Dynamic Stark effect

A cut along the pump laser frequency axis for a nonresonant dump laser frequency yields REMPI spectra. The same cut for a resonant dump laser frequency show a splitting of the 2 < - 1 transition that can be explained in the intuitive picture of a dynamic Stark effect. (For a closer discussion of this point, see Refs. 6 and 30). A cut along the dump laser frequency... 

The second term describes the influence of the dynamic Stark effect leading to a shift in the resonance frequency of the molecular transition by the value... 

The system of equations obtained, (5.22) and (5.23), in broad line approximation in many cases allows us to carry out the analysis of non-linear optical pumping of both atoms and molecules in an external magnetic field. Some examples will be considered in Section 5.5, among them the comparatively unexplored problem of transition from alignment to orientation under the influence of the dynamic Stark effect. But before that we will return to the weak excitation and present, as examples, some cases of the simultaneous application of density matrix equations (5.7) and expansion over state multipoles (5.20). 

The E-vector action of a sufficiently intensive light, which may be considered as a source of the dynamic Stark effect (us 7 0) can also induce orientation of particles. Such alignment-orientation conversion in the depopulated ground state in the presence of a magnetic field will be discussed in Section 5.5... 

In the case of strong excitation, in addition to the effects considered in Section 5.4, under the action of the dynamic Stark effect, transition from alignment to orientation may also take place [36, 243], which means that polarization moments of odd rank may emerge. This manifests itself in the second order of the expansion. Thus, we have... 

An analysis of Eqs. (5.71) and (5.72) shows that orientation of the ground (initial) level J" emerges only under conditions of the dynamic Stark effect, when us 0, and at non-zero angle between the magnetic field B and the light vector E (see Fig. 5.8). The shape of the dependence... 

In all three cases, we obtain lA22 J// 1 at large J" values. Thus, the effect of transition from alignment to orientation under the action of the dynamic Stark effect is a purely quantum mechanical phenomenon and disappears at J — oo. 

Owing to the coincidence between a number of coefficients, the symmetry of the equations obtained is considerably higher, as compared to (5.22) and (5.23). In addition, the terms responsible for the dynamic Stark effect disappear, which agrees perfectly with the analysis performed in the preceding section concerning the influence of the dynamic Stark effect on optical polarization of molecules. 

Auzinsh, M.P. (1990). On the possibility of experimental observation of the dynamic Stark effect influence on the laser induced fluorescence of dimers, Optika i Spektroskopiya, 69, 302-306. [Opt. Spectrosc. (USSR), 69, 182-185]. 

Auzinsh, M.P. (1992). Dynamic Stark effect action on optical pumping of atoms in an external magnetic field, Phys. Lett. A, 169, 463—468. 

Volk M, Kholodenko Y, Lu HSM, Gooding EA, DeGrado WF, Hochstrasser RM. Peptide conformational dynamics and vibrational Stark effects following photoinitiated disulfide cleavage. J Phys Chem B 1997 101 8607-8616. 

Keywords Autler-Townes effect, dynamic Stark shift, molecular spectra... 

Krylovetsky,A. A.jManakov, N. L., Marmo, S. I. (1997). Quadratic stark effect and dipole dynamic polarizabilities of hydrogen-hke levels. Laser Phys. 1,781-796. 

Problem of the light-shifts. Another important point to discuss now is what is called the dynamical Stark effect of light shifts. These light shifts are well understood since the pioneering work of Cohen-Tannoudji in 1962 38. They are caused by every non-resonant irradiatior of the atoms, as we have in the intermediate steps of each multiphoton transition. 

Ultrashort pulses may be also used for vibrational spectroscopy with high frequency resolution. As a first example we have demonstrated FT-CARS of a supersonic expansion. Several advantages of the technique should be noted. The effect of transit time broadening can be eliminated. Artifacts via the nonresonant part of the third order susceptibility are negligible. A possible dynamic Stark effect during the excitation process does not influence the ns signal transient. Precise spectroscopic information is provided without narrow-band laser sources. 

Nonadiabatic electronic transitions are of fundamental importance in chemistry. In particular, because a conical intersection (conical intersection) between two electronic states provides a very fast and efficient pathway for radiationless relaxation [117], there has been much interest in controlling transitions through a conical intersection. Indeed, several methods have already been proposed to control the dynamical processes associated with a conical intersection. One of these concerns the modification of electronic states involved in the conical intersection by environmental effects of polar solvents on the PES (potential energy hypersurface) through orientational fluctuations [6, 67, 68]. Another strategy is to apply a static electric field to shift the energy of a state of ionic character as in the Stark effect ]384, 482] (see Ref. ]403, 404] for the non-resonant dynamical Stark effect). More dynamical methods, which aim to suppress the transition either by preparing... 

Laser Control of the Radiationless Decay in Pyrazine Using the Dynamic Stark Effect... 

In Chap.5, we showed that the dark Auirnr ) state plays an important role in the photophysics of pyrazine. However, in the present work, we consider a simpler model including only the bright B uinn ) and B2u(Tnr ) states and the four most important vibrational modes of the molecule. Similar models have been considered in a number of previous investigations of the non-adiabatic dynamics of the molecule [31, 32] and its conttol by laser pulses [22, 25, 26]. Therefore, while this model can not fully account for the complexity of the dynamics of photoexcited pyrazine, it allows us to compare our control mechanism with alternative control mechanisms proposed in previous studies. In addition, the results presented in this chapter are of general interest for the laser control of radiationless decay processes using the dynamic Stark effect. 

This attractive feature makes this class of control mechanisms a promising candidate for the laser control of non adiabatic dynamics in polyatomic molecules. Despite this, much work will be necessary to further assess the applicability of control mechanisms based on the Stark effect to a wide class of systems. 

---