Abstract

In an earlier experiment, Quesada et al.¹ have observed the Autler-Townes splitting (also known as ac, optical, or dynamic Stark splitting) in the two-color four-photon ionization of H₂ via the double resonant levels $E,F^1{\Sigma }_g^{+}(v=6,J=1)$ and D¹Π_u (ν′ =2, J′ = 2). By fitting the calculated spectra with the observed spectra, they deduced the vibronic transition moment between these two states. We present the theory for determining a number of the vibronic transition moments between the same two electronic states and thereby deducing the electronic transition moment by an inversion scheme. We calculate the Autler-Townes spectra for some representative bands of ${\text{H}}_2\left(D^1{\Pi }_u-E,F^1{\Sigma }_g^{+}\right)$ and examine their dependences on laser detuning, intensity, bandwidth, and the Doppler effect. As input to our calculation, the D – E,F(v′ = 0—14, ν =1, 4, and 6) vibronic transition moments have been computed. Our investigation shows that the Autler-Townes splitting of a sufficient number of D—E,F vibronic transitions in H₂ should be observable so that its electronic transition moment can be deduced.

© 1988 Optical Society of America