Dynamic Stark control

For dynamics of even shorter durations, when the frequency of the external field is such that the time scale of the oscillation of the field is comparable to the time scale of nuclear dynamics, it may be better to regard the potential surfaces as becoming time-dependent through including the interaction potential within them [355]. The potential surfaces time-evolve not only with the envelope function of the external field but follows the oscillation of the external field itself, enabling dynamic Stark control [404]. 

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. 

M. Sala, M. Saab, B. Lasome, F. Gatti and S. Guerin, Laser control of the radiationless decay in pyrazine using the dynamic Stark effect , J. Chem. Phys. 140, 194309 (2014)... 

While the formalism of DD is quite different from the formalism presented here, it can be easily incorporated into the general framework of universal dynamical decoherence control by introducing impulsive PM. Let the phase of the modulation function periodically jump by an amount 4> at times r, 2t,. .. Such modulation can be achieved by a train of identical, equidistant, narrow pulses of nonres-onant radiation, which produce pulsed AC-Stark shifts of co. When (/> = tt, this modulation corresponds to DD pulses. 

In stark contrast with most other pharmacologic delivery methods (e.g., pills, intravenous), there is little control on what amount of drug is actually delivered to the target tissue (i.e., the ocular surface) when a physician prescribes a topical formulation. To overcome this problan, investigators have attempted to deliver medications by spraying the drug onto the eye, but initial efforts with such systems as atomizer sprays have failed due to the inability to control droplet size and flow dynamics for consistent and predictable administration. Major problans related to the physics of droplet ejection, such as dispersion, droplet evaporation, drag, and non-coUimated flow turbulence, have held back such new approaches until recently. ... 

The symmetries of wavepackets viewed on a progressively finer scale offer a temperature-robust way of encoding several qubits of information [62-64], The encoding and often the full control over the quantum evolution of the wavepacket [65] can be implemented by alternating periods of free motion with phase kicks imposed by coordinate-dependent Stark shifts. Distinguishing odd from even wave forms is the essence of the decoding of the qubits of information encoded in the wavefunction by the dynamics of atoms in a trap. The calculations below demonstrate the possibility to distinguish between the even wave form/(°+) and the odd onef K... 

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. 

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