Electronic inhomogeneities play an important role in the definition of physical properties of correlated systems. To study these inhomogeneities one has to use local probe techniques which can distinguish electronic, magnetic and structural variations at the nanoscale. In the present work the high-field electron spin resonance technique (HF-ESR) is used to probe electronic and magnetic inhomogeneities in two transition-metal element based systems with very different properties. The first system is an iron based hightemperature superconductor, namely a member of a so called 1111-family, the (La,Gd)O1−xFxFeAs compound. Our HF-ESR spectroscopy study on Gd3+ ion has revealed that this material exhibits anisotropic interaction between Gd and Fe layers, which is frustrated in the absence of an external magnetic field. Moreover, the study of the superconducting samples has shown a coexistence of a static short range magnetic order with superconductivity up to high doping levels. The second system is a lightly hole doped cubic perovskite LaCoO3. Here, our HF-ESR investigation, complemented with static magnetometry and nuclear magnetic resonance techniques, has established that the hole doping induces a strong interaction between electrons on neighboring Co ions which leads to a collective high-spin state, called a spin-state polaron. These polarons are inhomogeneously distributed in the nonmagnetic matrix. This thesis is organized in three chapters. The first chapter gives basic ideas of magnetism in solids, focusing on the localized picture. The aim of the second chapter is to introduce the method of ESR. The third chapter is dedicated to the study of 1111-type iron arsenide superconductors. In the first part X-band (9.5 GHz) ESR measurements on 2% and 5% Gd-doped LaO1−xFxFeAs are presented. In the second part a combined investigation of the properties of GdO1−xFxFeAs samples by means of thermodynamic, transport and high-field electron spin resonance methods is presented. The last, fourth chapter presents the investigation of the unexpected magnetic properties of lightly hole-doped LaCoO3 cobaltite by means of the electron spin resonance technique complemented by magnetization and nuclear magnetic resonance measurements.

<p>Cilj istraživanja doktorske disertacije je bio da se u<br />konitnuitetu ispita sadržaj ukupnih fenola, fenolnih kiselina i<br />anitoksidativna aktivnost (antiradikalska aktivnost na DPPH i<br />hidroksil radikale) u toku proizvodnje slada i piva (u ječmu,<br />namočenom ječmu, zelenom sladu, sladu, sladovini, ohmeljenoj<br />sladovini, sladovini tokom fermentacija, mladom pivu i pivu)<br />proizvedenih od tri priznate sorte pivskog ječma: NS 525, NS<br />565 i NS 583.<br />Sadržaj ukupnih fenola u uzorcima ječma je bio: NS 525 -<br />0,76; NS 565 - 0,75 i NS 583 - 0,70 mg GAE/g suve materije.<br />Sadržaj ukupnih fenola u svim proizvednim sladovima (0,96;<br />0,94 i 0,91 mg GAE/g suve materije za NS 525; NS 565 i NS<br />583) je bio vi&scaron;i od sadržaja u ječmu. Sorta NS 525 je imala<br />najvi&scaron;i sadržaj ukupnih fenola tokom svih faza sladovanja, dok<br />su sorte NS 565 i NS 583 imale niže sadržaje ukupnih fenola.<br />Najniži sadržaj ukupnih fenola imala je sorta NS 583.<br />U svim ispitivanim sortama ječma ferulna, p-kumarinska i<br />vanilinska kiselina su bile dominantne u uzorcima ječma,<br />tokom sladovanja i u proizvedenom sladu.<br />Sadržaj ukupnih fenolnih kiselina u ječmu je iznosio za sortu<br />NS 525 - 200,98; NS 565 - 184,10 i za NS 583 &ndash; 177,27 &mu;g/g suve<br />materije. Sadržaj ukupnih fenolnih kiselina je rastao kod svih<br />ispitivanih sorti tokom močenja i dostigao maksimum u toku<br />prvog dana klijanja za NS 525 &ndash; 548,31; NS 565 &ndash; 518,65 i NS<br />583 &ndash; 517,17 &mu;g/g suve materije. Dobijeni rezultati su pokazali<br />da je proces sladovanja imao značajan uticaj na sadržaj<br />pojedinačnih i ukupnih fenolnih kiselina.<br />Sorta NS 525 je imala najvi&scaron;u antiradikalsku aktivnost na<br />DPPH radikale (EC50 za NS 525 - 0,658; NS 565 - 0,667 i NS<br />583 - 0,758 mg/ml) &scaron;to pokazuje da sorta ječma ima uticaja na<br />antiradikalsku aktivnost na DPPH radikale. Za ispitivane sorte<br />ječma, antiradikalska aktivnost na DPPH radikale se povisila<br />značajno tokom močenja. U proizvedenim sladovima<br />antiradikalska aktivnost na DPPH radikale bila je vi&scaron;a nego u<br />ječmu. Trend porasta i smanjenja antiradikalske aktivnosti na<br />DPPH radikale tokom sladovanja je bio isti za sve ispitivane<br />sorte ječma.<br />Antiradikalska aktivnost na hidroksil radikale, izražena kao<br />EC50 vrednost, u ispitivanim sortama ječma je iznosila: NS 525<br />&ndash; 0,352; NS 565 &ndash; 0,385 i NS 583 &ndash; 0,455 mg/ml. Može se<br />zaključiti da je sorta NS 525 imala najvi&scaron;u antiradikalsku<br />aktivnost na hidroksil radikale. Antiradikalska aktivnost na<br />hidroksil radikale se znatno povisila tokom močenja. U<br />proizvedenom sladu je antiradikalska aktivnost na hidroksil<br />radikale bila vi&scaron;a nego u ječmu. Trend porasta i smanjenja<br />antiradikalske aktivnosti na hidroksil radikale tokom<br />sladovanja je bio isti za sve ispitivane sorte ječma.<br />Sorta NS 525 je imala najvi&scaron;i sadržaj ukupnih fenola kao i<br />najvi&scaron;u antioksidativnu aktivnost tj. DPPH i hidroksil<br />antiradikalsku aktivnost. Ovi rezultati pokazuju da sorta<br />ječma može da utiče na antiradikalske osobine slada. Sorta NS<br />525 je imala najvi&scaron;i sadržaj ukupnih fenola, ukupnih fenolnih<br />kiselina i najvi&scaron;u antiradikalsku aktivnost na DPPH i hidroksil<br />radikale u toku sladovanja.<br />U svim proizvedenim sladovinama, ohmeljenim sladovinama i<br />pivima, ferulna, p-kumarinska, vanilinska i sinapinska kiselina<br />su imale najvi&scaron;e sadržaje. Sadržaj svih ispitivanih fenolnih<br />kiselina je povi&scaron;en nakon hmeljenja. Najvi&scaron;i ukupni sadržaj<br />fenolnih kiselina je odre&ntilde;en u ohmeljenim sladovinama (NS<br />525 - 461,41, NS 565 - 426,22 i NS 583 - 423,56 &mu;g/100ml).<br />Sadržaj ukupnih fenolnih kiselina je u svim proizvedenim<br />pivima bio niži u odnosu na odgovarajuće ohmeljene sladovine.<br />U sladovini proizvedenoj iz slada NS 525 je odre&ntilde;ena najvi&scaron;a<br />antiradikalska aktivnost na DPPH i hidroksil radikale &scaron;to<br />ukazuje da antiradikalska aktivnosti komponenti slada ima<br />uticaja na antiradikalsku aktivnost proizvedene sladovine. U<br />ispitivanim sladovinama, nakon hmeljenja se znatno povisila<br />antiradikalska aktivnost na DPPH i hidroksil radikale.<br />Antiradikalska aktivnost na DPPH i hidroksil radikale se<br />smanjila tokom glavne i naknadne fermentacije.<br />U sladovini proizvedenoj od slada NS 525 sa najvi&scaron;im<br />sadržajem ukupnih fenola i ukupnih fenolnih kiselina<br />odre&ntilde;ena je najvi&scaron;a antiradikalska aktivnost na DPPH i<br />hidroksil radikale. Tokom proizvodnje piva sadržaj ukupnih<br />fenola se blago smanjio, &scaron;to ukazuje da je proces proizvodnje<br />imao uticaja na njihov sadržaj. Trend smanjenja<br />antiradikalske aktivnosti na DPPH i hidroksil radikale<br />odgovara smanjenju sadržaja ukupnih fenola i ukupnih<br />fenolnih kiselina tokom procesa proizvodnje piva.<br />Primenjena GC-MS metoda za odre&ntilde;ivanje sadržaja fenolnih<br />kiselina tokom procesa proizvodnje slada i piva se pokazala<br />kao osetljiva, specifična i dobre ponovljivosti. Može se<br />primeniti za odre&ntilde;ivanje sadržaja fenolnih kiselina u ječmu,<br />namočenom ječmu, zelenom sladu, sladu, sladovini, ohmeljenoj<br />sladovini, tokom fermentacije i u pivu.<br />Sadržaj ukupnih fenola, fenolnih kiselina i antioksidativna<br />aktivnost slada, koji se koristi za proizvodnju piva, imaju<br />značajan uticaj na antioksidativnu aktivnost piva.<br />Razumevanje promena sadržaja fenolnih kiselina i<br />antioksidativne aktivnosti tokom proizvodnje slada i piva može<br />nam pružiti vredne informacije o za&scaron;titi endogenih<br />antioksidanata u proizvodnji piva. Na taj način mogu se<br />proizvoditi piva sa vi&scaron;om antioksidativnom aktivno&scaron;ću i prema<br />tome i povi&scaron;enom otporno&scaron;ću prema lipidnoj oksidaciji i<br />starenju piva.</p> / <p>Studies carried out in the frame of the doctorial thesis<br />aimed at continuous determination of the content of<br />total phenolics, phenolic acids and antioxidant activity<br />(antiradical activity on DPPH and hydroxyl radicals)<br />during malt and beer production (in barley, steeped<br />barley, green malt, malt, wort, hopped wort,<br />fermenting wort, green beer, and beer) produced from<br />three accepted brewer&rsquo;s barley varieties: NS 525, NS<br />565, and NS 583.<br />The total phenolics content in the barley samples was<br />0.76 for NS 525, 0.75 for NS 565 and 0.70 mg GAE/g<br />dry matter (d.m.) for NS 583. Higher content of total<br />phenolics was determined in the malt samples in<br />comparison with the barley samples: (0.96, 0.94, and<br />0.91 mg GAE/g d.m. for NS 525, NS 565, and NS 583,<br />respectively). Variety NS 525 was the highest in total<br />phenolics content during all stages of malting when<br />compared to the other varieties. The lowest content of<br />total phenolics was found in the variety NS 583.<br />In all examined samples, ferulic, p-coumaric and<br />vanillic acid dominated in the barley samples, during<br />malting and in the produced malts.<br />Content of total phenolic acids in the barley samples<br />was 200.98 for NS 525, 184.10 for NS 565 and 177.27<br />mg/g d.m. for NS 583. During steeping, the content of<br />total phenolic acids increased for all samples reaching<br />the maximum at the first day of germination (NS 525 &ndash;<br />548.31; NS 565 &ndash; 518.65, and NS 583 &ndash; 517.17 &mu;g/g<br />d.m.). The obtained results revealed that the malting<br />process had significant impact on the content of total<br />and individual phenolic acids.<br />Variety NS 525 showed the highest antiradical activity<br />on DPPH radicals (EC50 for NS 525 was 0.658, for NS<br />565 0.667, and for NS 583 0.758 mg/ml) indicating that<br />barley variety influences the antiradical activity on<br />DPPH radicals. Antiradical activity on DPPH radicals<br />significantly increased during steeping for all<br />investigated barley varieties. Higher antiradical<br />activity on DPPH radicals was determined in<br />produced malts when compared to corresponding<br />barley varieties. Similar increasing and decreasing<br />trends in the antiradical activity on DPPH radicals<br />during malting were observed in all investigated<br />barley varieties.<br />The antiradical activity on hydroxyl radicals,<br />expressed as EC50 value, in investigated barley<br />varieties, was: 0.325 for NS 525, 0.385 for NS 565, and<br />0.455 mg/ml for NS 583. It can be concluded that<br />barley variety NS 525 showed the highest antiradical<br />activity on hydroxyl radicals. The antiradical activity<br />on hydroxyl radicals significantly increased during<br />steeping. Higher antiradical activity on hydroxyl<br />radicals was determined in produced malts when<br />compared to corresponding barley varieties. Similar<br />increasing and decreasing trends in the antiradical<br />activity on hydroxyl radicals during malting were<br />observed in all investigated samples.<br />Variety NS 525 had the highest content of total<br />phenolics and exhibited the highest antioxidant<br />activity that is antiradical activity on DPPH and<br />hydroxyl radicals. These results suggest that variety<br />can influence the malt antiradical properties. Variety<br />NS 525 was the highest in total phenolics content, total<br />phenolic acids content and antiradical activity on<br />DPPH and hydroxyl radicals during malting.<br />The highest contents of ferulic, p-coumaric, vanillic,<br />and sinapic acids were determined in all wort, hopped<br />wort and beer samples. Increased contents of all<br />phenolic acids were observed after hopping. The<br />highest content of total phenolic acids was determined<br />in the hopped worts (461.41 for NS 525, 426.22 for NS<br />565, and 423.56 &mu;g/100 ml for NS 583. The beers<br />contained less total phenolic acids when compared to<br />the corresponding hopped worts.<br />Wort produced from NS 525 malt showed the highest<br />antiradical activity on DPPH and hydroxyl radicals<br />which indicates that the antiradical activity of malt<br />components affects the antiradical activity in produced<br />wort. After hopping, antiradical activity on DPPH and<br />hydroxyl radicals significantly increased in all worts.<br />The antiradical activity on DPPH and hydroxyl<br />radicals decreased during primary and secondary<br />fermentation.<br />Wort produced from NS 525 malt contained the<br />highest total phenolic content, total phenolic acids<br />content and showed the highest antiradical activity on<br />DPPH and hydroxyl radicals. During beer production,<br />content of total phenolic compounds slightly decreased<br />which indicates that production process had an<br />influence on their content. Similar decreasing trends<br />between the antiradical activity on DPPH and<br />hydroxyl radicals and the contents of total phenolics<br />and total phenolic acids during beer production were<br />observed.<br />The applied GC-MS method for determination of<br />phenolic acids contents during malt and beer<br />production was sensitive, specific and had good<br />repeatability. It can be used for determination of<br />phenolic acids content in barley, steeped barley, green<br />malt, malt, wort, hopped wort, during fermentation<br />and in beer.<br />The content of total phenolics, phenolic acids and<br />antioxidant activity of malt used for beer production<br />have significant influence on the beer antioxidant<br />activity. Understanding how the phenolic acids and<br />antioxidant activity change during malt and beer<br />production can provide valuable information about<br />the protection of endogenous antioxidants in beer<br />production. In this way, the production of beer with<br />enhanced antioxidant activity is possible and therefore<br />higher resistance to lipid oxidation and longer shelflife<br />could be introduced.</p>

Neste trabalho foi desenvolvido um programa para simular espectros de ressonância paramagnética eletrônica (RPE) de onda contínua de amostras policristalinas para tensores não coincidentes. O Hamiltoniano de spin utilizado inclui os tensores anisotrópicos g, interação hiperfina, divisão de campo zero e quadrupolar e o termo Zeeman nuclear isotrópico. O programa inclui várias tecnologias novas, tais como: segmentação de campo com teoria de perturbação de autocampo para localizar as posições de campo ressonante, os métodos de distribuição Espiral e Repulsão para determinar o conjunto de orientações e a interpolação bidimensional triangular para reduzir o número de orientações computadas. A conjunção desses algoritmos podem aumentar a velocidade e a precisão das simulações, especialmente na simulação de espectros de sistemas de spin de dimensões grandes. O programa foi testado em algumas situações reais e o resultado obtido pode ser considerado, em alguns casos, equivalente aos programas comerciais e, em outros casos, de qualidade superior. / A computer program to simulate continuous wave electron paramagnetic resonance (EPR) powder spectra for noncoincident tensors has been developed. The spin Hamiltonian used includes anisotropic g, hyperfine interaction, zero field splitting and quadrupolar tensors and isotropic nuclear Zeeman term. The program includes a number of new technologies such as: field positions, spiral and repulsion methods for determining a set of orientations and triangular bidimensional interpolation to reduce the number of computed orientations. The conjunction of these algorithms can greatly increase the speed and the accuracy of simulations; especially in simulating powder spectra of spin systems of large dimensions. The program has been tested in some real situations and the obtained result can be considered, in some cases, equivalent to that of commercial software, in other cases, of superior quality.

In the ejecta from ONe novae outbursts nuclei up to A~40 are observed. The 30P(p,γ)31S reaction is thought to be the bottleneck for the production of all elements heavier than sulphur. However, due to uncertainties in the properties of key proton-unbound resonances the reaction rate is not well determined. In this thesis work, excited states in 31S were populated via the 28Si(4He,n) light-ion fusion-evaporation reaction and the prompt electromagnetic radiation was then detected with the GAMMASPHERE detector array. This γ-ray spectroscopy study, and comparisons with the stable mirror nucleus 31P, allowed the determination of the 31S level structure below the proton-emission threshold and also of the key proton-unbound states for the 30P(p,γ)31S reaction. In particular, transitions from key, low-spin states were observed for the first time. This new information was then used for the re-evaluation of the 30P(p,γ)31S reaction in the temperature range relevant for ONe novae. The newly calculated rate is higher than previous estimates implying a greater flux of material processed to high-Z elements in novae. Astrophysical X-ray bursts are thought to be a result of thermonuclear explosions on the atmosphere of an accreting neutron star. Between these bursts, energy is thought to be generated by the hot CNO cycles. The 15O(α,γ)19Ne reaction is one reaction that allows breakout from these CNO cycle and into the rp-process to fuel outbursts. The reaction is expected to be dominated by a single 3/2+ resonance at 4.033 MeV in 19Ne, however, limited information is available on this key state. This thesis work reports on a pioneering study of the 20Ne(p,d)19Ne reaction in inverse kinematics performed at the Experimental Storage Ring (ESR) as a means of accessing the 4.033-MeV state in 19Ne. The unique background free, high luminosity conditions of the ESR were utilised for this, the first transfer reaction performed at the ESR. The results of this pioneering test experiment are presented along with suggestions for future measurements at storage ring facilities.

Depuis une quarantaine d'années le développement des Sciences Physiques a permis à la Préhistoire d'aujourd'hui d'élargir son champ d'investigation. En effet, la physique nucléaire a fourni des méthodes de datation absolue qui sont venues s'ajouter aux méthodes plus traditionnelles que sont la paléontologie humaine, la typologie ou encore la sédimentologie.<br /><br /> Dans ce travail, nous avons choisi d'utiliser la méthode de la Résonance de Spin électronique pour dater des sites acheuléens et moustériens du midi méditerranéen et ce pour plusieurs raisons.<br /><br /> La première est que c'est une méthode nouvelle.<br /><br /> La deuxième est qu'elle couvre une période qui s'étend pratiquement sur tout le Quaternaire et nous nous sommes attachés à vérifier que la méthode ESR pouvait fournir des repères chronologiques pour des périodes que les autres méthodes de datation absolue ne permettent pas ou rarement de dater.<br /><br /> En effet, la méthode du C14 a permis d'établir une chronologie détaillée pour les sites du Paléolithique supérieur. Mais compte tenu de la période relativement courte de cet élément, T = 5730 ans, il est difficile d'effectuer des datations allant au-delà de 35-40 000 ans.<br /><br /> Les méthodes de datation utilisant les déséquilibres des familles de l'uranium (Th-230/U-234, Pa-231/U-235), permettent de dater jusqu'à 300 000 et 150 000 ans respectivement.<br /><br /> Certains sites plus anciens de l'Afrique de l'Est notamment ont été datés par la méthode K/Ai grâce aux cendres volcaniques qu'ils contiennent. Il est également possible d'utiliser la méthode des traces de fission pour des sites anciens. Malheureusement, la rareté des cendres volcaniques et des minéraux formés à haute température comme le zircon constitue un obstacle à l'utilisation de ces méthodes.<br /><br /> Donc, pour dater des sites plus anciens que 300 000 ans, il fallait développer de nouvelles méthodes. C'est le cas de la TL et de l'ESR, qui reposent sur le même principe comme nous allons le voir.<br /> La TL s'avère assez précise pour dater des céramiques, roches volcaniques ou des silex brûlés.<br /><br /> Quant à la méthode ESR, elle s'applique à plusieurs minéraux comme le quartz, l'aragonite mais essentiellement à la calcite issue des planchers stalagmitiques qui sont nombreux dans les sites du Midi-méditerranéen.<br /><br /> Ce travail se compose de 2 parties.<br /><br /> La première est consacrée à la méthode ESR/<br /><br /> La deuxième concerne l'application de la méthode à la datation de sites préhistoriques.

la méthode de datation ESR est une méthode paléodosimétrique, c'est-à-dire qu'elle utilise les échantillons comme des dosimètres naturelsqui ont enregistré la dose totale de radiation qu'ils ont reçue depuis leur formation ou leurenfouissement. Comme les méthodes de la luminescence, la méthode ESR est fondée sur l'accumulation au cours du temps d'électrons piégés dans des défauts du système cristallin des minéraux sous l'effet de la radioactivité naturelle. L'équation d'âge peut s'exprimer classiquement comme ceci : la dose totale de radiation D classiquement appelée paléodose est fonction de la dose de radiation reçue annuellement par l'échantillon da et du temps. Pour réaliser une datation ESR, il faut donc déterminer ces deux paramètres, paléodose et dose<br />annuelle.<br />La détermination de la paléodose se fait en utilisant la spectrométrie ESR. En fait, on va s'intéresser aux caractéristiques magnétiques des échantillons et notamment au paramagnétisme des électrons célibataires piégés. Les électrons sont animés d'un mouvement de rotation sur eux-mêmes, appelé spin, et qu'ils possèdent une charge négative, le spin entraîne la formation d'un moment magnétique. Si on place un électron dans un champ magnétique intense, il va s'orienter par rapport à ce dernier et deux positions vont alors être possible en fonction du sens de rotation. A ces deux orientations vont correspondre deux niveaux d'énergie, appelés niveaux Zeeman. Si maintenant on envoie une micro-onde sur notre échantillon, on va pour une certaine valeur de fréquence de celle-ci pouvoir induire des transitions entre ces deux niveaux d'énergie. On observera alors une absorption d'une partie de l'énergie de la micro-onde et la dérivée première de ce signal d'absorption correspond au signal mesuré par ESR. Chaque signal ERS est caractéristique de la matière analysé et fournira des informations sur la position au sein du cristal de l'électron correspondant.<br />Pour déterminer la paléodose, on utilise la méthode dite de l'addition. On vieillit artificiellement l'échantillon en l'irradiant à des doses croissantes puis on trace un diagramme reportant la variation de l'intensité ESR du signal considéré en fonction de la dose d'irradiation ajoutée. L'extrapolation de la courbe de croissance obtenue à une ordonnée zéro fournit la paléodose.<br />La détermination de la dose annuelle peut se fait en déterminant la contribution de chaque type de rayonnement (α, β, γ, cosmiques) auxquelles est soumis l'échantillon durant une année. K est un facteur correctif lié au fait que les rayons alpha entraînent la création de moins d'électrons piégés que les rayons bêta ou gamma. On peut également exprimer la dose annuelle en fonction de l'origine (interne ou externe) de ces rayonnements. La détermination de la dose annuelle nécessite la mesure des activités en radioéléments des différents échantillons et de leur environnement et une mesure de dosimétrie in situ par spectrométrie gamma ou pose de dosimètres TL.

<p>The technique of ESR-dosimetry and strategies for investigation of new materials as in regard to their applicability as ESR-dosimeters for radiotherapy has been reviewed. As an example six salts of formic and lactic acid has been evaluated. The applicability of the dosimeter has been judged by evaluating the tissue equivalence, radical yield, radical stability, spectral suitability, optimal readout parameters, dose response and sensitivity of the dosimetric system. Dependence of material characteristics and influence parameters has been analysed.</p><p>The reviewed methods have been successfully used for evaluation of the new materials. Lithium formate has been shown to be a good candidate relative to the state of the art dosimeter of alanine. Using optimal readout parameters lithium formate has been shown to be nine times as sensitive but even at moderate settings lithium formate is more sensitive. The results for lithium formate are in accordance to those of previous studies. The signal intensity of sodium formate has also proved to be high but unfortunately the signal fades rapidly.</p><p>Two new methods have been proposed as synthesis of the reviewed methods. The first allows flexible, effective and objective baseline correction of the ESR-spectrum. The second deals with dose response measurement by linear regression of the entire spectrum and was found to be successful in separating the spectral peaks of the induced radicals from the background signal.</p>

The technique of ESR-dosimetry and strategies for investigation of new materials as in regard to their applicability as ESR-dosimeters for radiotherapy has been reviewed. As an example six salts of formic and lactic acid has been evaluated. The applicability of the dosimeter has been judged by evaluating the tissue equivalence, radical yield, radical stability, spectral suitability, optimal readout parameters, dose response and sensitivity of the dosimetric system. Dependence of material characteristics and influence parameters has been analysed. The reviewed methods have been successfully used for evaluation of the new materials. Lithium formate has been shown to be a good candidate relative to the state of the art dosimeter of alanine. Using optimal readout parameters lithium formate has been shown to be nine times as sensitive but even at moderate settings lithium formate is more sensitive. The results for lithium formate are in accordance to those of previous studies. The signal intensity of sodium formate has also proved to be high but unfortunately the signal fades rapidly. Two new methods have been proposed as synthesis of the reviewed methods. The first allows flexible, effective and objective baseline correction of the ESR-spectrum. The second deals with dose response measurement by linear regression of the entire spectrum and was found to be successful in separating the spectral peaks of the induced radicals from the background signal.

No description available.

Neste trabalho foi desenvolvido um programa para simular espectros de ressonância paramagnética eletrônica (RPE) de onda contínua de amostras policristalinas para tensores não coincidentes. O Hamiltoniano de spin utilizado inclui os tensores anisotrópicos g, interação hiperfina, divisão de campo zero e quadrupolar e o termo Zeeman nuclear isotrópico. O programa inclui várias tecnologias novas, tais como: segmentação de campo com teoria de perturbação de autocampo para localizar as posições de campo ressonante, os métodos de distribuição Espiral e Repulsão para determinar o conjunto de orientações e a interpolação bidimensional triangular para reduzir o número de orientações computadas. A conjunção desses algoritmos podem aumentar a velocidade e a precisão das simulações, especialmente na simulação de espectros de sistemas de spin de dimensões grandes. O programa foi testado em algumas situações reais e o resultado obtido pode ser considerado, em alguns casos, equivalente aos programas comerciais e, em outros casos, de qualidade superior. / A computer program to simulate continuous wave electron paramagnetic resonance (EPR) powder spectra for noncoincident tensors has been developed. The spin Hamiltonian used includes anisotropic g, hyperfine interaction, zero field splitting and quadrupolar tensors and isotropic nuclear Zeeman term. The program includes a number of new technologies such as: field positions, spiral and repulsion methods for determining a set of orientations and triangular bidimensional interpolation to reduce the number of computed orientations. The conjunction of these algorithms can greatly increase the speed and the accuracy of simulations; especially in simulating powder spectra of spin systems of large dimensions. The program has been tested in some real situations and the obtained result can be considered, in some cases, equivalent to that of commercial software, in other cases, of superior quality.