We have demonstrated quantum control of the spin-orbit interaction based on the Autler-Townes (ac-Stark) effect in a molecular system using a cw optical field. We show that the enhancement of the spin-orbit interaction between a pair of weakly interacting singlet-triplet rovibrational levels, G (1)Π(g)(v=12,J=21,f)-1 (3)Σ(g)(-)(v=1,N=21,f), separated by 750 MHz in the lithium dimer, depends on the Rabi frequency (laser power) of the control laser. The increase in the spin-orbit interaction due to the control field is observed as a change in the spin character of the individual components of the perturbed pair.
Two laser beams at frequencies ${\ensuremath{\nu}}_{1}$ and ${\ensuremath{\nu}}_{2}$ are used to produce nonlinear scattering (wave mixing) in
I2 vapor at frequency 2${\ensuremath{\nu}}_{1}$+${\ensuremath{\nu}}_{2}$. The scattering results from near-resonant allowed transitions in
I2 molecules and is observed to be anomalously strong when both laser beam frequencies are detuned in the same direction from frequencies corresponding to resonance in the free molecule. The strong scattering is interpreted in terms of a resonantly enhanced ac Stark shift caused by a configuration interaction between the ``dressed molecular levels.'' By tuning the two pulses simultaneously, a tuning range of approximately 2 A\r{} (50 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$) is achieved in the mixed wave. The scattering process should therefore have practical application in the efficient generation of tunable coherent radiation in the ultraviolet and vacuum-ultraviolet range of the spectrum. Some of the spectroscopic properties of the three-quantum state at E\ensuremath{\sim}53 000 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ are studied.
In recent years, coherent effects in atomic and molecular systems have been studied extensively, especially in several new classes of effects, such as lasing without inversion (LWI), electromagnetically induced transparency (EIT), coherent population trapping (CPT), AC Stark effect and Autler-Townes (AT) splitting in multilevel systems. The AC stark effect and Autler-Townes splitting in molecules have only been investigated recently. We demonstrate AC stark effect and Autler-Townes (AT) splitting in a lithium molecule using cw multi-photon spectroscopy. The excited upper level of the
G1Pig is prepared by the optical-optical double resonance (OODR) excitation. The OODR line is split in the presence of a third coupling laser, which couples the upper level to an another intermediate level when the coupling laser is on or near resonance transition. The AT line shape consists of the superposition of
∣MJ∣ components which have been resolved for
G1Pig(v=12,J=3,f). We find that the AT splittingis linearly proportional to
∣MJ∣, which allows the excitation of molecules with a selected
∣MJ∣ level. The AC Stark shift of the OODR line is observed when the coupling laser is detuned from the resonance transition.