 1=2.660,\mu 2=3.150\mu 3=3.180$.