Les polymères de coordination décrits dans cette thèse ont été préparés en accord avec les concepts de la chimie verte par réactions dans l’eau entre les sels de sodium des ligands et les ions lanthanides compris entre La et Lu (sauf Pm) plus Y. Deux types d’échantillons ont été préparés : des monocristaux et des poudres microcristallines. Les structures cristallines ont été résolues sur la base des monocristaux et les poudres microcristallines ont été utilisées pour étudier les propriétés physicochimiques des composés : stabilité thermique, propriétés de luminescence et de magnétisme. Dans nos travaux, quatre systèmes de polymères de coordination ont été étudiés. Ils ont été obtenus à partir de quatre acides : acide chelidonique (H2cda), acide 5-hydroxy-isophthalique (H2hip), acide 5-nitroisophthalique (H2nip) et acide 4-carboxyphenylboronique (Hcpb). Dix nouveaux monocristaux ont été obtenus par diffusions lentes en tubes en U à travers des gels physique (Agar) ou chimiques (TMOS ou TEOS), par diffusion lente en tubes en H à travers de l’eau distillée ou par évaporation lente du filtrat obtenu après la synthèse des poudres microcristallines. Les poudres microcristallines ont été classées sur la base de leurs diagrammes de diffraction des rayons-X. Leurs propriétés de luminescence ou de magnétisme ont été étudiées à l’état solide. Les transferts d’énergie intermétalliques ont été discutés, en particulier pour les ligands H2hip et Hcpb. Les composés hétéro-nucléaires (Gd / Tb et Eu / Tb) ont été préparés pour moduler les propriétés luminescentes de ces composés en variant les proportions relatives en ions lanthanides. Les polymères de coordination à base de terres rares synthétisés et étudiés dans ce manuscrit fournissent des informations intéressantes pour la conception future de matériaux multifonctionnels. / According to the concepts of Green Chemistry, the coordination polymers based on lanthanide ions were prepared by reactions in water between the sodium salts of ligands and lanthanide ions comprised between La and Lu (except Pm) plus Y. Two kinds of samples were prepared : single crystals and microcrystalline powders. The former ones are used to determine the single crystal structure, and the later ones are used to measure the physical-chemical properties : thermal stability, luminescence and magnetism properties. In our work, four ligands were explored: chelidonic acid (H2cda), 5-hydroxy-isophthalic acid (H2hip), 5-nitroisophthalic acid (H2nip) and 4-carboxyphenylboronic acid (Hcpb). As a result, 10 new single crystals were obtained by slow diffusion in U-shape tubes through physical gel (agar) or chemical gels (TMOS or TEOS), by slow diffusion in H-shape tubes through distilled water or by evaporation of the filtrate obtained after the synthesis of the microcrystalline powders. Microcrystalline powders were classified on the basis of their X-ray powder diffraction patterns. Their luminescent properties and magnetic properties were studied in the solid state. Intermetallic energy transfers were also discussed. Especially, for ligands H2hip and H2cpb. Hetero-nuclear compounds (Gd/Tb and Eu/Tb) were also prepared to tune luminescent properties by changing the relative ratios of the lanthanide ions. Lanthanide coordination polymers described in this thesis provide information that could be useful as far as multifunctional materials are targeted.

<p>Еолски седименти представљају идеалан материјал за примену методе луминесцентног датирања. Један од главних разлога је њихов минеролошки састав који углавном чине кварц и фелдспат. Ови минерали поседују читав низ луминесцентних карактеристика који их чине погодним за луминесцентно датирање а поред тога, могуће је релативно једноставно извршити њихову екстракцију и сепарацију од других неминералних састојака. У случају лесних платоа (еолски транспортованих седимената), може се претпоставити да су индивидуална минерална зрна била потпуно изложена сунчевој светлости и да су у довољној мери ресетована пре депозиције. Истраживана секција Велики сурдук на Тителском лесном платоу, изабрана је за датирање, на основу своје моћности, високе стопе седиментације и комплетности које овај локалитет чине најдетаљнијим палеоклиматским архивом последња два глацијално- интерглацијална циклуса у овом делу Европе.<br />Употребом класичног SAR протокола за датирање утврђено је да кварцна зрна са<br />Тителског лесног платоа представљају прецизне дозиметре до ~120 Gy, после чега долази до очигледног засићења сигнала. Највиша утврђена доза фелдспата измерена модификованим SAR пост-IRIR^200,290 протоколом је била 854,0&plusmn;24 Gy. Пост-IRIR^200,290 протокол није утврдио сатурацију код минералних зрна фелдспата, што је умногомо подигло поуздану старосну границу за датирање на секцији Велики сурдук, а највероватније и на осталим лесним профилима у Србији. Примена различитих протокола и мерења аплицираних на различите групе минерала и њихове фракције дају овим истраживањима далекосежан методолошки значај. На овај начин је доказано да у поменутом временском опсегу OSL датирање грубог кварца даје поуздане старосне процене до 35,8&plusmn;3,7 ka док су зрна фелдспата датирана до чак 237,7&plusmn;12,8 ka. Кварц има апсолутно највећу подударност са очекиваним геолошким временом до MIS 2 за разлику од фелдспата који показује бoљу подударност са претпостављеном геолошком хронологијом до MIS 7.</p> / <p>Eolski sedimenti predstavljaju idealan materijal za primenu metode luminescentnog datiranja. Jedan od glavnih razloga je njihov minerološki sastav koji uglavnom čine kvarc i feldspat. Ovi minerali poseduju čitav niz luminescentnih karakteristika koji ih čine pogodnim za luminescentno datiranje a pored toga, moguće je relativno jednostavno izvršiti njihovu ekstrakciju i separaciju od drugih nemineralnih sastojaka. U slučaju lesnih platoa (eolski transportovanih sedimenata), može se pretpostaviti da su individualna mineralna zrna bila potpuno izložena sunčevoj svetlosti i da su u dovoljnoj meri resetovana pre depozicije. Istraživana sekcija Veliki surduk na Titelskom lesnom platou, izabrana je za datiranje, na osnovu svoje moćnosti, visoke stope sedimentacije i kompletnosti koje ovaj lokalitet čine najdetaljnijim paleoklimatskim arhivom poslednja dva glacijalno- interglacijalna ciklusa u ovom delu Evrope.<br />Upotrebom klasičnog SAR protokola za datiranje utvrđeno je da kvarcna zrna sa<br />Titelskog lesnog platoa predstavljaju precizne dozimetre do ~120 Gy, posle čega dolazi do očiglednog zasićenja signala. Najviša utvrđena doza feldspata izmerena modifikovanim SAR post-IRIR^200,290 protokolom je bila 854,0&plusmn;24 Gy. Post-IRIR^200,290 protokol nije utvrdio saturaciju kod mineralnih zrna feldspata, što je umnogomo podiglo pouzdanu starosnu granicu za datiranje na sekciji Veliki surduk, a najverovatnije i na ostalim lesnim profilima u Srbiji. Primena različitih protokola i merenja apliciranih na različite grupe minerala i njihove frakcije daju ovim istraživanjima dalekosežan metodološki značaj. Na ovaj način je dokazano da u pomenutom vremenskom opsegu OSL datiranje grubog kvarca daje pouzdane starosne procene do 35,8&plusmn;3,7 ka dok su zrna feldspata datirana do čak 237,7&plusmn;12,8 ka. Kvarc ima apsolutno najveću podudarnost sa očekivanim geološkim vremenom do MIS 2 za razliku od feldspata koji pokazuje bolju podudarnost sa pretpostavljenom geološkom hronologijom do MIS 7.</p> / <p>Aeolian sediments represent an ideal material for the application of the luminescence dating method. One of the main reasons is their mineralogical composition which consists mainly of quartz and feldspars. These minerals possess a whole range of luminescence characteristics that make them suitable for luminescence dating, and in&nbsp;&nbsp; addition, it is relatively easy to extract and separate them from other non-mineral ingredients. In the case of loess plateaus (eolically transported sediments), it can be assumed that individual mineral grains were completely exposed to sunlight and were sufficiently bleached before deposition. The investigated section Veliki surduk on the Titel loess plateau was chosen for dating, based on its thicknes, the high rate of sedimentation and completeness which makes this site one of the most detailed paleoclimatic archives of the last two glacial and interglacial cycles in this part of Europe.<br />Using the classic SAR protocol for dating, it has been found that the quartz grains from the Titel loess plateau are precise dosimeters up to ~120 Gy, followed by an apparent saturation of the signal. The highest established dose of feldspars measured by the modified SAR postIRIR^200,290 protocol was 854.0&plusmn;24 Gy. The post-IRIR^200,290 protocol did not determine the saturation of feldspar minerals, which has largely raised the age limit for luminescence dating at the Veliki surduk section, and most probably, also on other loess profiles in Serbia. The application of various protocols and measurements applied to different groups of minerals and their fractions give these research a far-reaching methodological significance. In this way, it has been proven that in the mentioned time range, OSL dating of coarse grain quartz yields reliable age estimates up to 35.8&plusmn;3.7 k while the feldspar grains are dated to as high as 237.7&plusmn;12.8 ka. Quartz has the highest match with the expected geological age to MIS 2 as opposed to feldspar, which shows better correspondance with the assumed geological chronology to MIS 7.</p>

Ce mémoire se penche sur les propriétés photophysiques de différents complexes métalliques, particulièrement leur changement de structure moléculaire, leur état fondamental ainsi que leur état émissif par spectroscopie Raman et de luminescence. Ces techniques spectroscopiques peuvent être utilisées pour détecter et suivre des changements, comme des transitions de phase structurales. Pour ce mémoire, quatre composés seront étudiés par spectroscopie. Le premier est un composé de nickel(II) ayant un ligand azoture pontant, dont l’agencement spatial change avec une diminution de la température, cette dernière causant un changement dans la susceptibilité magnétique du composé. Les spectres obtenus montrent bel et bien un changement abrupt dans le pic du cisaillement du ligand azoture aux environs de 210 K. Les mesures à pression variable montrent également un changement soudain, entre 1 bar et 1,1 kbar. Le deuxième composé contient deux centres de manganèse(II) ayant chacun une coordination inhabituelle de sept, ce qui n’est pas souvent observé. Il s’avère que la spectroscopie Raman n’est pas assez précise pour mesurer un changement dans ce composé. Tous les déplacements de maxima des bandes mesurés se retrouvaient dans un intervalle de 1 cm-1 ; la résolution de l’appareil limite la confirmation s’il y a bel et bien une transition de phase. Les spectres de luminescence ne montrent pas de changement évident non plus. Le troisième composé est un complexe de platine plan carré qui possède des interactions platine(II)-platine(II), et qui montre un spectre de luminescence. Des complexes similaires ont déjà été étudiés par d’autres membres du groupe de recherche; il s’agit donc de compléter la banque de résultats et de comparer avec les données connues. Les résultats ne montrent aucun déplacement dans la transition, mais un amincissement du pic, ce qui est comparable aux données antérieures. Le quatrième composé est également un complexe de platine(II) plan carré, qui montre un spectre de luminescence. Un composé similaire a déjà été étudié par un étudiant de notre groupe de recherche, en rapportant un changement soudain dans le pic de luminescence. Les spectres mesurés montrent un changement de structure, qui se fait de manière graduelle plutôt que soudainement. Ce mémoire est donc axé sur la spectroscopie Raman et de luminescence à températures et pression variables. Les spectres mesurés, notamment les déplacements des maxima, donnent de l’information sur des changements de structure, de l’état fondamental et de l’état émissif. / This master’s thesis is focused on the vibrational spectroscopy of coordination compounds displaying or undergoes spatial or structural changes as well as variations in their ground state and their emitting state, studied via Raman and luminescence spectroscopy. These spectroscopic techniques can be used to detect and observe various changes, such as phase transitions. In this thesis, four compounds will be studied. The first one is a nickel(II) compound featuring azide bridging ligand, whose spatial arrangement changes by lowering the temperature, causing also a change in the magnetic susceptibility of the compound. The spectra we measured show clearly a sudden change in the scissoring vibration for the azide, at temperatures around 210 K. The variable pressure data we collected also show a sudden change between 1 bar and 1,1 kbar. The second compound contains two manganese(II) centers, both having a coordination number of seven, which is rarely seen for this metal center. Raman spectroscopy isn’t accurate enough to detect any structural changes. Any changes of band maxima were under 1 cm-1, at the limits of the instrument’s resolution. Luminescence graphs do not show anything in particular. The third compound is a square planar platinum(II) complex showing platinum(II)-platinum(II) interactions, influencing its luminescence spectrum. Similar complexes have already been studied by other members of this research group; this research will therefore add results to those we already have, and will be compared to these results. The results don’t show any transition, but the peaks are narrowing at low temperature, a behaviour similar to other systems. The fourth compound is also a square planar platinum(II) complex showing a luminescence spectrum. A similar complex has already been studied by a student in this research group, reporting a sudden shift in the luminescence peak. The spectrum shows indeed a structural change, but this change is gradual instead of sudden. This thesis is focusing on variable temperature and pressure Raman and luminescence spectroscopy. The experimental spectra show information about structural change, fundamental state and emissive state.

In this thesis, the effect of the sample properties on the characteristics of the hot carrier luminescence in graphene is investigated. The present work focuses on the two main issues described below. The first issue is the modification effects of near-infrared pulsed laser excitation on graphene. For excitation fluences several orders of magnitude lower than the optical damage threshold, the interaction with ultrafast laser pulses is found to cause a stable change in the properties of graphene. This photomodification also results in a decrease of the hot photoluminescence intensity. The detailed analysis shows that ultrafast photoexcitation leads to an increase in the local level of hole doping, as well as a change in the mechanical strain. The variation of doping and strain are linked with the enhanced adsorption of atmospheric oxygen caused by the distortion of the graphene surface. These findings demonstrate that ultrashort pulsed excitation can be invasive even if a relatively low laser power is used. Secondly, the variation of the hot photoluminescence intensity with the increasing charge carrier density in graphene is investigated. The electro-optical measurements performed using graphene field-effect transistors show a strong dependence of the photoluminescence intensity on the intrinsic carrier concentration. The emission intensity has a maximum value in undoped graphene and decreases with the increasing doping level. The theoretical calculations performed using a refined two-temperature model suggest that the reduction of the photoluminescence intensity is caused by an increase in the hot carrier relaxation rate. The modification of the carrier relaxation dynamics caused by photoinduced doping is probed directly using the two-pulse correlation measurements. The discovered sensitivity of the hot photoluminescence to the intrinsic carrier concentration can be utilised for spatially-resolved measurements of the Fermi level position in graphene samples, offering an advantage in resolution and speed.

A contactless method using a novel design of the experimental cell for formation of porous silicon with morphological gradient is reported. Fabricated porous silicon layers show a large distribution in porosity, pore size and depth along the radius of the samples. Symmetrical arrangements of morphology gradient were successfully formulated radially on porous films and the formation was attributed to decreasing current density radially inward on the silicon surface exposed to Triton (R) X-100 containing HF based etchant solution. Increasing the surfactant concentration increases the pore depth gradient but has a reverse effect on the pore size distribution. Interestingly, when dimethyl sulfoxide was used instead of Triton (R) X-100 in the etchant solution, no such morphological gradients were observed and a homogeneous porous film was formed.

Membranes with a pore size rating of 0.2μm are recommended for the sterilisation of liquids by filtration and are validated for this purpose by a retention test with Pseudomonas diminuta. Practices for retention testing were found to vary among the membrane manufacturers and only one type of commercial 0.2μm rated membrane was found to reliably retain P. diminuta. The retention for P. diminuta given by experimental grafted membranes was studied and was sometimes higher than that given by non-grafted membranes due to obstruction of the pores by graft material. The dimensions for individual cells of P. diminuta was studied by scanning electron microscopy and a rapid electronic method. Bacteria of larger dimensions than the pore size rating of experimental membranes were found in test permeates. It was shown that cells from an aerated P. diminuta culture were larger than cells from a similar but stationary culture. A retention test procedure for 0.2 μm rated membranes using cross-flow filtration was developed. The procedure simulated process conditions and enabled tubular ceramic monolithic membranes and flat-sheet membranes to be retention tested with P. diminuta. It is feasible that a standard retention test using cross-flow filtration can be developed. The time needed for results from current retention test procedures to become available is a consequence of using traditional cultural techniques for permeate analysis. Test procedure were developed using three popular methods for the rapid detection and enumeration of bacteria (ATP luminescence, impedance microbiology and the DEFT) for the detection and enumeration of P. diminuta in retention test permeates. The method using ATP luminescence was found to be the most applicable. The development of a bioluminescent strain of P. diminuta through genetic engineering will enable the rapid, sensitive and straightforward retention testing of 0.2 μm rated membranes. Retention tests using a bioluminescent strain of Escherichia coli containing the structural genes for bacterial luciferase indicated that the proposed test is feasible. Developments were made towards cloning the same genes into P. diminuta. The use of all bioluminescent micro-organisms for membrane retention testing is the subject of a patent application and a proposal for a three year SERC research grant.

Exploration of novel lanthanide fluoride framework materials in inorganic-organic hybrid systems under solvothermal conditions towards development of new luminescent materials is discussed. X-ray single crystal and powder diffraction methods have been used as crystallographic characterisation techniques. Determination and study of luminescence properties for selected hybrid materials has also been carried out. The first organically templated luminescent lanthanide fluoride framework, [C₂N₂H₁₀]₀.₅ [Ln₂F₇] (Ln= Nd, Tb, Dy, Ho, Er, Yb and Lu), has been synthesised and characterised. This structure type consists of a three-dimensional yttrium fluoride framework incorporating two similar, but crystallographically distinct, yttrium sites. Photoluminescence studies of [C₂N₂H₁₀]₀.₅ [Y₂F₇]: Ln³⁺ (Ln³⁺ = Gd³⁺, Eu³⁺ and Tb³⁺) have been explored and characteristic luminescence emissions are reported. An inorganic-organic hybrid indium fluoride and its scandium fluoride analogue, [C₄H₁₄N₂][MF₅](M=In and Sc) is reported. The structure consists of infinite trans vertex sharing (InF₅)[subscript(∞)] chains, which are linked via H-bonded organic moieties. The scandium and fluorine local environments of [C₄H₁₄N₂][ScF₅] are characterised by ¹⁹F, and ⁴⁵Sc solid-state MAS NMR spectroscopies. A single scandium site has been confirmed by ⁴⁵Sc MAS NMR. ¹⁹F MAS NMR clearly differentiates between bridging and terminal fluorine. The photoluminescence properties of these complexes, [C₄H₁₄N₂][In[subscript(1-x)] Ln[subscript(x)]F₅] (Ln=Tb and/or Eu), have been explored. The optimum composition for Eu³⁺ doped samples occurs at x = 0.05 Eu³⁺ and the “asymmetry ratio” of R = I₅₉₀/I₆₁₅ ( ⁵D₀ → ⁷F₂ and ⁵D₀ → ⁷F₁) gives a clear picture of the sensitivity for crystal field of the compound. For x = 0.08 Tb³⁺, a strong down-conversion fluorescence corresponding to ⁵D₄ → ⁷F₅ (green at 543.5 nm) occurs. In addition, a Tb³⁺/Eu³⁺ co-doped sample exhibits a combination of green (Tb³⁺) and orange (Eu³⁺) luminescence, with Tb³⁺ enhancing the emission of Eu³⁺ in this host. Exploration of novel indium, aluminium, and zirconium fluoride crystal structures with potential luminescent properties has also been undertaken. A chiolite-like phase K₅In₃F₁₄ (space group P4/mnc) has been synthesised. No phase transition occurs over the temperature range 113K< T< 293 K, as has been seen in other chiolite-like structures. An organically templated indium fluoride, [NH₄]₃[C₆H₂₁N₄]₂[In₄F₂₁] has been prepared; this features the trimeric unit [In₃F₁₅]³⁻ which appears to be the first of its type in a metal fluoride. A new hybrid fluoride, Sr[N₂C₂H₁₀]₂[Al₂F₁₂].H₂O has been synthesised. Because the ionic radius of Eu²⁺ is similar to that of Sr ²⁺ this may be a potential host for blue luminescent Eu²⁺. The new material KZrF₅.H₂O shows pentagonal-bipyramidal geometry of Zr⁴⁺ with a polar space group, Pb2₁m, which may potentially have ferroelectric properties.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Earth Sciences / Master / Master of Philosophy

This thesis is focused on understanding the interactions between molecules and surface-enhanced Raman scattering (SERS) substrates that are typically unresolved due to the diffraction limit of light. Towards this end, we have developed and tested several different sub-diffraction-limited imaging techniques in order to observe these interactions. First, we utilize an isotope-edited bianalyte approach combined with super-resolution imaging via Gaussian point-spread function fitting to elucidate the role of Raman reporter molecules on the location of the SERS emission centroids. By using low concentrations of two different analyte molecules, we find that the location of the SERS emission centroid depends on the number and positions of the molecules present on the SERS substrate. It is also known that SERS enhancement partially results from the molecule coupling its emission into the far-field through the plasmonic nanostructure. This results in a particle-dictated, dipole-like emission pattern, which cannot be accurately modeled as a Gaussian, so we tested the applicability of super-resolution imaging using a dipole-emission fitting model to this data. To test this model, we first fit gold nanorod (AuNR) luminescence images, as AuNR luminescence is primarily coupled out through the longitudinal dipole plasmon mode. This study showed that a three-dimensional dipole model is necessary to fit the AuNR emission, with the model providing accurate orientation and emission wavelength parameters for the nanostructure, as confirmed using correlated AFM and spectroscopy. The dipole fitting technique was next applied to single- and multiple-molecule SERS emission from silver nanoparticle dimers. We again found that a three-dimensional dipole PSF was necessary to accurately model the emission and orientation parameters of the dimer, but that at the single molecule level, the movement of the molecule causes increased uncertainty in the orientation parameters determined by the fit. Finally, we describe progress towards using a combined atomic force/optical microscope system in order to position a carbon nanotube analyte at known locations on the nanoparticle substrate. This would allow for the simultaneous mapping of nanoparticle topography and exact locations of plasmonic enhancement around the nanostructure, but consistently low signal-to-noise kept this technique from being viable. / text