Stark switching

Fig. 19.7 Schematic diagram of the Stark switching technique applied to n = 7 Rydberg states. The arrow shows laser excitation of the Stark state in the field Eg. The field is then reduced to zero adiabatically to produce the Z = 5 state. The zero field separations of the Z...

Autoionization rates also decrease rapidly with (, a point first shown experimentally by Cooke etal.n who measured the autoionization rates of the Sr 5pl5 states of = 2-7. The t>2 states were populated using the Stark switching... 

The microwave detected MODR scheme closely resembles pulsed nuclear magnetic resonance (Hahn, 1950), optical coherent transients by Stark switching (Brewer and Shoemaker, 1971) and laser frequency switching (Brewer and Genack, 1976). The on-resonance microwave radiation field, ojq = ( 2 — Ei)/H, creates an oscillating bulk electric dipole polarization (off-diagonal element of the density matrix, pi2(t)). The oscillation is at u>o u>r, where ojr is the (Mj-dependent) Rabi frequency,... 

Fig. 7.23 (a) Stark switching technique for the case of a Doppler-broadened molecular transition. 

Figure 7.23 illustrates the Stark switching technique, which can be applied to all those molecules that show a sufficiently large Stark shift [908]. In the case of Doppler-broadened absorption lines the laser of fixed frequency initially excited molecules of velocity v. A Stark pulse, which abruptly shifts the molecular ab-... 

Fig. 12.20. (a) Stark switching technique for the case of a Doppler-broadened molecular transition, (b) Infrared photon echo for a vibration-rotation transition. The... 

Figure 12.20 illustrates the Stark switching technique, which can be applied to all those molecules that show a sufficiently large Stark shift... 

Fig. 12.20. (a) Stark-switching technique for the case of a Doppler-broadened molecular transition, (b) Infrared photon echo for a CH3p vibration-rotation transition. The molecules are switched twice into resonance with a CW CO2 laser by the two Stark pulses shown in the lower trace. The 3rd pulse is the photon echo [12.63]... 

Using the Stark switching technique with varying pulse delay times in an... 

Fig.11.31. Fourier transform heterodyne beat spectrum of CH3F derived from Stark switched two-pulse photon echoes [11.491...

Electronic excitation of the chromophore is simulated by instantly switching the charges (and in some studies also the geometry) on the QM system to excited state (Sj) values. Most of the internal Stark effect (ISE) is expressed implicitly by the difference of the potentials at different atoms. 

Figure 6.9 Generic five-state system for ultrafast efficient switching. The resonant two-state system of Figure 6.6 is extended by three target states for selective excitation. While the intermediate target state 4) is in exact two-photon resonance with the laser pulse, both outer target states 3) and 5) lie well outside the bandwidth of the two-photon spectrum. Therefore, these states are energetically inaccessible under weak-field excitation. Intense femtosecond laser pulses, however, utilize the resonant AC Stark effect to modify the energy landscape. As a result, new excitation pathways open up, enabling efficient population transfer to the outer target states as well.

The combustion velocities given in Table 13.4 show that the use of nano CuO is more of a factor towards high velocities than the Al when the Al is highly oxidized, and even slightly decreases performance when the velocity of pm-CuO / pm-A1 is compared to pm-CuO / nm-Al. The mass burning rate shows this even more starkly, as with a given particle size of CuO, the switch from micron to heavily oxidized nano aluminum decreases the mass burning rate. 

In the following, we describe in detail the case of Fig. 8. For the process in A or ladder systems, where the initial population resides in state 1), two different adiabatic paths lead to the complete population transfer, depending on the pulse sequence. The path denoted (a) corresponds to an intuitive sequence for the rise of the pulses. The pump pulse is switched on first, making the levels connected to the states 1) and 2) repel each other (dynamical Stark shift) until the level connected to 11) crosses the level connected to 3). The Stokes pulse is switched on after the crossing. Next the two pulses can decrease in any order. Path (b) is associated to a counterintuitive sequence for the decrease of the pulses. The two... 

Thus far, studies of coherent optical processes in a PBG have assumed fixed (static) values of the atomic transition frequency [Quang 1997], However, in order to operate quantum logic gates, based on pairwise entanglement of atoms by field-induced dipole-dipole interactions [Brennen 1999 Petrosyan 2002 Opatrny 2003], one should be able to switch the interaction on- and off-, most conveniently by AC Stark-shifts of the transition frequency of one atom relative to the other, thereby changing its detuning from the PBG edge. 

This result is in stark contrast to a study of Moyna et alf who applied nearly the same formalism for calculating the proton chemical shifts [Eq. (40)]. For the tripeptide under investigation only a limited set of intra-residue proton distances was available. The definition of structure was therefore greatly improved when the proton chemical shift constraints were switched on. The chemical shift refinement reduced the rmsd for the backbone atoms from 1.2 A to 0.2 A, and it revealed a single set of conformers with both peptide bonds in trans conformation. The shift constraints drove the molecule energetically uphill by 3.9 kcal/mol but produced a well-defined minimum within the energy hyper-surface. Obviously, chemical shift constraints will produce well-defined structures when other constraints are not available from experiment. 

We normally always start by trying to achieve compliance at the lowest frequency, that is, fsw- But if the switching frequency drops below 500 kHz, certain factors start working starkly in our favor, and some against. We will discover that soon. 

Fig. 1.3. This figure shows a small section of the rotational spectrum of ethyleneoxide in the presence of a magnetic field of 25.672 kG. A Stark effect modulated microwave spectrometer operated with AM = 0 selection rule was used for this recording, which actually consists of two superimposed absorption spectra. One of these spectra is observed in the absence of the modulating Stark field (above the horizontal line) and the other is observed during the periods when the modulating field is switched on (below the horizontal line). In most investigations only the upper part (pure Zeeman effect) is used for the analysis, since calibration uncertainties and the inhomogoneity of the modulating Stark-field lead to a reduced accuracy of Zeeman data derived from the splittings observed in the simultaneous presence of both fields...

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