Optical Stark effect

External electric field applied to a medium shifts the energy levels. It results in a change of absorption spectrum (blue shift) and this phenomenon is called DC or AC Stark effect. The same effect one observes at optical frequencies. The shift of optical absorption spectrum is 

The magnitude of absorption shift depends on the detuning energy i.e. the difference between pump and one photon allowed transition energy and is proportional to the square of applied electric field. Within the three level model the frequency shift of absorption spectrum (cf. Charra and Nunzi (1989)) is given by 

Using this model and E, values from linear optical absorption and THG measurements (Messier (1989))f Charra and Nunzi (1989)) have determined from optical Stark effect measurements on poly- BCMU blue and red gels the ratio of dipolar transition moments follows that 

Blanchard et al. studied optical Stark effect in PTS single crystal film as a function of detuning energy AE = - w. At small values the optical Stark effect is phonon mediated because of strong exciton-phonon coupling in these materials. At large it is mainly excitonic Stark effect. 

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Mark s contributions while at the I. G. were not limited to the emerging field of polymer science. In those five years, he also took part in studies of X-ray optics and continued his study of the X-ray structure of metals and metal salts. Other seemingly unrelated paper were published on the width of X-ray emission lines (12), Schlenk isomerism (13), the structure of aromatic compounds (14), and a special "hobby" the optical Stark Effect (15, 16). Regarding this latter work, Mark relates that his supervisors tolerated the research commenting that "as long as they are doing something decent and important" it was okay "as sport doesn t cost much money". 

The autput of a mode-locked ruby laser 729) producing a train of pulses of 5 psec duration with a maximum peak power of 5 GW was focused into a cell pressurized with the sample gas. Pulse-energy conversion efficiencies into the Raman lines of up to 70 % have been obtained. The induced rotational lines are broadened this could be due to a strong optical Stark effect 730)... 

I. Is it possible to observe a shift in coherent Raman scattering in the three-level system with A-type coupling We have done an experiment to obtain a femtosecond Raman gain spectrum in polydiacetylenes. The Raman spectrum is shifted to the red under increased pump (to i) intensity. By changing o>2> the amplification peak signal is to be shifted to lower frequency. If the optical Stark effect is observed, then, in principle, it should be possible to observe the effect of a high field on the coherent Raman spectrum (see Fig. 1). 

Though I do not wish to reiterate the well known history of polymer science, it is worthwhile emphasizing that these two industrial scientists made important contributions to pure science, as they had intended. They investigated fundamental questions concerning the constitution of polymers, without envisaging any immediate use of their work in industry. Moreover, Mark and his collaborators had the opportunity to do scientific work that was not connected with polymers and metals. They published papers on the width of x-ray emission lines, the optical Stark effect, molecular structure... 

Becker, P.C., Fork, RiL., Brito Cruz, C.H., Gradrai, J.P., Shank, C.V. Optical Stark effect in organic dyes probed with optieal pulses of 6 fs duration. Phys. Rev. Lett. 60, 2462-2464 (1988)... 

S.K., Krasinski, J.S., Song, (.(. and Chang, Yia-Chimg (2002) Polarization dependence of the exdtonic optical Stark effect in GaN. Physical Review B ... 

CHARRA F. and NUNZI J.M., (1989a), "Picosecond Studies of Optical Stark Effect in Polydiacetylene", in Nonlinear Optical Effects in Organic Polymers, J. Messier, F. Kajzar, P. Prasad and D. Ulrich eds., NATO ASI Series, Vol. 162, Kluwer Academic Publ. Dordrecht, 369 371 ... 

Tamarat P, Lounis B, Bernard J, Orrit M, Kummer S, Kettner R, Mais S and Basche T 1995 Pump-probe experiments with a single molecule ac-Stark effect and nonlinear optical response Phys. Rev. Lett. 75 1514-17... 

Kuhn B, Fromherz P (2003) Anellated hemicyanine dyes in a neuron membrane Molecular Stark effect and optical voltage recording. J Phys Chem B 107(31) 7903—7913... 

The Stark effect is electric-field-induced change in optical transition energy of materials, and the effect is observed as spectral change in absorption due to the energy shift. In the linear Stark effect, energy shift of optical transition Av in proportion to the electric field F is presented by... 

As mentioned in this section, the linear Stark effect measurement provides detailed information on noncentrosymmetric molecular orientation. This technique is very helpful for the advanced molecular design of noncentrosymmetric LB films for electro-optic and nonlinear optic applications. 

Electro-optical effects (Stark effects) of CdS nanocrystallites were investigated 107,108,109... 

The reason that I am elaborating in such detail on these c.t.s. s is that they are practically the only states in region 3, and also I believe that if we can only get a clear understanding of these states, the question of optical transition will sort itself out automatically. There are also many other effects in molecular complexesjyhere the c.t.s. s enter. I have already mentioned the cases of the quadratic Stark effect and of tfie asymmetric crystal field, where the c.t.s. s must be allowed to play an equally important and indeed analogous role. A further effect relates to the width of the charge transfer bands. The main cause of the breadth is essentially the same as that for the width of the crystal-field spectrum, except that it is much... 

Significant differences in the optical signatures of Eu3+ ions were observed between GaN Eu QDs and GaN Eu layers (Andreev et al., 2005b) (1) the emission fine at 633.5 was not observed in GaN Eu QDs for unknown reason (2) the 5Do 7F2 transition was red shifted by 1.7 nm in QDs compared to the layer sample, which could be induced by a strong internal electric filed in QDs (quantum confinement Stark effect) (3) the PL intensity is almost temperature independent for GaN Eu QDs, but sensitive to temperature for GaN Eu layers (Hori et al., 2004). 

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). 

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

In the "nonrigid symmetric-top rotors" (such as NH ), the second-order Stark effect is observed under normal circumstances. Indeed, field strengths of the order of 1 600 000 [V/m] are required to bring the interaction into the first-order regime in this case [18]. In contrast, very weak interactions suffice to make the mixed-parity states and appropriate for the description of optically active systems. Parity-violating neutral currents have been proposed as the interaction missing from the molecular Hamiltonian [Eq.(1)] that is responsible for the existence of enantiomers [14,19]. At present, this hypothesis is still awaiting experimental verification. 

This theory has revealed a powerful tool for the interpretation of a wide class of phenomena, including the optical rotatory power, the refractive index and the stopping power of gases, the Stark effect, the long-range intermol-ecular forces, and so on,... 

It was previously demonstrated theoretically [1] and experimentally [2] that semiconductor quantum dots (QDs) show strong dependence of optical properties on an electric field. Chemically synthesized semiconductor nanorods also exhibit the electric field effects. For example, quantum-confined Stark effect and luminescence quenching of single nanorods were previously demonstrated [3-5]. Unlike QDs, the nanorods exhibit quantum confinement only in two dimensions. It is reasonable to assume that the electric field applied along a nanorod may result in the strong polarization dependence of photoluminescence (PL). In the present paper, we investigate the influence of an external electric field onto luminescent properties of chemically synthesized CdSe/ZnS nanorods. 

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