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K Jungmann - One of the best experts on this subject based on the ideXlab platform.

  • resonant three photon ionization of hydrogenic atoms by a non Monochromatic Laser field
    Journal of Physics B, 1999
    Co-Authors: V Yakhontov, Robin Santra, K Jungmann
    Abstract:

    We present ionization probability and lineshape calculations for the two-step three-photon ionization process, , of the ground state of hydrogenic atoms in a non-Monochromatic Laser field with a time-dependent amplitude. Within the framework of a three-level model, the AC Stark shifts and non-zero ionization rates of all states involved were taken into account, together with spatial and temporal inhomogeneities of the Laser signal. In contrast with the usual perturbative technique, the time evolution of the atomic states was simulated by directly solving the system of coupled time-dependent inhomogeneous differential equations numerically, the equations being equivalent to the appropriate non-stationary Schrodinger equation. Particular numerical results were obtained for typical parameters of the pulsed Laser field that are employed in a new experiment to measure the 1S-2S energy separation with muonium at the Rutherford Appleton Laboratory. The shifts and asymmetries of the photoionization lineshapes revealed may be of relevance for ultra-high-precision experiments in hydrogen in CW Laser fields.

  • Resonant 3--photon ionization of hydrogenic atoms by non-Monochromatic Laser field
    Journal of Physics B: Atomic Molecular and Optical Physics, 1999
    Co-Authors: Yakhontov, Robin Santra, K Jungmann
    Abstract:

    We present ionization probability and line shape calculations for the two-step 3-photon ionization process, $1S \stackrel{2\hbar \omega}{\longrightarrow}2S \stackrel{\hbar \omega}{\longrightarrow}\epsilon P $, of the ground state of hydrogenic atoms in a non-Monochromatic Laser field with a time--dependent amplitude. Within the framework of a three--level model, the {\it AC Stark} shifts and non-zero ionization rates of all states involved were taken into account together with spatial and temporal inhomogeneities of the Laser signal. In contrast with the usual perturbative technique, the time evolution of the atomic states was simulated by direct numerically solving the system of coupled time--dependent inhomogeneous differential equations, being equivalent to the appropriate non-stationary Schr\"{o}dinger equation. Particular numerical results were obtained for typical parameters of the pulsed Laser field that are employed in a new experiment to measure the $1S-2S$ energy separation in muonium at the Rutherford Appleton Laboratory. The shifts and asymmetries of the photoionization line shapes revealed may be of relevance for ultra-high precision experiments in hydrogen in CW Laser fields.

Davide Donadio - One of the best experts on this subject based on the ideXlab platform.

  • simulating energy relaxation in pump probe vibrational spectroscopy of hydrogen bonded liquids
    Journal of Chemical Theory and Computation, 2017
    Co-Authors: Riccardo Dettori, Michele Ceriotti, Johannes Hunger, Claudio Melis, Luciano Colombo, Davide Donadio
    Abstract:

    We introduce a nonequilibrium molecular dynamics simulation approach, based on the generalized Langevin equation, to study vibrational energy relaxation in pump–probe spectroscopy. A colored noise thermostat is used to selectively excite a set of vibrational modes, leaving the other modes nearly unperturbed, to mimic the effect of a Monochromatic Laser pump. Energy relaxation is probed by analyzing the evolution of the system after excitation in the microcanonical ensemble, thus providing direct information about the energy redistribution paths at the molecular level and their time scale. The method is applied to hydrogen-bonded molecular liquids, specifically deuterated methanol and water, providing a robust picture of energy relaxation at the molecular scale.

  • simulating energy relaxation in pump probe vibrational spectroscopy of hydrogen bonded liquids
    Journal of Chemical Theory and Computation, 2017
    Co-Authors: Riccardo Dettori, Michele Ceriotti, Johannes Hunger, Claudio Melis, Luciano Colombo, Davide Donadio
    Abstract:

    We introduce a nonequilibrium molecular dynamics simulation approach, based on the generalized Langevin equation, to study vibrational energy relaxation in pump–probe spectroscopy. A colored noise thermostat is used to selectively excite a set of vibrational modes, leaving the other modes nearly unperturbed, to mimic the effect of a Monochromatic Laser pump. Energy relaxation is probed by analyzing the evolution of the system after excitation in the microcanonical ensemble, thus providing direct information about the energy redistribution paths at the molecular level and their time scale. The method is applied to hydrogen-bonded molecular liquids, specifically deuterated methanol and water, providing a robust picture of energy relaxation at the molecular scale.

Riccardo Dettori - One of the best experts on this subject based on the ideXlab platform.

  • simulating energy relaxation in pump probe vibrational spectroscopy of hydrogen bonded liquids
    Journal of Chemical Theory and Computation, 2017
    Co-Authors: Riccardo Dettori, Michele Ceriotti, Johannes Hunger, Claudio Melis, Luciano Colombo, Davide Donadio
    Abstract:

    We introduce a nonequilibrium molecular dynamics simulation approach, based on the generalized Langevin equation, to study vibrational energy relaxation in pump–probe spectroscopy. A colored noise thermostat is used to selectively excite a set of vibrational modes, leaving the other modes nearly unperturbed, to mimic the effect of a Monochromatic Laser pump. Energy relaxation is probed by analyzing the evolution of the system after excitation in the microcanonical ensemble, thus providing direct information about the energy redistribution paths at the molecular level and their time scale. The method is applied to hydrogen-bonded molecular liquids, specifically deuterated methanol and water, providing a robust picture of energy relaxation at the molecular scale.

  • simulating energy relaxation in pump probe vibrational spectroscopy of hydrogen bonded liquids
    Journal of Chemical Theory and Computation, 2017
    Co-Authors: Riccardo Dettori, Michele Ceriotti, Johannes Hunger, Claudio Melis, Luciano Colombo, Davide Donadio
    Abstract:

    We introduce a nonequilibrium molecular dynamics simulation approach, based on the generalized Langevin equation, to study vibrational energy relaxation in pump–probe spectroscopy. A colored noise thermostat is used to selectively excite a set of vibrational modes, leaving the other modes nearly unperturbed, to mimic the effect of a Monochromatic Laser pump. Energy relaxation is probed by analyzing the evolution of the system after excitation in the microcanonical ensemble, thus providing direct information about the energy redistribution paths at the molecular level and their time scale. The method is applied to hydrogen-bonded molecular liquids, specifically deuterated methanol and water, providing a robust picture of energy relaxation at the molecular scale.

Hui Cao - One of the best experts on this subject based on the ideXlab platform.

  • Customizing Speckle Intensity Statistics
    Optica, 2018
    Co-Authors: Nicholas Bender, Hasan Yılmaz, Yaron Bromberg, Hui Cao
    Abstract:

    Speckles commonly satisfy Rayleigh statistics. However, in many applications, non-Rayleigh speckles with customized intensity statistics are desirable. Here, we present a general method for customizing the intensity statistics of speckle patterns on a target plane. By judiciously modulating the phase front of a Monochromatic Laser beam, we experimentally generate speckle patterns with arbitrarily tailored intensity probability density functions. Relative to Rayleigh speckles, our customized speckles exhibit radically different topologies yet maintain the same spatial correlation length. The customized speckles are fully developed, ergodic, and stationary–with circular non-Gaussian statistics for the complex field. Propagating away from the target plane, the customized speckles revert back to Rayleigh speckles. This work provides a versatile framework for tailoring speckle patterns with varied applications in microscopy, imaging, and optical manipulation.

  • customizing speckle intensity statistics
    arXiv: Optics, 2017
    Co-Authors: Nicholas Bender, Hasan Yılmaz, Yaron Bromberg, Hui Cao
    Abstract:

    We develop a general method for customizing the intensity statistics of speckle patterns. By judiciously modulating the phase-front of a Monochromatic Laser beam, we experimentally generate speckle patterns with arbitrarily-tailored intensity probability-density functions (PDF). Based on applying a local intensity transformation to a Rayleigh speckle pattern, our method allows for topological changes in the customized speckles while preserving their granularity. In addition to tailoring the functional form of the intensity distribution, we can separately control the intensity range of the PDF and thereby tune the speckle contrast.

Robin Santra - One of the best experts on this subject based on the ideXlab platform.

  • resonant three photon ionization of hydrogenic atoms by a non Monochromatic Laser field
    Journal of Physics B, 1999
    Co-Authors: V Yakhontov, Robin Santra, K Jungmann
    Abstract:

    We present ionization probability and lineshape calculations for the two-step three-photon ionization process, , of the ground state of hydrogenic atoms in a non-Monochromatic Laser field with a time-dependent amplitude. Within the framework of a three-level model, the AC Stark shifts and non-zero ionization rates of all states involved were taken into account, together with spatial and temporal inhomogeneities of the Laser signal. In contrast with the usual perturbative technique, the time evolution of the atomic states was simulated by directly solving the system of coupled time-dependent inhomogeneous differential equations numerically, the equations being equivalent to the appropriate non-stationary Schrodinger equation. Particular numerical results were obtained for typical parameters of the pulsed Laser field that are employed in a new experiment to measure the 1S-2S energy separation with muonium at the Rutherford Appleton Laboratory. The shifts and asymmetries of the photoionization lineshapes revealed may be of relevance for ultra-high-precision experiments in hydrogen in CW Laser fields.

  • Resonant 3--photon ionization of hydrogenic atoms by non-Monochromatic Laser field
    Journal of Physics B: Atomic Molecular and Optical Physics, 1999
    Co-Authors: Yakhontov, Robin Santra, K Jungmann
    Abstract:

    We present ionization probability and line shape calculations for the two-step 3-photon ionization process, $1S \stackrel{2\hbar \omega}{\longrightarrow}2S \stackrel{\hbar \omega}{\longrightarrow}\epsilon P $, of the ground state of hydrogenic atoms in a non-Monochromatic Laser field with a time--dependent amplitude. Within the framework of a three--level model, the {\it AC Stark} shifts and non-zero ionization rates of all states involved were taken into account together with spatial and temporal inhomogeneities of the Laser signal. In contrast with the usual perturbative technique, the time evolution of the atomic states was simulated by direct numerically solving the system of coupled time--dependent inhomogeneous differential equations, being equivalent to the appropriate non-stationary Schr\"{o}dinger equation. Particular numerical results were obtained for typical parameters of the pulsed Laser field that are employed in a new experiment to measure the $1S-2S$ energy separation in muonium at the Rutherford Appleton Laboratory. The shifts and asymmetries of the photoionization line shapes revealed may be of relevance for ultra-high precision experiments in hydrogen in CW Laser fields.