Doctor of Philosophy / Department of Chemistry / Ryszard J. Jankowiak / This dissertation reports the low temperature frequency domain spectroscopic study of three different natural pigment protein complexes and one artificial antenna system. The main focus of this work is to better understand electronic structure, excitation energy transfer (EET), and electron transfer (ET) dynamics in these systems that could have impact on achieving higher efficiency in future artificial solar cells. In the first part of this dissertation, electronic structure and EET pathways in isolated intact CP43 prime protein complex, which is isolated from Cyanobacterium synechocystis PCC 6803 grown under iron stressed conditions, are investigated using low-temperature absorption, fluorescence, fluorescence excitation, and hole-burning (HB) spectroscopies. This work suggests that, in analogy to the CP43 complex of PSII core, CP43 prime possesses two quasi-degenerate low energy states, A prime and B prime. The various low-temperature optical spectra are fitted considering an uncorrelated EET model. This work suggests that for optimal energy transfer from CP43 prime to PSI, the A prime and B prime state chlorophylls belonging to each CP43 prime should face towards the PSI core. The second part of dissertation reports the photochemical HB study on novel Zinc bacterial reaction center (Zn-RC) from Rhodobacter sphaeroides and its β-mutant (Zn-β-RC). This study shows that ET in the two samples is similar; however, the quantum efficiency of charge separation in the mutant decreases by 60 %. This finding suggests that the coordination state of the HA site zinc bacteriochlorophyll does not tune the active branch ET. Simultaneous fits of various optical spectra using experimentally determined inhomogeneity provides more reliable electron phonon coupling parameters for the P870 state of both RC samples. In the last part of this dissertation, EET in a novel artificial antenna system (ethynyl linked chlorophyll trefoil, ChlT1) is investigated. EET time in ChlT1 is ~2 ps. ChlT1 in MTHF/ethanol glass forms four different types of aggregates, A1-A4. The EET time in A1 and A2 type aggregates slows down only by a factor of 5 and 7, respectively. This study suggests that ChlT1 and its aggregates can be used as efficient antenna systems in designing organic solar cells.

Thesis (Ph. D.)--Montana State University--Bozeman, 2003. / Typescript. Chairperson, Graduate Committee: Aleksander Rebane. Includes bibliographical references (p. 178-199).

Harvesting only 4 % of light striking the Earth could possibly fulfill present energy demands of a mankind. Chlorosome of green sulfur bacteria is re- garded as suitable light-harvesting system for photosynthesis imitation. This work presents comparison of absorption and hole burning spectra of artificially prepared aggregates similar to chlorosomes with different compositions in order to verify the proposed role of quinones in excitation quenching and its redox de- pendence. Absorption spectra at room and helium temperature showed a resem- blance between artificial aggregates and chlorosomes. Hole burning experiments verified the role of quinones in excitation quenching under aerobic conditions. Even more pronounced excitation quenching was observed under anaerobic con- ditions. Significant improvements of the original experimental set-up provided better experimental data which raised many further question that are worth trying to answer in the future.

Doctor of Philosophy / Chemistry / Ryszard J. Jankowiak / The structure-function relationships of natural pigment–protein complexes are of great interest, as the electronic properties of the pigments are tuned by the protein environment to achieve high quantum yields and photon utilization. Determination of electronic structure and exciton dynamics in protein complexes is complicated by static disorder and uncertainties in the properties of system-bath coupling. The latter is described by the phonon profile (or spectral density), whose shape can only be reliably measured experimentally for the lowest energy state. Low-temperature, laser-based spectroscopies are applied towards model pigment–protein complexes, i.e., the Fenna-Matthews-Olson (FMO) and water-soluble chlorophyll-binding (WSCP) complexes, in order to study system-bath coupling and energy transfer pathways. Site-selective techniques, e.g., hole burning (HB) and fluorescence line narrowing, are utilized to overcome static disorder and reveal details on homogeneous broadening. In addition, excitonic calculations with non-Markovian lineshapes provide information on electronic structure and exciton dynamics. A new lognormal functional form of the spectral density is recommended which appropriately defines electron-phonon parameters, i.e., Huang-Rhys factor and reorganization energy. Absorbance and fluorescence spectral shifts and HB spectra reveal that samples of FMO may contain a subpopulation of destabilized proteins with modified HB efficiencies. Simulations of spectra corresponding to intact proteins indicate that the entire trimer has to be taken into account in order to properly describe fluorescence and HB spectra. The redshifted fluorescence spectrum of WSCP is described by uncorrelated energy transfer as opposed to previous models of excited state protein relaxation. Also, based on nonconservative HB spectra measured for WSCP, a mechanism of electron transfer between chlorophylls and aromatic amino acids is proposed.

Dans de nombreux systèmes de traitement de l'information, le signal est numérisé, traité informatiquement, puis reconverti dans le domaine analogique. La faible bande passante de ces étapes de conversion numérique/analogique limite considérablement le débit d'informations traitées. Une solution purement analogique améliorerait donc considérablement le temps de traitement et la bande passante. Notre approche consiste à transférer le signal RF à traiter sur une porteuse optique puis à procéder à son traitement dans le domaine optique. L'étape de traitement est assurée par la traversée d'un cristal dopé en ions terres rares convenablement "programmé". Cette étape de programmation consiste à graver dans le profil d'absorption du cristal une fonction caractéristique de l'opération de traitement du signal à réaliser. Deux opérations ont ainsi été implémentées : 1) le renversement temporel de signaux RF : c'est l'opération consistant à générer analogiquement le signal renversé temporellement s(−t) d'un signal incident s(t). La fonction à graver dans le profil d'un cristal d'Er:YSO est alors un réseau spectral de pas variable. 2) l'analyse spectrale large bande instantanée : c'est l'opération permettant d'accéder au contenu spectral d'un signal. On impose au protocole de fournir instantanément le spectre d'un signal large bande. La fonction à graver dans le profil d'un cristal de Tm:YAG est alors un réseau spectro-spatial de pas variable. / Many signal processing devices rely on the digitalization of the incoming signal. After being processed by a computer, the signal needs to be converted back to its original analog form. Due to the limited bandwidth of analog-to-digital and digital-to-analog stages, the data flow rate is significantly limited. A purely analog solution would then significantly improve the processing time and bandwidth. In our approach, we first transfer the incoming RF signal on an optical carrier, allowing us to process it in the optical domain. For the processing stage, we propose to engrave the absorption profile of a rare earth ion-doped crystal with different shapes (each shape is specific to one processing operation). In this work, two operations are implemented: 1) time reversal of RF signals: we analogically generate the time reversed replica s(−t) of an incoming signal s(t). For this purpose, the shape to be engraved in the absorption profile of a Er:YSO crystal is a non-periodic spectral grating. 2) instantanous broadband spectral analysis: we want to instantaneously access the spectral components of a broadband signal. For this purpose, the shape to be engraved in the absorption profile of a Tm:YAG crystal is a spectro-spatial grating with a variable period.

Doctor of Philosophy / Department of Chemistry / Ryszard J. Jankowiak / The constituents of oxygen-evolving photosystem II core complexes—antenna proteins (CP43 and CP47) and reaction center (RC)—have been the subject of many studies over the years. However, the various issues related to electronic structure, including the origin/composition of the lowest-energy traps, origin of various emission bands, excitation energy transfer (EET), primary charge separation (CS) processes and pigment site energies remain yet to be fully resolved. Exploiting our state-of-the-art techniques such as low-T absorption, fluorescence, and hole burning (HB) spectroscopies, we resolved some of the issues particularly related to CP47 and isolated RC protein complexes. For example, we demonstrated that the fluorescence origin band maximum (~695 nm) originates from the lowest-energy state ~693 nm of intact CP47. In intact CP47 in contrast to destablished protein complexes, the band (~695 nm) does not shift in the temperature range of 5–77 K unless hole-burning takes place. We also studied a large number of isolated RC preparations from spinach, and wild-type Chlamydomonas reinhardtii (at different levels of intactness), as well as its mutant (D2-L209H), in which the active branch pheophytin (PheoD1) has been genetically replaced with chlorophyll a (Chl a). We showed that the Qx-/Qy-region site-energies of PheoD1 and PheoD2 are ~545/680 nm and ~541.5/670 nm, respectively, in good agreement with our previous assignment [Jankowiak et al. J. Phys. Chem. B 2002, 106, 8803]. Finally, we demonstrated that the primary electron donor in isolated algal RCs from C. reinhardtii (referred to as RC684) is PD1 and/or PD2 of the special Chl pair (analogous to PL and PM, the special BChl pair of the bacterial RC) and not ChlD1. However, the latter can also be the primary electron donor (minor pathway) in RC684 depending on the realization of the energetic disorder. We further demonstrate that transient HB spectra in RC684 are very similar to P+QA - PQA spectra measured in PSII core, providing the first evidence that RC684 represent intact isolated RC that also possesses the secondary electron acceptor, QA. In summary, a new insight into possible charge separation pathways in isolated PSII RCs has been provided.

Semiconductor ring laser diodes (SLD) have been receiving attention for their potential use as source in photonic integrated circuits. Advantages of a ring laser include ease of integration because of no need for cleaved facets and they can be made very compact by folding their cavity . Ring laser have a unique feature, clockwise and counter- clockwise, in their lasing modes. If unidirectional traveling-wave oscillation can be achieved, spatial hole burning effects seen in Fabry-Perot and distributed feedback lasers can be avoided. In this work, the unidirectional oscillation is accomplished by controlling the taper shape structure. The whole laser cavity is formed using four reflection mirrors (TIR) and an output coupler passive waveguide. According to the Beam propagation Method (BPM) simulation, we find that the clockwise and counterclockwise oscillations have different behavior under various taper shape , indicating bidirectional oscillation can be eliminated. Moreover, bending loss¡Bmode transformation and optical gain are all included in calculation model. The waveguide is fabricated in the following steps: (1) ion implantation to get electrical isolation (2) selectively wet etching to form waveguide ridge (3) evaporation n- and p- electrode (4)spatter with Si3N4(5) planarization (6) evaporation microwave transmission line.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18283号 / 工博第3875号 / 新制||工||1594(附属図書館) / 31141 / 京都大学大学院工学研究科電子工学専攻 / (主査)教授 野田 進, 教授 川上 養一, 教授 藤田 静雄 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Hole-Burning (HB) und Fluorescence Line-Narrowing (FLN) bei 4.2 K sowie Experimente zur Temperaturabhängigkeit werden angewendet, um Energieniveaustruktur und Elektron-Phonon- Wechselwirkung im Antennenkomplex LHC II grüner Pflanzen zu untersuchen. Besondere Aufmerksamkeit gilt dabei der Vermeidung systematischer Meßfehler durch Reabsorption von Fluoreszenz oder durch Lichtstreuung und unerwünschtes Lochbrennen bei FLN-Experimenten. Durch die Auswertung von Lochspektren können erstmals drei niederenergetische elektronische Zustände bei 677.1, 678.4 und 679.8 nm nachgewiesen werden. Die inhomogene Breite der zugehörigen Absorptionsbanden beträgt etwa 4 nm. Wahrscheinlich stellt jeder dieser Zustände das tiefste Energieniveau einer Untereinheit des LHC II-Trimers dar und ist weitgehend an jeweils einem Chl a-Molekül lokalisiert. Die energetische Differenz zwischen den drei Zuständen kann durch strukturelle Heterogenität erklärt werden. Es kann nachgewiesen werden, daß die Meßergebnisse praktisch frei von Effekten durch unerwünschte Aggregation sind. Die homogene Linienbreite des energetisch tiefsten Zustandes bei 4.7 K wird vorwiegend durch phasenzerstörende Prozesse (pure dephasing) bestimmt. Die Lochbreiten innerhalb der 650 nm Absorptionsbande entsprechen Chl b-Chl a Energietransferzeiten von 1 ps und etwa 240 fs bei 4.2 K, während Lochbreiten innerhalb der 676 nm Absorptionsbande Chl a-Chl a Energietransferzeiten in der Größenordnung von 6-10 ps ergeben. In einer theoretischen Betrachtung werden die Beiträge zu Phonon-Seitenbanden bei HB und FLN separat analysiert. Auf dieser Grundlage können Ergebnisse von HB und FLN Experimenten an LHC II erstmals in einem konsistenten Modell durch schwache Elektron-Phonon-Wechselwirkung mit einem Huang-Rhys-Faktor von 0.9 und ein breites, stark asymmetrisches Ein-Phonon-Profil erklärt werden. / Spectral hole-burning (HB) is combined with fluorescence line-narrowing (FLN) experiments at 4.2 K and studies of temperature-dependent fluorescence spectra in order to investigate low-energy level structure as well as electron-phonon coupling of the LHC II antenna complex of green plants. Special attention has been paid to eliminate effects owing to reabsorption of fluorescence and to assure that the FLN spectra are virtually unaffected by hole-burning or scattering artifacts. For the first time, analysis of the 4.2 K hole spectra reveals three low-energy electronic states at 677.1, 678.4 and 679.8 nm, respectively. The inhomogeneous width of their absorption bands is approximately 4 nm. It is likely that each of these states is associated with the lowest energy state of one trimer subunit with the energetic separations being due to structural heterogeneity. It is likely that each of the low-energy states is highly localized on a single Chl a molecule of the corresponding trimer subunit. The results are shown to be virtually free from aggregation effects. The homogeneous width for the lowest state at 4.7 K is predominantly due to pure dephasing. Widths of holes burned into the 650 nm absorption band correspond to Chl b-Chl a energy transfer times of 1 ps and about 240 fs at 4.2 K while holewidths for the 676 nm absorption band lead to Chl a-Chl a energy transfer times in the 6-10 ps range. The complexities associated with the interpretation of the phonon structure in HB and FLN spectra are discussed by theoretically analyzing the different phonon sideband contributions. On this basis, 4.2 K HB and FLN data can be consistently interpreted for the first time by weak electron-phonon coupling with a Huang-Rhys factor of about 0.9 to protein phonons with a broad and strongly asymmetric one- phonon profile.

Abstract Single frequency laser has the advantages of high stability in frequency and low noise. Therefore, single frequency laser is now widely used in applications, such as high precision measurement, holography and data storage. Attempts to generate second harmonic radiation using a linear cavity have typically resulted in significant amplitude fluctuations due to longitudinal mode coupling. Various techniques have been proposed for solving the so called ¡§green problem¡¨ to achieve single longitudinal mode operation, such as inserting optical component in the conventional linear cavity or use ring cavity instead of linear cavity. Uni-directional ring cavity has shown to be the most robust method for producing single frequency laser. The purpose of this study is to develop compact and low-cost single frequency IR and green lasers. A novel symmetrical two-mirror figure ¡§8¡¨ ring cavity is developed. Instead of using several laser mirrors for beam deflection, this ring laser system employs only two spherical mirrors to form the laser cavity for traveling wave oscillation and eliminates ¡§spatial hole burning¡¨ caused by the standing wave operation. In this thesis, we use two-mirror figure ¡§8¡¨ ring cavity for the generation of single frequency IR and green lasers. The polarization status is crucial for high efficient intracavity frequency doubling. The polarization evaluation in a nonplanar and reentrant ring cavity is characterized by measuring the thermally induced linear and circular birefringence and analyzing the polarization rotation due to cavity configuration. We have demonstrated a 2-mirror figure ¡§8¡¨ ring cavity which is compact and has few optical elements. The stable single frequency laser output of our ring cavity promises to make the design widely applicable to solid-state lasers.