Phase control over decaying molecular states in intense laser pulses

Pegarkov, A. I.

doi:10.1063/1.2018878

Cited by 2 publications

(1 citation statement)

References 40 publications

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“…Coherent control of molecules has been investigated extensively, − and some thought has been given to restricting dynamics in state space by coherent control. − We previously demonstrated computationally the feasibility of freezing intramolecular vibrational energy redistribution (IVR) . The idea is to prepare a nonstationary bright state (bright = optically accessible), followed by a shaped pulse to prevent that state from dephasing.…”

Section: Introductionmentioning

confidence: 99%

Freezing Vibrational Energy Flow: A Fitness Function for Interchangeable Computational and Experimental Control

2009

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We develop a fitness functional for freezing molecular energy flow that relies only on experimental observables. The functional allows us to implement a modular control algorithm where simulation data and experimental data can be used interchangeably. This interchangeability could be useful as a spectroscopic tool and for reactive control because the controllability of the experimental system and its model can be compared directly. The fitness functional performs as well as functionals based on complete knowledge of the wave function. We compare our simulation results with an analytical theory of control, and find good agreement between the simulated and predicted times over which the system can be controlled.

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Section: Introductionmentioning

confidence: 99%

Freezing Vibrational Energy Flow: A Fitness Function for Interchangeable Computational and Experimental Control

2009

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Role of the Gouy Phase in the Coherent Phase Control of the Photoionization and Photodissociation of Vinyl Chloride

Barge

Willig

2006

Phys. Rev. Lett.

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We demonstrate theoretically and experimentally that the Gouy phase of a focused laser beam may be used to control the photo-induced reactions of a polyatomic molecule. Quantum mechanical interference between one-and three-photon excitation of vinyl chloride produces a small phase lag between the dissociation and ionization channels on the axis of the molecular beam. Away from the axis, the Gouy phase introduces a much larger phase lag that agrees quantitatively with theory without any adjustable parameters.It is an axiom of quantum mechanics that the probability of an event may be calculated by adding the probability amplitudes of all independent paths connecting the initial and final states and then taking the modulus squared of that sum [1]. Because the phases of different paths vary with the parameters of the system, the transition probability displays an oscillatory pattern with respect to those parameters. Brumer and Shapiro [2] predicted that, by manipulating the appropriate parameters, an experimenter could control the outcome of the event. Their theory has been validated experimentally for numerous systems [3][4][5][6][7][8].The most commonly studied control scenario is the multiphoton excitation of a target by different numbers of photons in each path. Brumer and Shapiro showed that for the absorption of n photons of frequency ω m and m photons of frequency ω n , such that nω m = mω n , the probability of obtaining product S is given bywhere P S m is the n−photon transition probability, P S n is the m−photon probability, and P S mn is the amplitude of the interference term [9]. The interference term is given explicitly by the integralwhere |g is the ground state, |E, S,k is the excited continuum state, E andk are the energy and momentum of the excited state, and D (j) is the j-photon transition dipole operator. The phase of this term consists of a spatial component, φ sp , which is a property of the radiation field (contained in D (j) ), and a molecular component, δ The spatial phase itself has three components,where φ i is a constant phase of the electric field, z is the axial coordinate of the field, k i is the wave number, η(z) = tan −1 (z/z R ) is the Gouy phase, and z R is the Rayleigh range [14]. The first term in φ sp is proportional to the difference between the refractive indices at frequencies ω m and ω n [15]. The second term is usually assumed to vanish because of momentum conservation (although see ref.[16] for a possible counter-example). The Gouy phase shift in the third term results from the increased phase velocity of a Gaussian beam, as compared with a plane wave, as it propagates through a focal region [17], [18], [19]. More generally, it has been shown that the Gouy phase results from a spread in the transverse momentum of the focused beam [20]. This phase does not appear in Brumer and Shapiro's formulation, presumably because it is not explicitly channel-dependent. Chen and Elliott [21] demonstrated that the modulation of the signal produced by one-and three-photon ionization of m...

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Phase control over decaying molecular states in intense laser pulses

Cited by 2 publications

References 40 publications

Freezing Vibrational Energy Flow: A Fitness Function for Interchangeable Computational and Experimental Control

Freezing Vibrational Energy Flow: A Fitness Function for Interchangeable Computational and Experimental Control

Role of the Gouy Phase in the Coherent Phase Control of the Photoionization and Photodissociation of Vinyl Chloride

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