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This dissertation explores the multifaceted roles of rare-earth doped hydroxyapatite in biomedical applications, bridging the gap between luminescence studies and osteogenic potential in the context of bone tissue engineering and regenerative medicine. In the second chapter, we look into the luminescence properties of terbium, cerium, and europium doped hydroxyapatite scaffolds when immersed in simulated body fluid (SBF) over a four-week period. Our comprehensive study reveals a consistent decrease in luminescence emission intensity across all samples, accompanied by a reduction in the concentration of rare-earth ions within the scaffolds, as confirmed by energy dispersive spectroscopy. Furthermore, fluorescence spectroscopy demonstrates the translocation of these ions into the SBF, indicating the scaffolds' partial dissolution over time. The employment of rare-earth ions as luminescence markers offers profound insights into apatite formation mechanisms, presenting significant implications for the development of safer and more durable materials in biomedical applications.Expanding upon the foundational knowledge established in the first and second chapters, the third chapter investigates the osteogenic potential of rare-earth doped hydroxyapatite scaffolds using a murine pre-osteoblastic cell line. This study assesses the effects of ytterbium, terbium, cerium, and europium doping on osteoblast differentiation, gauged by alkaline phosphatase activity and the expression of osteogenic marker genes such as Runx2, OCN, ALP, OPN, and BMP2. Our findings indicate a notable enhancement in differentiation activity with the incorporation of rare-earth elements, with europium and ytterbium doped HAp showing superior performance. Cathodoluminescence spectroscopy further corroborates these results by revealing distinct emission peaks specific to the Eu2+/Eu3+ and Yb2+ ions, underscoring the role of valence state incorporation in augmenting osteoblast differentiation.Collectively, this dissertation contributes expanding the field of biomaterials by elucidating the dual utility of rare-earth doped hydroxyapatite scaffolds in promoting osteogenic differentiation and providing luminescence-based insights into scaffold behavior in physiological environments. By combining the luminescence stability studies with the exploration of osteogenic potential, our research underscores the importance of integrating multifunctional elements into scaffold design to enhance their performance in bone tissue engineering. The insights garnered from both studies not only pave the way for the development of novel biomaterials but also highlight the potential of rare-earth elements as pivotal components in the advancement of regenerative medicine and biomedical engineering.

346 p. (eng.) 246 p. (eusk.) En esta tesis se desarrollan y estudian materiales híbridos zeotípicos fotoactivos para la obtención de sistemas multifuncionales en estado sólido con interesantes propiedades ópticas aptas para aplicaciones en el campo de la fotónica. Para ello, se atrapan colorantes orgánicos en nanocavidades restringidas de estructuras inorgánicas de aluminofosfato dopadas con metales (con Si o Mg, obteniendo estructuras tipo SAPO y MgAPO, respectivamente) para promover procesos fotofísicos nuevos y/o mejorados en los materiales por efecto sinérgico, en comparación con los fluoróforos aislados.En este trabajo se preparan un gran número de materiales de colorante-AlPO, combinando varias estructuras con diferentes formas y tamaños de poros/canales en el rango de dimensiones moleculares, con una amplia gama de colorantes orgánicos, principalmente de las familias de estirilos y aromáticos fusionados de tres anillos. La inclusión de fluoróforos en las cavidades de los AlPOs realizada "in situ" por el método de inclusión por cristalización permite el desarrollo directo de materiales híbridos fluorescentes con funcionalidades ópticas destacadas y específicas en un solo paso y en cortos periodos de tiempo, describiendo así una síntesis rentable y eficiente para sistemas avanzados.Por un lado, como resultado de la sinergia entre moléculas fotoactivas push-pull con anfitriones de aluminofosfato canalizados en 1D (AFI, ATS y AEL) y una estructura de tipo jaula-3D (CHA), se obtienen sistemas sólidos ópticamente densos con capacidad de fluorescencia mejorada y respuesta altamente anisotrópica a la luz linealmente polarizada. A través de esta estrategia las aplicaciones logradas son diversas, desde emisores NIR hasta generadores de segundo armónico y láseres en estado sólido a nivel de partícula.Por otro lado, la oclusión simultánea de diferentes especies fotoactivas en los aluminofosfatos (IFO y AEL) promueve la probabilidad de procesos de FRET en cascada entre moléculas orgánicas ocluidas en el espacio restringido de los canales zeotípicos. La coencapsulación de especies adecuadas y racionalmente seleccionadas (pares FRET) proporciones idóneas conduce a nuevos sistemas de antenas artificiales, con propiedades como la emisión sintonizable y la emisión de luz blanca.A lo largo de este trabajo, las síntesis de los materiales híbridos dopados con colorantes se optimizan (variando la composición del gel, la temperatura y el tiempo y método de calentamiento) y la morfología y cristalización de todas las fases presentadas se comprueban mediante técnicas de SEM y difracción de rayos-X en polvo. Las propiedades fotofísicas de los materiales híbridos y de los colorantes fotoactivos se analizan en profundidad mediante técnicas de estado estacionario y resueltas en el tiempo (espectroscopias de absorción y emisión), así como mediante microscopía de fluorescencia, que permite el análisis a nivel de partícula. Además, se demuestra la aplicabilidad final de los materiales mediante técnicas sofisticadas como la detección de señales de generación de segundos armónicos y la respuesta de acción del microláser

beta-Si6-zAlzOzN8-z is a prominent example of systems suitable as hosts for creating materials for light-emitting diodes (LEDs). In this work, the electronic structure of a series of semiordered and disordered beta-Si6-zAlzOzN8-z systems is investigated by means of ab initio calculations, using the FLAPW and Green function KKR methods. Finite temperature effects are included by averaging over thermodynamic configurations within the alloy analogy model. We found that the dependence of the electronic structure on the (Al,O) concentration z is similar for semiordered and disordered structures. The electronic band gap decreases with increasing z by about 1.5 eV when going from z=0 to z=2. States at the top of the valence band are mostly associated with N atoms whereas the states at the bottom of the conduction band are mostly derived from O atoms. Increasing the temperature leads to a shift of the bottom of the conduction band to lower energies. The amount of this shift increases with increasing z.

Down conversion (DC) in rare-earth-doped optical materials is a process of great interest for the possibility of a substantial increase of the efficiency of silicon solar cells. Here we report the structural and photoluminescence properties of co-doped CaF2 phosphors obtained by hydrothermal synthesis. In particular, the DC photoluminescence characteristics for UV (353 nm) excitation of Nd3+/Yb3+ co-doped CaF2 phosphors are discussed, underlining the effects due to the co-doping with Li+. The photoluminescence emission is dominated by the near-infrared (NIR) Yb3+ emission peaked at 975 nm, although the excitation spectrum corresponds to the characteristic peaks associated with Nd3+ excitation at both the UV and visible wavelength ranges. The Nd3+ to Yb3+ energy transfer mechanisms were determined from a detailed analysis of the excitation spectra characteristics of Nd3+ and Nd3+/Yb3+/Li + doped CaF2 phosphors. DC photoluminescence for UV excitation was confirmed by both the analysis of DC quantum yield efficiency and effective quantum yield measurements. In the first case, an efficiency up to 150% was found, while the effective quantum yield measurements, carried out for the UV (DC) and visible (downshift) excitation and NIR photoluminescence emission, give values of 81 ± 10% and 37 ± 5% for excitation with 353 nm and 577 nm light, respectively.

Title: Development of novel photoactive cationic zirconocene complexes Author: Bc. David Dunlop Department: Department of inorganic chemistry Supervisor: RNDr. Martin Lamač Ph.D. Advisor: prof. RNDr. Petr Štěpnička, Ph.D., DSc. Abstract: Environmental concerns have brought about an unprecedented demand for sustainable energy sources among which electromagnetic radiation, light, currently dominates. Development of novel light- harvesting compounds and materials is at the forefront of current science, as it is essential to further our technological progress. This thesis contributes to the field by development of novel photoactive cationic group 4 metallocene complexes stabilized by pendant imine and pyridinyl donor groups, or N,O-donor aromatic ligands, as crystalline [B(C6F5)4]− salts. The complexes are prepared either by protonation of the intramolecularly bound imine moiety by PhNMe2H[B(C6F5)4] or by chloride ligand abstraction, by Li[B(C6F5)4]·2.5Et2O or in situ generated Et3Si[B(C6F5)4]. Prepared compounds were characterized by NMR spectroscopy. Solid state structures of the compounds were determined by X-ray diffraction analysis. The cationic complexes of Zr and Hf exhibited significantly enhanced luminescence which originates from triplet ligand-to-metal (3 LMCT) excited states with lifetimes of up to...

The reaction of the gold polymers containing bipyridyl and terpyridyl units, [Au(C≡CC15H10N3)]n and [Au(C≡CC10H7N2)]n, with the water-soluble phosphines 1,3,5-triaza-7-phosphatricyclo[3.3.1.13.7]decane and 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane gives rise to the formation of four gold(I) alkynyl complexes that self-assemble in water (H2O) and dimethyl sulfoxide (DMSO), through different intermolecular interactions, with an impact on the observed luminescence displayed by the supramolecular assemblies. A detailed analysis carried out by NMR studies performed in different DMSO/deuterated H2O mixtures indicates the presence of two different assembly modes in the aggregates: (i) chain assemblies, which are based mainly on aurophilic interactions, and (ii) stacked assemblies, which are based on Au···π and π···π interactions. These different supramolecular environments can also be detected by their intrinsic optical properties (differences in absorption and emission spectra) and are predicted by the changes in the relative binding energy from density functional theory calculations carried out in DMSO and H2O. Small-angle X-ray scattering (SAXS) experiments performed in the same mixture of solvents are in agreement with the formation of aggregates in all cases. The aromatic units chosen, bipyridine and terpyridine, allow the use of external stimuli to reversibly change the aggregation state of the supramolecular assemblies. Interaction with the Zn2+ cation is observed to disassemble the aggregates, while encapsulating agents competing for Zn2+ complexation revert the process to the aggregation stage, as verified by SAXS and NMR. The adaptive nature of the supramolecular assemblies to the metal-ion content is accompanied by significant changes in the absorption and emission spectra, signaling the aggregation state and also the content on Zn2+. © 2017 American Chemical Society., The authors are grateful to the Ministry of Economy, Industry and Competitiveness of Spain (AEI/FEDER, UE Projects CTQ2016-76120-P, CTQ2015-65040-P, and CTQ2015-70117-R). This work was also supported by the Associated Laboratory for Sustainable Chemistry, Clean Processes and Technologies, LAQV, which is financed by national funds from FCT/MEC (UID/QUI/50006/2013) and cofinanced by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007265). The IQAC NMR Facility 500 MHz spectrometer and cryoprobe were funded by the CSIC13-4E-2076 MINECO-FEDER grant. SAXS experiments were performed at the NCD-BL11 beamline of the ALBA Synchrotron Light Facility in collaboration with the ALBA staff. A.J.M. thanks the FCT for a postdoctoral grant (SFRH/ BPD/69210/2010). This research was supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme (to R.G.). We also thank L. Gimeńez and I. Brea for their help on the synthesis of the ligands.

Title: Theoretical study of spin-orbit coupling on spectra and photophysics of rhenium complexes Author: RNDr. Radka Heydová Department: Physical and Macromolecular Chemistry Supervisor: Ing. Stanislav Záliš, CSc., JHI AS CR, v.v.i. Supervisor's e-mail address: stanislav.zalis@jh.inst-cas.cz Abstract: Relativistic effects, especially spin-orbit coupling (SOC), play an essential role in transition metal chemistry and SOC treatment is indispensable for a correct theoretical description. To demonstrate the importance of SOC, the energies and oscillator strengths of vertical transitions for a series of [ReX(CO)3(2,2'-bipyridine)] (X = Cl, Br, I) and [Re(imidazole)(CO)3(1,10-phenanthroline)]+ complexes were calculated in the spin-free (SF) and spin-orbit (SO) conceptual frameworks. Two different computational approaches were adopted: SO-MS-CASPT2 where SOC was added a posteriori using a configuration interaction model (SO-RASSI), and the approximate perturbative SO-TD-DFT method. Relativistic effects were included via the two-component Douglas-Kroll-Hess transformation and the zeroth-order regular approximation in the former and the latter technique, respectively. The SF (i.e. accounting only for the scalar relativistic effects) and SO results from both methods were compared with each other and to available...

Title: Copper(I) complexes with phosphinonitrile donors Author: Bc. Filip Horký Department: Department of Inorganic chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Abstract: Although coordination compounds with phosphinonitrile ligands are already well known, in the vast majority of these complexes these ligands coordinate as simple P-donors with their cyano groups acting as auxiliary substituents. This led us to synthesize and study a series of Cu(I) complexes with two isomeric phosphinonitrile donors, namely 2-(diphenylphosphino)benzonitrile (Lo ) and 2-(diphenylphosphino)benzonitrile (Lp ), with different ligand-to-metal ratios and possibly characterize further coordination modes offered by these hybrid donors. This work describes the preparation of phosphinonitrile complexes from the aforementioned ligands and simple copper(I) halides (CuX, X = Cl, Br, I), pseudohalides (X = CN) and from [Cu(MeCN)4][BF4]. The products were characterized by nuclear magnetic resonance, infrared spectroscopy and elemental analysis, mass spectrometry, and their solid-state structures were determined by single-crystal X-ray crystallography. In addition, luminescent properties of the Cu(I) complexes were studied and catalytic activity of selected complexes was tested in copper-catalyzed alkyne-azide cycloaddition...

Most commercially available optical oxygen sensors target the measuring range of 300 to 2 mu mol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized "sensing chemistry" that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded in a Hyflon AD 60 polymer matrix and has a K-SV of 6.25 x 10(-3) ppmv(-1). The applicable measurement range is from 1000 nM down to a detection limit of 0.5 nM. A second sensor material based on the platinum(II) analogue of the porphyrin is spectrally compatible with the readout device and has a measurement range of 20 mu M down to 10 nM. The LUMOS device is a dedicated system optimized for a high signal to noise ratio, but in principle any phase flourimeter can be adapted to act as a readout device for the highly sensitive and robust sensing chemistry. Vise versa, the LUMOS fluorimeter can be used for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used to measure nanomolar oxygen concentrations. Oxygen contamination in common sample containers has been investigated and microbial or enzymatic oxygen consumption at nanomolar concentrations is presented. Most commercially available optical oxygen sensors target the measuring range of 300 to 2 μmol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized “sensing chemistry” that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded in a Hyflon AD 60 polymer matrix and has a KSV of 6.25 x 10-3 ppmv-1. The applicable measurement range is from 1000 nM down to a detection limit of 0.5 nM. A second sensor material based on the platinum(II) analogue of the porphyrin is spectrally compatible with the readout device and has a measurement range of 20 μM down to 10 nM. The LUMOS device is a dedicated system optimized for a high signal to noise ratio, but in principle any phase flourimeter can be adapted to act as a readout device for the highly sensitive and robust sensing chemistry. Vise versa, the LUMOS fluorimeter can be used for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used to measure nanomolar oxygen concentrations. Oxygen contamination in common sample containers has been investigated and microbial or enzymatic oxygen consumption at nanomolar concentrations is presented.

Reactions in aqueous solution under hydrothermal conditions between (±)-2,3-dimethylsuccinic acid and lanthanide chlorides lead to two different isostructural types with chemical formulas [Ln2(C6H8O4)3(H2O)2] Ln(III) = Pr−Eu (except Pm) (Type I, compounds 1−4) and [Ln2(C6H8O4)3] Ln(III) = Tb−Yb (except Tm) (Type II, compounds 5−9). The crystal structure has been solved for the Pr (1)-, Sm (3)-, and Ho (7)-containing compounds by means of single-crystal XRD methods, whereas powder XRD Rietveld refinement was used for the rest of the MOFs. Compounds 1−4 crystallize in the triclinic space group P1̅, whereas compounds 5−9 belong to the tetragonal space group P43212. Type I and II compounds are 3D frameworks consisting of chains of [LnO8(H2O)] or [LnO8] polyhedra, respectively, linked by dimethylsuccinate anions, giving rise to I1 O2 connectivity. All the compounds were characterized by X-ray diffraction, variable-temperature Fourier transform infrared spectroscopy, and thermal analysis. An exhaustive topological study was performed in comparison with other related compounds. The photoluminescent (PL) properties for compounds 3, 4, and 5 have been also explored, indicating that a metal-centered luminescent process takes place. Fil: Gomez, Germán Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; Argentina; Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Area Química General e Inorgánica; Argentina; Fil: Bernini, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina; Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Area Química General e Inorgánica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; Argentina; Fil: Brusau, Elena Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; Argentina; Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Area Química General e Inorgánica; Argentina; Fil: Narda, Griselda Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; Argentina; Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Area Química General e Inorgánica; Argentina; Fil: Massad, Walter Alfredo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina; Fil: Labrador, Ana. Lund University. MAX IV Laboratory; Suecia

Title: Bioapplications of novel nanostructured materials Author: Anna Fučíková Department / Institute: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Supervisor of the doctoral thesis: Doc. RNDr. Jan Valenta, Ph.D., Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This work is aimed at development of new fluorescent labels based on silicon nanocrystals. Nanodiamonds and commercial CdSe quantum dots have been used as comparative materials. Silicon nanocrystals are relatively small (1-4 nm) compared to other studied nanomaterials. They are prepared by electro-chemical etching and their surface can be activated by various molecules which strongly influences luminescence properties. Luminescence quantum efficiency can be as high as 30 % and perfectly photostable even in biological environment. Si nanocrystals are biodegradable in a living organism within reasonable time scale and non-toxic. We are able to detect luminescence of single nanocrystals, even inside living cells, with use of our micro-spectroscopy apparatus. Nanodiamonds have weak luminescence; they are toxic at higher dosages and very stable in living bodies (without available technique how to remove them). Studied CdSe...

L’artiste moderne cherche continuellement de nouvelles techniques. Des nouveaux matériaux tels que l’éponge, le polyester, le sable, etc. sont devenus courants. Ces développements amènent de nouveaux problèmes dans le domaine de la conservation (préventive) des matériaux en question. Chaque matériau doit être analysé individuellement afin de préserver le mieux possible l’intention de l’artiste à long terme. La présente recherche concerne des matériaux très récents: les pigments et les couleurs fluorescentes. Ces derniers n’ont fait leur apparition qu’au vingtième siècle. Pour cette raison les données concernant leur dégradation et leur conservation sont peu nombreuses. La majorité des tableaux fluorescents sont conçus pour être montrés sous éclairage UV. En cas de dommage, si l’œuvre a besoin d’être retouchée, ceci pose un grand problème esthétique. La retouche devient visible sous les lampes UV. La première partie de la recherche concerne la composition des différentes sortes de pigments et de peintures. Par la suite, les différentes causes de dégradation- lumière UV, chaleur, etc.- sont analysées en détail. Pour conclure, un possible remède est proposé.In modern art we can see that artists are breaking with traditional techniques. New materials like sponge, polyester, sand, etc. are being used. This causes a lot of new problems in the (preventive) conservation of works containing these materials. Every material needs to be researched individually so the exact intention of the artist can be preserved for a (relatively) long period. My research is about very recent materials: fluorescent pigments and paints. These only started to be used by artists from the 60’s. That's why there is not much information about their aging and ways to (preventively) conserve them. A lot of fluorescent paintings are meant to be shown under UV-light. If a fluorescent painting has damage and needs to be retouched there is a big esthetical problem. The retouched damage is visible under UV-light. The title of this thesis is born out of this last problem: Conservation problems with paintings containing fluorescent layers of paint. The first topic of research for this thesis concerns the composition of these different sorts of paint and pigments. Afterwards, the causes of damage resulting from UV-light –and other factors- were thoroughly analyzed. Finally, a possible remedy is being proposed.

For decades yttrium oxide has been an important material in ceramic industry, but its role in the first synthesized ceramic superconductor, about fifteen years ago, is something unique. In high purity powdered yttria samples luminescent bands which outnumber Raman bands of cubic yttrium oxide were observed. The influence of different processes such as heating, moisturizing and ball milling to luminescent part of the spectra was investigated. Commercial powders of Y2O3, purity better then 99.9 %, produced by three different suppliers were investigated. Raman spectra were recorded with computerized DILOR Z24 triple monochromator with Coherent Innova 100 argon ion laser, operating at 514.5 and 488 nm, which was used for the excitation. The milling was performed in air using Fritschs’ planetary ball mill. The milling time was varied from 1 min to 3 hours. The change of the excitation line helped to separate the luminescent from the Raman part of the spectrum. An extra investigation concerning sample humidity was undertaken. These results confirmed our doubt that the luminescent bands strongly depend on the ad(b)sorbed water. Their intensities notably increased after additional moisturizing with water vapor but decreased and almost disappeared after heating in air at 1100°C. Since water alone does not exhibit such luminescence spectrum, one should consider the mechanism of incorporation of water in the crystal lattice of Y2O3. Although the changes of crystal structure of Y2O3 from cubic to monoclinic structure during ball-milling in argon atmosphere was reported  1 , in our milling experiment performed in air such phase transition was not observed. On the other hand, the luminescent part of the Y2O3 spectrum vanished by milling. High energy transfer from balls to powder could explain the disappearance of the water, caused by local heating, and the absence of the luminescent effect.

We present photoluminescence studies on CdSxSe1– x semiconductor doped glasses with gap energies ranging from about 2 to 3 eV (400– 600 nm). The investigations were performed by near-resonance as well as temperature-dependent resonance Raman spectroscopy. On the basis of the strongly resonant behavior of the deep trap photoluminescence with the excitonic states of the nanocrystallites, we have demonstrated that— besides the effect of photodarkening— inconsistencies in the experimental results of semiconductor doped glasses presented in literature, could be due to changes in the electronic resonance conditions when experimental parameters are changed.

Methods were developed to study delayed light emission (luminiscence) and fluorescence changes in intact leaves of plants. Delayed light emission, detected from plants in darkness, was used to produce images of the plant leaves. The procedure was termed "phytoluminography". The use of the method is suggested for dia- nostic purposes at early stages of disturbances of the leaf tissues, not detectable with the naked eye. The delayed light emission is associated with the photochemistry of photosystem II and the light induced conversion and storage of energy in the thylakoid membrane system of chloroplasts. Fluorescence yield changes were induced by lowering temperature between 20 C and -20 C. The temperature induced fluorescence changes in leaves parallel the temperature induced changes in isolated chloroplasts in reaction preparations mediating photosynthetic electron transport from endogenous water splitting to added NADP. At above freezing temperatures, lowering the temperature at a constant rate of 1 C per minute caused supressed electron transport and increased fluorescence yield which were linearely dependent on the temperature change in frost resistent plants. Repeated freeze-thaw cycles between 20 °C and -20 °C induced variable fluorescence yield changes which were gradually depleated to F0 or Fm when the electron transport was injuried on the oxidizing or on the reduzing side of photosystem II, respectively. The temperature induced fluorescence changes were used to characterize plants with different ability to withstand freezing temperatures. The method also discriminates between plants of different frost resistance, and the method was used in screening for frost tolerance. Diss. (sammanfattning) Umeå : Umeå universitet, 1981, härtill 5 uppsatser. digitalisering@umu