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27 results on '"Rosca, Florin"'

1. Investigations of Amplitude and Phase Excitation Profiles in Femtosecond Coherence Spectroscopy

Author

Kumar, Anand T. N., Rosca, Florin, Widom, Allan, and Champion, Paul M.

Subjects
Physics - Chemical Physics, Physics - Biological Physics, Physics - Optics
Abstract

We present an effective linear response approach to pump-probe femtosecond coherence spectroscopy in the well separated pulse limit. The treatment presented here is based on a displaced and squeezed state representation for the non-stationary states induced by an ultrashort pump laser pulse or a chemical reaction. The subsequent response of the system to a delayed probe pulse is modeled using closed form non-stationary linear response functions, valid for a multimode vibronically coupled system at arbitrary temperature. When pump-probe signals are simulated using the linear response functions, with the mean nuclear positions and momenta obtained from a rigorous moment analysis of the pump induced (doorway) state, the signals are found to be in excellent agreement with the conventional third order response approach. The key advantages offered by the moment analysis based linear response approach include a clear physical interpretation of the amplitude and phase of oscillatory pump-probe signals, a dramatic improvement in computation times, a direct connection between pump-probe signals and equilibrium absorption and dispersion lineshapes, and the ability to incorporate coherence such as those created by rapid non-radiative surface crossing. We demonstrate these aspects using numerical simulations, and also apply the present approach to the interpretation of experimental amplitude and phase measurements on reactive and non-reactive samples of the heme protein Myoglobin. The role played by inhomogeneous broadening in the observed amplitude and phase profiles is discussed in detail. We also investigate overtone signals in the context of reaction driven coherent motion., Comment: RevTex, 33 pages, 9 figures

Published
2000
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4. Temperature-dependent studies of NO recombination to heme and heme proteins

Author

Ionascu, Dan, Gruia, Flaviu, Xiong Ye, Anchi Yu, Rosca, Florin, Beck, Chris, Demidov, Andrey, Champion, Paul M., and Olson, John S.

Subjects
Heme -- Chemical properties, Hemoproteins -- Chemical properties, Nitrogen oxide -- Chemical properties, Chemistry
Abstract

The rebinding kinetics of NO to the heme iron of myoglobin (Mb) is investigated as a function of temperature. The first comprehensive measurements of the temperature-dependent NO rebinding kinetics of Mb and its distal pocket mutants are presented.

Published
2005

5. Investigations of heme protein absorption line shapes, vibrational relaxation, and resonance raman scattering on ultrafast time scales

Author

Xiong Ye, Demidov, Andrey, Rosca, Florin, Wei Wang, Kumar, Anand, Ionascu, Dan, Leyun Zhu, Barrick, Doug, Wharton, David, and Champion, Paul M.

Subjects
Myoglobin -- Properties, Hemoproteins -- Properties, Raman spectroscopy -- Usage, Chemicals, plastics and rubber industries
Abstract

The flow of photoexcitation energy in biomolecules is investigated. It is demonstrated that a dynamically evolving absorption band leads directly to a time dependent complex line shape function and REP, which must be considered along with the Bose-Einstein factor when attempting to extract a time dependent vibrational temperature from picosecond resonance raman data.

Published
2003

6. Investigations of anharmonic low-frequency oscillations in heme proteins

Author

Rosca, Florin, Kumar, Anad T. N., Ionascu, Dan, Ye, Xiong, Demidov, Andrey A., Sjodin, Theodore, Wharton, David, Barrick, Douglas, Sligar, Stephen G., Yonetani, Takashi, and Champion, Paul M.

Subjects
Chemistry, Physical and theoretical -- Research, Hemoproteins -- Physiological aspects, Oscillation -- Physiological aspects, Photochemical research -- Analysis, Absorption -- Physiological aspects, Chemicals, plastics and rubber industries
Published
2002

7. Water penetration and binding to ferric myoglobin

Author

Cao, Wenxiang, Christian, James F., Champion, Paul M., Rosca, Florin, and Sage, J. Timothy

Subjects
Myoglobin -- Physiological aspects, Hydration -- Physiological aspects, Nitric oxide -- Physiological aspects, Protein binding -- Physiological aspects, Biological sciences, Chemistry
Abstract

Results show that water enters the heme pocket of the nitric oxide bound horse heart metmyoglobin following the dissociation of nitric oxide. Data reveal that water binds to the heme iron and eventually gets displaced when nitric oxide undergoes bimolecular rebinding with histidine-64 playing a role in the process.

Published
2001

8. Femtosecond multicolor pump: probe spectroscopy of ferrous cytochrome c

Author

Wang, Wei, Demidov, Andrey A., Rosca, Florin, Sjodin, Theodore, Sheeran, Mariel, Champion, Paul M., Cao, WenXiang, and Ye, Xiong

Subjects
Cytochrome c -- Research, Cytochrome c -- Optical properties, Cytochrome c -- Chemical properties, Laser spectroscopy -- Usage, Chemistry, Physical and theoretical -- Research, Chemicals, plastics and rubber industries
Abstract

Cytochrome c (cyt c) is a member of the ubiquitous class of heme proteins, which function as reversible redox carriers in electron-transport chains. Ligand photolysis and subsequent electronic and structural relaxation, followed by ligand recombination, in ferrous cyt c is studied using ultrafast laser spectroscopy.

Published
2000

19. Investigations of Anharmonic Low-Frequency Oscillations in Heme Proteins

Author

Rosca, Florin, primary, Kumar, Anand T. N., additional, Ionascu, Dan, additional, Ye, Xiong, additional, Demidov, Andrey A., additional, Sjodin, Theodore, additional, Wharton, David, additional, Barrick, Douglas, additional, Sligar, Stephen G., additional, Yonetani, Takashi, additional, and Champion, Paul M., additional

Published
2001
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