The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform

Kevin J Kubarych - One of the best experts on this subject based on the ideXlab platform.

  • monitoring Equilibrium Reaction dynamics of a nearly barrierless molecular rotor using ultrafast vibrational echoes
    Journal of Chemical Physics, 2014
    Co-Authors: Ian A. Nilsen, Derek G. Osborne, Aaron M. White, Jessica M. Anna, Kevin J Kubarych
    Abstract:

    Using rapidly acquired spectral diffusion, a recently developed variation of heterodyne detected infrared photon echo spectroscopy, we observe ∼3 ps solvent independent spectral diffusion of benzene chromium tricarbonyl (C6H6Cr(CO)3, BCT) in a series of nonpolar linear alkane solvents. The spectral dynamics is attributed to low-barrier internal torsional motion. This tripod complex has two stable minima corresponding to staggered and eclipsed conformations, which differ in energy by roughly half of kBT. The solvent independence is due to the relative size of the rotor compared with the solvent molecules, which create a solvent cage in which torsional motion occurs largely free from solvent damping. Since the one-dimensional transition state is computed to be only 0.03 kBT above the higher energy eclipsed conformation, this model system offers an unusual, nearly barrierless Reaction, which nevertheless is characterized by torsional coordinate dependent vibrational frequencies. Hence, by studying the spectr...

  • Monitoring Equilibrium Reaction dynamics of a nearly barrierless molecular rotor using ultrafast vibrational echoes
    Journal of Chemical Physics, 2014
    Co-Authors: Ian A. Nilsen, Derek G. Osborne, Aaron M. White, Jessica M. Anna, Kevin J Kubarych
    Abstract:

    Using rapidly acquired spectral diffusion, a recently developed variation of heterodyne detected infrared photon echo spectroscopy, we observe ∼3 ps solvent independent spectral diffusion of benzene chromium tricarbonyl (C6H6Cr(CO)3, BCT) in a series of nonpolar linear alkane solvents. The spectral dynamics is attributed to low-barrier internal torsional motion. This tripod complex has two stable minima corresponding to staggered and eclipsed conformations, which differ in energy by roughly half of kBT. The solvent independence is due to the relative size of the rotor compared with the solvent molecules, which create a solvent cage in which torsional motion occurs largely free from solvent damping. Since the one-dimensional transition state is computed to be only 0.03 kBT above the higher energy eclipsed conformation, this model system offers an unusual, nearly barrierless Reaction, which nevertheless is characterized by torsional coordinate dependent vibrational frequencies. Hence, by studying the spectral diffusion of the tripod carbonyls, it is possible to gain insight into the fundamental dynamics of internal rotational motion, and we find some evidence for the importance of non-diffusive ballistic motion even in the room-temperature liquid environment. Using several different approaches to describe Equilibrium kinetics, as well as the influence of reactive dynamics on spectroscopic observables, we provide evidence that the low-barrier torsional motion of BCT provides an excellent test case for detailed studies of the links between chemical exchange and linear and nonlinear vibrational spectroscopy.

Ian A. Nilsen - One of the best experts on this subject based on the ideXlab platform.

  • monitoring Equilibrium Reaction dynamics of a nearly barrierless molecular rotor using ultrafast vibrational echoes
    Journal of Chemical Physics, 2014
    Co-Authors: Ian A. Nilsen, Derek G. Osborne, Aaron M. White, Jessica M. Anna, Kevin J Kubarych
    Abstract:

    Using rapidly acquired spectral diffusion, a recently developed variation of heterodyne detected infrared photon echo spectroscopy, we observe ∼3 ps solvent independent spectral diffusion of benzene chromium tricarbonyl (C6H6Cr(CO)3, BCT) in a series of nonpolar linear alkane solvents. The spectral dynamics is attributed to low-barrier internal torsional motion. This tripod complex has two stable minima corresponding to staggered and eclipsed conformations, which differ in energy by roughly half of kBT. The solvent independence is due to the relative size of the rotor compared with the solvent molecules, which create a solvent cage in which torsional motion occurs largely free from solvent damping. Since the one-dimensional transition state is computed to be only 0.03 kBT above the higher energy eclipsed conformation, this model system offers an unusual, nearly barrierless Reaction, which nevertheless is characterized by torsional coordinate dependent vibrational frequencies. Hence, by studying the spectr...

  • Monitoring Equilibrium Reaction dynamics of a nearly barrierless molecular rotor using ultrafast vibrational echoes
    Journal of Chemical Physics, 2014
    Co-Authors: Ian A. Nilsen, Derek G. Osborne, Aaron M. White, Jessica M. Anna, Kevin J Kubarych
    Abstract:

    Using rapidly acquired spectral diffusion, a recently developed variation of heterodyne detected infrared photon echo spectroscopy, we observe ∼3 ps solvent independent spectral diffusion of benzene chromium tricarbonyl (C6H6Cr(CO)3, BCT) in a series of nonpolar linear alkane solvents. The spectral dynamics is attributed to low-barrier internal torsional motion. This tripod complex has two stable minima corresponding to staggered and eclipsed conformations, which differ in energy by roughly half of kBT. The solvent independence is due to the relative size of the rotor compared with the solvent molecules, which create a solvent cage in which torsional motion occurs largely free from solvent damping. Since the one-dimensional transition state is computed to be only 0.03 kBT above the higher energy eclipsed conformation, this model system offers an unusual, nearly barrierless Reaction, which nevertheless is characterized by torsional coordinate dependent vibrational frequencies. Hence, by studying the spectral diffusion of the tripod carbonyls, it is possible to gain insight into the fundamental dynamics of internal rotational motion, and we find some evidence for the importance of non-diffusive ballistic motion even in the room-temperature liquid environment. Using several different approaches to describe Equilibrium kinetics, as well as the influence of reactive dynamics on spectroscopic observables, we provide evidence that the low-barrier torsional motion of BCT provides an excellent test case for detailed studies of the links between chemical exchange and linear and nonlinear vibrational spectroscopy.

George J. Moridis - One of the best experts on this subject based on the ideXlab platform.

  • comparison of kinetic and Equilibrium Reaction models in simulating gas hydrate behavior in porous media
    Energy Conversion and Management, 2007
    Co-Authors: Michael B. Kowalsky, George J. Moridis
    Abstract:

    In this study we compare the use of kinetic and Equilibrium Reaction models in the simulation of gas (methane) hydrate behavior in porous media. Our objective is to evaluate through numerical simulation the importance of employing kinetic versus Equilibrium Reaction models for predicting the response of hydrate-bearing systems to external stimuli, such as changes in pressure and temperature. Specifically, we (1) analyze and compare the responses simulated using both Reaction models for natural gas production from hydrates in various settings and for the case of depressurization in a hydrate-bearing core during extraction; and (2) examine the sensitivity to factors such as initial hydrate saturation, hydrate Reaction surface area, and numerical discretization. We find that for large-scale systems undergoing thermal stimulation and depressurization, the calculated responses for both Reaction models are remarkably similar, though some differences are observed at early times. However, for modeling short-term processes, such as the rapid recovery of a hydrate-bearing core, kinetic limitations can be important, and neglecting them may lead to significant under-prediction of recoverable hydrate. Assuming validity of the most accurate kinetic Reaction model that is currently available, the use of the Equilibrium Reaction model often appears to be justified and preferred for simulating the behavior of gas hydrates, given that the computational demands for the kinetic Reaction model far exceed those for the Equilibrium Reaction model.

  • Comparison of kinetic and Equilibrium Reaction models in simulating the behavior of porous media
    Lawrence Berkeley National Laboratory, 2006
    Co-Authors: Michael B. Kowalsky, George J. Moridis
    Abstract:

    In this study we compare the use of kinetic and Equilibrium Reaction models in the simulation of gas (methane) hydrate behavior in porous media. Our objective is to evaluate through numerical simulation the importance of employing kinetic versus Equilibrium Reaction models for predicting the response of hydrate-bearing systems to external stimuli, such as changes in pressure and temperature. Specifically, we (1) analyze and compare the responses simulated using both Reaction models for natural gas production from hydrates in various settings and for the case of depressurization in a hydrate-bearing core during extraction; and (2) examine the sensitivity to factors such as initial hydrate saturation, hydrate Reaction surface area, and numerical discretization. We find that for large-scale systems undergoing thermal stimulation and depressurization, the calculated responses for both Reaction models are remarkably similar, though some differences are observed at early times. However, for modeling short-term processes, such as the rapid recovery of a hydrate-bearing core, kinetic limitations can be important, and neglecting them may lead to significant under-prediction of recoverable hydrate. Assuming validity of the most accurate kinetic Reaction model that is currently available, the use of the Equilibrium Reaction model often appears to be justified and preferred for simulating the behavior of gas hydrates, given that the computational demands for the kinetic Reaction model far exceed those for the Equilibrium Reaction model.

  • comparison of kinetic and Equilibrium Reaction models in simulating gas hydrate behavior in porous media
    Lawrence Berkeley National Laboratory, 2006
    Co-Authors: Michael B. Kowalsky, George J. Moridis
    Abstract:

    In this study we compare the use of kinetic and Equilibrium Reaction models in the simulation of gas (methane) hydrate behavior in porous media. Our objective is to evaluate through numerical simulation the importance of employing kinetic versus Equilibrium Reaction models for predicting the response of hydrate-bearing systems to external stimuli, such as changes in pressure and temperature. Specifically, we (1) analyze and compare the responses simulated using both Reaction models for natural gas production from hydrates in various settings and for the case of depressurization in a hydrate-bearing core during extraction; and (2) examine the sensitivity to factors such as initial hydrate saturation, hydrate Reaction surface area, and numerical discretization. We find that for large-scale systems undergoing thermal stimulation and depressurization, the calculated responses for both Reaction models are remarkably similar, though some differences are observed at early times. However, for modeling short-term processes, such as the rapid recovery of a hydrate-bearing core, kinetic limitations can be important, and neglecting them may lead to significant under-prediction of recoverable hydrate. The use of the Equilibrium Reaction model often appears to be justified and preferred for simulating the behavior of gas hydrates, given that the computational demands for the kinetic Reaction model far exceed those for the Equilibrium Reaction model.

  • Comparison of kinetic and Equilibrium Reaction models insimulating the behavior of porous media
    Energy Conversion and Management, 2006
    Co-Authors: Michael B. Kowalsky, George J. Moridis
    Abstract:

    In this study we compare the use of kinetic and EquilibriumReaction models in the simulation of gas (methane) hydrate behavior inporous media. Our objective is to evaluate through numerical simulationthe importance of employing kinetic versus Equilibrium Reaction modelsfor predicting the response of hydrate-bearing systems to externalstimuli, such as changes in pressure and temperature. Specifically, we(1) analyze and compare the responses simulated using both Reactionmodels for natural gas production from hydrates in various settings andfor the case of depressurization in a hydrate-bearing core duringextraction; and (2) examine the sensitivity to factors such as initialhydrate saturation, hydrate Reaction surface area, and numericaldiscretization. We find that for large-scale systems undergoing thermalstimulation and depressurization, the calculated responses for bothReaction models are remarkably similar, though some differences areobserved at early times. However, for modeling short-term processes, suchas the rapid recovery of a hydrate-bearing core, kinetic limitations canbe important, and neglecting them may lead to significantunder-prediction of recoverable hydrate. Assuming validity of the mostaccurate kinetic Reaction model that is currently available, the use ofthe Equilibrium Reaction model often appears to be justified andpreferred for simulating the behavior of gas hydrates, given that thecomputational demands for the kinetic Reaction model far exceed those forthe Equilibrium Reaction model.

  • Comparison of Kinetic and Equilibrium Reaction Models inSimulating the Behavior of Gas Hydrates in Porous Media
    2006
    Co-Authors: Michael B. Kowalsky, George J. Moridis
    Abstract:

    In this study we compare the use of kinetic and Equilibrium Reaction models in the simulation of gas (methane) hydrates in porous media. Our objective is to evaluate through numerical simulation the importance of employing kinetic versus Equilibrium Reaction models for predicting the response of hydrate-bearing systems to external stimuli, such as changes in pressure and temperature. Specifically, we (1) analyze and compare the responses simulated using both Reaction models for production in various geological settings and for the case of depressurization in a core during extraction; and (2) examine the sensitivity to factors such as initial hydrate saturation, hydrate Reaction surface area, and numerical discretization. We find that for systems undergoing thermal stimulation and depressurization, the calculated responses for both Reaction models are remarkably similar, though some differences are observed at early times. Given these observations, and since the computational demands for the kinetic Reaction model far exceed those for the Equilibrium Reaction model, the use of the Equilibrium Reaction model often appears to be justified and preferred for simulating the behavior of gas hydrates.

Aaron M. White - One of the best experts on this subject based on the ideXlab platform.

  • monitoring Equilibrium Reaction dynamics of a nearly barrierless molecular rotor using ultrafast vibrational echoes
    Journal of Chemical Physics, 2014
    Co-Authors: Ian A. Nilsen, Derek G. Osborne, Aaron M. White, Jessica M. Anna, Kevin J Kubarych
    Abstract:

    Using rapidly acquired spectral diffusion, a recently developed variation of heterodyne detected infrared photon echo spectroscopy, we observe ∼3 ps solvent independent spectral diffusion of benzene chromium tricarbonyl (C6H6Cr(CO)3, BCT) in a series of nonpolar linear alkane solvents. The spectral dynamics is attributed to low-barrier internal torsional motion. This tripod complex has two stable minima corresponding to staggered and eclipsed conformations, which differ in energy by roughly half of kBT. The solvent independence is due to the relative size of the rotor compared with the solvent molecules, which create a solvent cage in which torsional motion occurs largely free from solvent damping. Since the one-dimensional transition state is computed to be only 0.03 kBT above the higher energy eclipsed conformation, this model system offers an unusual, nearly barrierless Reaction, which nevertheless is characterized by torsional coordinate dependent vibrational frequencies. Hence, by studying the spectr...

  • Monitoring Equilibrium Reaction dynamics of a nearly barrierless molecular rotor using ultrafast vibrational echoes
    Journal of Chemical Physics, 2014
    Co-Authors: Ian A. Nilsen, Derek G. Osborne, Aaron M. White, Jessica M. Anna, Kevin J Kubarych
    Abstract:

    Using rapidly acquired spectral diffusion, a recently developed variation of heterodyne detected infrared photon echo spectroscopy, we observe ∼3 ps solvent independent spectral diffusion of benzene chromium tricarbonyl (C6H6Cr(CO)3, BCT) in a series of nonpolar linear alkane solvents. The spectral dynamics is attributed to low-barrier internal torsional motion. This tripod complex has two stable minima corresponding to staggered and eclipsed conformations, which differ in energy by roughly half of kBT. The solvent independence is due to the relative size of the rotor compared with the solvent molecules, which create a solvent cage in which torsional motion occurs largely free from solvent damping. Since the one-dimensional transition state is computed to be only 0.03 kBT above the higher energy eclipsed conformation, this model system offers an unusual, nearly barrierless Reaction, which nevertheless is characterized by torsional coordinate dependent vibrational frequencies. Hence, by studying the spectral diffusion of the tripod carbonyls, it is possible to gain insight into the fundamental dynamics of internal rotational motion, and we find some evidence for the importance of non-diffusive ballistic motion even in the room-temperature liquid environment. Using several different approaches to describe Equilibrium kinetics, as well as the influence of reactive dynamics on spectroscopic observables, we provide evidence that the low-barrier torsional motion of BCT provides an excellent test case for detailed studies of the links between chemical exchange and linear and nonlinear vibrational spectroscopy.

Jessica M. Anna - One of the best experts on this subject based on the ideXlab platform.

  • monitoring Equilibrium Reaction dynamics of a nearly barrierless molecular rotor using ultrafast vibrational echoes
    Journal of Chemical Physics, 2014
    Co-Authors: Ian A. Nilsen, Derek G. Osborne, Aaron M. White, Jessica M. Anna, Kevin J Kubarych
    Abstract:

    Using rapidly acquired spectral diffusion, a recently developed variation of heterodyne detected infrared photon echo spectroscopy, we observe ∼3 ps solvent independent spectral diffusion of benzene chromium tricarbonyl (C6H6Cr(CO)3, BCT) in a series of nonpolar linear alkane solvents. The spectral dynamics is attributed to low-barrier internal torsional motion. This tripod complex has two stable minima corresponding to staggered and eclipsed conformations, which differ in energy by roughly half of kBT. The solvent independence is due to the relative size of the rotor compared with the solvent molecules, which create a solvent cage in which torsional motion occurs largely free from solvent damping. Since the one-dimensional transition state is computed to be only 0.03 kBT above the higher energy eclipsed conformation, this model system offers an unusual, nearly barrierless Reaction, which nevertheless is characterized by torsional coordinate dependent vibrational frequencies. Hence, by studying the spectr...

  • Monitoring Equilibrium Reaction dynamics of a nearly barrierless molecular rotor using ultrafast vibrational echoes
    Journal of Chemical Physics, 2014
    Co-Authors: Ian A. Nilsen, Derek G. Osborne, Aaron M. White, Jessica M. Anna, Kevin J Kubarych
    Abstract:

    Using rapidly acquired spectral diffusion, a recently developed variation of heterodyne detected infrared photon echo spectroscopy, we observe ∼3 ps solvent independent spectral diffusion of benzene chromium tricarbonyl (C6H6Cr(CO)3, BCT) in a series of nonpolar linear alkane solvents. The spectral dynamics is attributed to low-barrier internal torsional motion. This tripod complex has two stable minima corresponding to staggered and eclipsed conformations, which differ in energy by roughly half of kBT. The solvent independence is due to the relative size of the rotor compared with the solvent molecules, which create a solvent cage in which torsional motion occurs largely free from solvent damping. Since the one-dimensional transition state is computed to be only 0.03 kBT above the higher energy eclipsed conformation, this model system offers an unusual, nearly barrierless Reaction, which nevertheless is characterized by torsional coordinate dependent vibrational frequencies. Hence, by studying the spectral diffusion of the tripod carbonyls, it is possible to gain insight into the fundamental dynamics of internal rotational motion, and we find some evidence for the importance of non-diffusive ballistic motion even in the room-temperature liquid environment. Using several different approaches to describe Equilibrium kinetics, as well as the influence of reactive dynamics on spectroscopic observables, we provide evidence that the low-barrier torsional motion of BCT provides an excellent test case for detailed studies of the links between chemical exchange and linear and nonlinear vibrational spectroscopy.