Investigations of Photosynthetic Light Harvesting by Two-dimensional Electronic Spectroscopy PDF Download
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Author: Elizabeth Louise Read
Publisher:
ISBN:
Category :
Languages : en
Pages : 362
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Author: Elizabeth Louise Read
Publisher:
ISBN:
Category :
Languages : en
Pages : 362
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Author: Scott McClure
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Tessa Rae Calhoun
Publisher:
ISBN:
Category :
Languages : en
Pages : 140
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Two-dimensional (2D) electronic spectroscopy has recently emerged as a powerful technique for the study of complex photodynamics in a variety of condensed phase systems. The application of this technique to both photosynthetic pigment-protein complexes and chromophore solutions has provided insight into their intricate excitation energy transfer mechanisms and landscapes. Analysis of beating peak amplitudes in 2D spectra of the Fenna-Matthews-Olson bacteriochlorophyll complex combined with changing lineshapes has revealed signals consistent with excitonic coherence. In addition, the long lifetime of the coherence indicates a reversible, wavelike motion of energy through the complex as opposed to the classical hopping picture. This quantum-mechanical behavior may explain the near unity quantum efficiency of excitation energy transfer observed in networks of photosynthetic complexes. The inclusion of a noncollinear optical parametric amplifier producing broad bandwidth pulses enables the exploration of excitonic coherence in Light Harvesting Complex II, the most abundant antenna complex in higher plants. Long-lived quantum coherence is again observed suggesting this to be a universal phenomenon in natural photosynthetic systems. To expand upon these findings, a coherence power spectrum is produced. This novel technique allows the first direct experimental determination of the excitonic energy levels. In another set of experiments, the building an adaptive, pulse-shaping apparatus allows optimal compression of the broad bandwidth pulses for use in probing the debated electronic structure of [beta]-carotene. Oscillating lineshapes reveal coupling of electronic states to high energy vibrational modes while the short pulses allow the initial dynamics of this system to be studied in unprecedented detail revealing several new features whose origins are still under investigation.
Author: Eleonora De Re
Publisher:
ISBN:
Category :
Languages : en
Pages : 114
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This dissertation presents the application of ultrafast spectroscopy to the investigation of pigment-protein complexes (PPCs) involved in energy transfer and energy dissipation in photosynthetic organisms. PPCs are the building blocks of all photosynthetic organisms, and within individual pigment-protein complexes, energy transfer dynamics occur over fast timescales and broad spectral regions. Chapter 1 gives an introduction to the capability of photosynthetic organisms to absorb light energy, funnel this energy to a location for charge separation, and perform charge separation with subsequent conversion into chemical energy. All of these functions need to be performed efficiently under different light conditions. This chapter also includes a discussion of the different light harvesting strategies that various photosynthetic organisms have evolved. Lastly, this chapter discusses the application of ultrafast spectroscopy as an excellent tool to study the dynamics of PPCs. The three experimental techniques used in this dissertation are introduced in this chapter. Chapters 2 and 3 present the application of two ultrafast spectroscopic techniques, two dimensional electronic spectroscopy and transient absorption spectroscopy, to the investigation of the structure-function relationship of photosynthetic pigment-protein complexes. Chapter 2 is an investigation of the photophysics of the two forms of the Orange Carotenoid Protein, involved in excess energy dissipation in cyanobacteria. Ultrafast spectroscopy allows us to understand how a conformational change that modifies pigment-protein interactions is able to generate a different biological function. Chapter 3 presents degenerate and non-degenerate two dimensional electronic spectroscopy experiments to investigate the energy transfer dynamics and couplings in the bacterial reaction center, which is the location of charge separation. Chapter 4 investigates a PPC involved in excess energy dissipation in green algae, LhcSR. Fluorescence lifetime spectroscopy is used to investigate the excited state properties of LhcSR, which plays a role as light harvester, pH sensor and quencher in algae. The results allow us to identify two conformations, a light harvesting one and a quenching one. Transient absorption spectroscopy is used to investigate the energy transfer pathways involved in quenching in the two different conformations. Finally, Chapter 5 presents conclusions and extensions to future work, in order to improve our understanding of the energy transfer dynamics in natural photosynthetic systems.
Author: Gabriela Sadira Schlau-Cohen
Publisher:
ISBN:
Category :
Languages : en
Pages : 102
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Book Description
Experiments using two-dimensional (2D) electronic spectroscopy to investigate the structure-function relationships that give rise to photosynthetic energy transfer within pigment protein complexes are presented and discussed in this dissertation. 2D electronic spectroscopy using ultrafast laser pulses throughout the visible regime was applied to study excitation energy transfer in the major light harvesting complex of photosystem II (LHCII) and the reaction center from purple bacteria. These experiments elucidated information about the excited state structure and the energy transfer timescales within these complexes. All-parallel 2D spectroscopy was used to monitor the energy transfer dynamics in LHCII and reveals previously unobserved sub-100 fs energy transfer between the chlorophyll-b (Chl-b) and chlorophyll-a (Chl-a) bands and within the Chl-a band. Reproducing these results with simulations led to improvements in the values of the uncoupled transition energies of the chlorophyll in the working Hamiltonian of LHCII. The delocalized excited states observed in the experimental and theoretical results were found to increase the range of optimal angles for energy transfer from LHCII to neighboring pigment-protein complexes, as opposed to the case of a single, isolated donor excited state. Polarized 2D spectroscopy experiments reported here identified previously unresolved excitation energy transfer steps in LHCII. These results were used to determine the angle between transition dipole moments of the donor and acceptor. A new method was developed to use the angle between transition dipole moments to find the uncoupled transition energies of the chlorophyll, previously the major unknown for an accurate electronic Hamiltonian. This method was applied to LHCII. Quantum coherence, or a long-lived superposition of excited states, was observed in LHCII using a second polarization sequence. The observable timescales of coherence was determined to be 700-900 fs, which illustrates that quantum coherence lasts longer than many energy transfer steps. The potential contribution of coherence to the robustness of photosynthetic energy transfer to the rugged energy landscape and to temperature variations is discussed. Experiments on the B band of the bacterial reaction center were able to isolate the previously inseparable two peaks and observe energy transfer between these two excited states. A new extension of 2D spectroscopy, two-color 2D spectroscopy, was demonstrated for examining the interactions between two spectrally separate chromophores. Using this approach, energy was found to transfer from the carotenoid to the bacteriochlorophyll both via S1 and via Qx in the bacterial reaction center in an approximately 2:1 ratio, and within about 750 fs.
Author: Roberta Croce
Publisher: CRC Press
ISBN: 1351242873
Category : Science
Languages : en
Pages : 793
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Book Description
This landmark collective work introduces the physical, chemical, and biological principles underlying photosynthesis: light absorption, excitation energy transfer, and charge separation. It begins with an introduction to properties of various pigments, and the pigment proteins in plant, algae, and bacterial systems. It addresses the underlying physics of light harvesting and key spectroscopic methods, including data analysis. It discusses assembly of the natural system, its energy transfer properties, and regulatory mechanisms. It also addresses light-harvesting in artificial systems and the impact of photosynthesis on our environment. The chapter authors are amongst the field’s world recognized experts. Chapters are divided into five main parts, the first focused on pigments, their properties and biosynthesis, and the second section looking at photosynthetic proteins, including light harvesting in higher plants, algae, cyanobacteria, and green bacteria. The third part turns to energy transfer and electron transport, discussing modeling approaches, quantum aspects, photoinduced electron transfer, and redox potential modulation, followed by a section on experimental spectroscopy in light harvesting research. The concluding final section includes chapters on artificial photosynthesis, with topics such as use of cyanobacteria and algae for sustainable energy production. Robert Croce is Head of the Biophysics Group and full professor in biophysics of photosynthesis/energy at Vrije Universiteit, Amsterdam. Rienk van Grondelle is full professor at Vrije Universiteit, Amsterdam. Herbert van Amerongen is full professor of biophysics in the Department of Agrotechnology and Food Sciences at Wageningen University, where he is also director of the MicroSpectroscopy Research Facility. Ivo van Stokkum is associate professor in the Department of Physics and Astronomy, Faculty of Sciences, at Vrije Universiteit, Amsterdam.
Author: John P. Otto
Publisher:
ISBN: 9780438087927
Category :
Languages : en
Pages : 132
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Book Description
The world's energy requirements are always increasing, but sunlight provides more than sufficient energy to sustain humanity's energetic needs for decades to come. In developing future generations of light harvesting materials, scientists can turn to biology to provide design rules for efficient and robust methods of converting sunlight to address these requirements. Photosynthetic antenna complexes demonstrate remarkable efficiency and resilience, including capabilities to regulate light harvesting activity in the presence of hazards such as oxidizing agents. Through control of the environment surrounding chromophores, these complexes exercise incredible control of electronic dynamics to a level not yet achievable in manmade systems. In this dissertation I investigate biological and manmade approaches to controlling electronic dynamics via external processes on the scaffolds that hold chromophores in place. These investigations use two-dimensional electronic spectroscopy to correlate excitation energy with emission and absorption at later times as a probe of electronic couplings and dynamics on the femtosecond to nanosecond timescale. In the course of this study, I identify a potential redox protection mechanism in the Fenna-Matthews-Olson light harvesting complex arising from a structural motif repurposed from redox enzymes. Moving to synthetic light harvesting structures, I observe how nuclear motion can limit energy transfer outside the bounds predicted by Forster theory in a temperature-controlled resorcin[4]arene molecular switch. In a study of vibronically coupled cyanine dimers bound to DNA, I found evidence for multi-mode vibrational coupling that may lead to new paths for efficient energy transfer, and I propose new experiments making use of DNA nanostructures to explore this area further. Combined, these observations will lead to new designs for light harvesting materials that can help to meet future energy generation requirements.
Author: Minhaeng Cho
Publisher: Springer
ISBN: 9811397538
Category : Science
Languages : en
Pages : 404
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Book Description
This book will fulfill the needs of time-domain spectroscopists who wish to deepen their understanding of both the theoretical and experimental features of this cutting-edge spectroscopy technique. Coherent Multidimensional Spectroscopy (CMDS) is a state-of-the-art technique with applications in a variety of subjects like chemistry, molecular physics, biochemistry, biophysics, and material science. Due to dramatic advancements of ultrafast laser technologies, diverse multidimensional spectroscopic methods utilizing combinations of THz, IR, visible, UV, and X-ray radiation sources have been developed and used to study real time dynamics of small molecules in solutions, proteins and nucleic acids in condensed phases and membranes, single and multiple excitons in functional materials like semiconductors, quantum dots, and solar cells, photo-excited states in light-harvesting complexes, ions in battery electrolytes, electronic and conformational changes in charge or proton transfer systems, and excess electrons and protons in water and biological systems.
Author:
Publisher:
ISBN: 9789464231007
Category :
Languages : en
Pages : 0
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Book Description
Oxygenic photosynthesis is the fundamental process by which sunlight energy is stored as chemical energy in organic compounds and oxygen is released in the atmosphere. It starts with the capture of a photon by one of the pigments embedded within one of the two photosystems, Photosystem I (PSI) or II (PSII). These photosystems are large assemblies of many pigments held together by the protein scaffold. The absorption of the photon brings the pigment to an electronic excited state. The excitation energy is then transferred from pigment-to-pigment to the reaction center (RC) of the photosystem, where it is used to perform charge separation (CS). The pigment-to-pigment energy transfer within photosynthetic complexes occurs on a very fast, femtosecond (fs, 10^(-15) second) to picosecond (ps, 10^(-12) second) timescale, which ensures that the photosystems are extremely efficient in using the energy for charge separation. In this thesis, aspects of the light-harvesting of photosynthetic pigment-protein complexes were investigated. The spectroscopic properties (absorption, emission) and energy-transfer processes were studied with a variety of different techniques, including advanced ultrafast time-resolved spectroscopic methods (two-dimensional electronic spectroscopy (2DES) and time-resolved fluorescence spectroscopy). In these time-resolved experiments, the complexes are excited with ultrashort (fs temporal width) pulses of light, after which the optical response (photon-echo, fluorescence) is monitored in time. By measuring these signals, excitation energy transfer (EET) and energy trapping within these complexes can be determined. Oxygenic photosynthesis is mainly powered by visible light in the 400–700 nm range. Expanding the absorption range to 750 nm would result in 19% more photons available for photosynthesis [Chen, M. & Blankenship, R. E. (2011) Trends Plant Sci., 16, 427–431].
Author: Roberta Croce
Publisher: CRC Press
ISBN: 1351242881
Category : Science
Languages : en
Pages : 611
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Book Description
This landmark collective work introduces the physical, chemical, and biological principles underlying photosynthesis: light absorption, excitation energy transfer, and charge separation. It begins with an introduction to properties of various pigments, and the pigment proteins in plant, algae, and bacterial systems. It addresses the underlying physics of light harvesting and key spectroscopic methods, including data analysis. It discusses assembly of the natural system, its energy transfer properties, and regulatory mechanisms. It also addresses light-harvesting in artificial systems and the impact of photosynthesis on our environment. The chapter authors are amongst the field’s world recognized experts. Chapters are divided into five main parts, the first focused on pigments, their properties and biosynthesis, and the second section looking at photosynthetic proteins, including light harvesting in higher plants, algae, cyanobacteria, and green bacteria. The third part turns to energy transfer and electron transport, discussing modeling approaches, quantum aspects, photoinduced electron transfer, and redox potential modulation, followed by a section on experimental spectroscopy in light harvesting research. The concluding final section includes chapters on artificial photosynthesis, with topics such as use of cyanobacteria and algae for sustainable energy production. Robert Croce is Head of the Biophysics Group and full professor in biophysics of photosynthesis/energy at Vrije Universiteit, Amsterdam. Rienk van Grondelle is full professor at Vrije Universiteit, Amsterdam. Herbert van Amerongen is full professor of biophysics in the Department of Agrotechnology and Food Sciences at Wageningen University, where he is also director of the MicroSpectroscopy Research Facility. Ivo van Stokkum is associate professor in the Department of Physics and Astronomy, Faculty of Sciences, at Vrije Universiteit, Amsterdam.
