Stark effect level shift

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). 

An external electric field leads to three alterations in the electron structure of an atom. Firstly, the energy levels of the atom are shifted and split (the Stark effect). The theory of this effect is well-known [8], Secondly, the highly excited states of the atom disappear. The potential for the outer electron of the highly excited atom, is equal to... 

When a) l/n3, the field required for ionization is E = 1/9n4, and as a> approaches l/n3 it falls to E=0.04n. These observations can be explained qualitatively in the following way. At low n, so that a> 1/n3, the microwave field induces transitions between the Stark states of the same n and m by means of the second order Stark effect. With only a first order Stark shift a state always has the same dipole moment and wavefunction, as indicated by the constant slope dW/d of the energy level curve. Thus when the field reverses, — — , the Rydberg electron s orbit does not change. With a second order Stark shift as well, the slope dW/d is not the same at E and —E, and as a result the dipole moment and wavefunction are not the same. If the field is reversed suddenly a single Stark state in the field E is projected onto several Stark states of the same n and m when E — - E. Since all the Stark states of the same n make transitions among themselves they ionize once the field is adequate to ionize one of them, the red one, at E = 1/9n4 for m n. 

We have calculated exactly the Zeeman effect for the levels IS, 3S and 3P. Indeed it is necessary to know the shift for all the hyperfine levels very well. These calculations are very classical and we just present the results in a Zeeman diagram (see Fig. 5). The most important part in the diagram is the crossing between the 38 2 (F=l, mp=-l) and 3P1/2(F=1, mj =0) levels, because the quadratic Stark effect is proportional to the square of the induced electric field and inversely proportional to the difference of energy between the two considered levels. Moreover the selection rules for the quadratic Stark effect in our case (E perpendicular to B) impose Am.F= l. So it is near this crossing that the motional Stark shift is large enough to be measured. In our calculations the Stark effect is introduced by the formalism of the density matrix [4] where the width of the levels are taken into account. The result of the calculation presented on... 

Meerts and Dymanus [142, 153] extended their studies of the OH and SH radicals by examining the Stark effect and determining the electric dipole moments, but an even more extensive study of the Stark effect for OH and OD in several different vibrational levels was described by Peterson, Fraser and Klemperer [154], The effect of an applied electric field on the hyperfine components of the A-doublets for the. 7 = 3 /2 level of the 2n3/2 state is illustrated in figure 8.47. Measurements were made of the MF = 2, A MF = 0 transition in a calibrated electric field of approximately 700 V cnr1 and the Stark shift from the zero-field line position measured. The observations were made on resonances from 0 = 0, I and 2 for OH, and v = 0 and 1 for OD. 

Figure 10.5. Stark effect and line shift for a two-level system.

The Stark effect on the magnetic fine structure occurs as a result of disturbance of atomic levels under the influence of the relativistic and correlation effects as well as the interaction with external electric field F. If the fields are weak enough the centre of multiplet is shifted and there occurs the splitting of sublevels of atomic multiplet n, L, J. The dipole moment induced in an atom by a uniform electric field F is for most purposes expressed as a linear function of F, but higher... 

The Stark effect is related to a change in energy levels of atoms and molecules in the presence of a strong external electric field and is observed as a shift and splitting of the spectral rotational lines. The applicability of the method is restricted to the gas phase and more complex compounds require the use of isotopically labeled molecules [43,44,50-52]. 

In Section 1.3 the shift of the single molecule excitation line under the influence of a static electric field, the DC Stark effect, is discussed. The interaction of molecular electronic energy levels with a strong optical field is also expected to lead to level shifts and splittings and additionally to a change of relaxation rates. The shift of energy levels under optical excitation is called light shift or AC Stark effect where... 

In the case of measurements at a cavity temperature of 2K [15], a reduction of the signal could be clearly seen for atomic fluxes as small as 800 atoms/s. An increase in flux caused power broadening and finally an asymmetry and a small shift (Fig. A). This shift is attributed to the ac Stark effect, caused predominantly by virtual transitions to the 6ld level, which is only 50MHz away from the maser transition (Fig. 3). the fact that the field ionization signal at resonance is independent of the particle flux (between 800 and 22 x 10 atoms/s) indicates that the transition is saturated. This, and the observed power broadening show that there is a multiple exchange of photons between Rydberg atoms and the cavity field. 

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