The dissertation thesis is focused on research and development in the field of microfabrication by the technology of electron beam lithography. In the first part of this work, the extensive study is conducted in the field of technology of electron beam lithography in terms of physical principles, writing strategies and resist materials. This is followed with description of physical principles of etching for the transfer of relief structures into substrates. The thesis describes innovative techniques in modelling, simulation, data preparation and optimization of manufacturing technology. It brings new possibilities to record deep binary or multilevel microstructures using electron beam lithography, plasma and reactive ion etching technology. Experience and knowledge in the large area of microlithography, plasma and anisotropic wet-etching of silicon have been capitalized to the design process of manufacturing of nano-patterned membranes. It was followed with practical verification and optimization of the microfabrication process.

Gegenstand dieser Arbeit ist die Untersuchung der Ober?ächen- bzw. Grenz?ächenphotospannung (SPV) an dünnen organischen Schichten auf Metallsubstraten. Besonderes Augenmerk gilt dabei dem System dünner Schichten von 3,4,9,10-Perylen- Tetracarbonsäure-Di-Anhydrid (PTCDA) auf einem Au(110)-Kristall. Für diese Untersuchungen wurde eine phasensensitive Methode auf der Basis der Photoelektronenspektroskopie (PES) mit zusätzlicher modulierter Lichteinstrahlung entwickelt, die es erlaubt, lichtinduzierte Verschiebungen des Ober?ächenpotentials mit einer Au?ösung ? 1mV zu detektieren. Diese modulierte Photoelektronenspektroskopie wird ausführlich vorgestellt. Eine makroskopische Kelvin-Sonde und die Kelvin-Sonden-Rasterkraftmikroskopie (KPFM) werden als weitere Möglichkeiten zur Bestimmung des Ober?ächenpotentials vorgestellt. Die Photospannung wird mit diesen Methoden in Bezug auf drei Parameter untersucht: Da die Barriere an der Grenz?äche, welche für die Ausbildung der Photospannung ursächlich ist, durch die Photospannung reduziert wird, geben Messungen der SPV in Abhängigkeit von der eingestrahlten Lichtleistung Informationen über die energetische Struktur der Grenz?äche, speziell über die Höhe der Barriere. Mit den ebenfalls aus diesen Methoden gewonnen Informationen über die Austrittsarbeit und Ionisationsenergie von PTCDA lässt sich ein Bandschema des Systems Au/PTCDA entwickeln. Die wellenlängenabhängigen Messungen zeigen, dass Exzitonen in verschiedenen Zuständen erzeugt werden. Diese werden mit unterschiedlichen Photonenenergien angeregt und besitzen unterschiedliche Di?usionslängen. Da die Exzitonen zum Dissoziieren an die Grenz?äche di?undieren müssen, tragen die unterschiedlichen Exzitonenzust ände mit unterschiedlichem Anteil zur Photospannung bei. Die Untersuchungen der Entstehungs- und Zerfallszeit zeigen, dass sich die Photospannung sehr schnell nach Lichteinschaltung aufbaut. Der Abbau der Photospannung nach Lichtabschaltung erfolgt vergleichsweise langsam. Dies bedeutet, dass die Ladungsträger, die nach der Ladungsträgertrennung in der organischen Schicht zur ückbleiben, in Fallenzuständen gebunden sind, aus denen sie thermisch aktiviert werden müssen. In einem separaten Abschnitt werden die Entwicklung sowie Messergebnisse eines Stimmgabel-Rasterkraftmikroskops (AFM) vorgestellt. Dieses ermöglicht die hochau ?ösende topographische Abbildung der Ober?äche mit einer vertikalen Sensitivität im Ångström-Bereich. Das Ziel, mit diesem Gerät KPFM zu betreiben, konnte beim Einsatz an Luft nicht verwirklicht werden. / Subject of this work is the investigation of surface and interface photovoltage (SPV) of thin organic films on metal substrates. Special attention is focused on the system of thin layers of 3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA) on an Au(110) crystal. For this investigation a novel phase sensitive method was developed based on photoelectron spectroscopy (PES) under additional modulated illumination. It provides the possibility to detect light induced changes in the surface potential with a resolution of about 1mV. This modulated photoelectron spectroscopy is described in detail. Macroscopic Kelvin probe and Kelvin probe force microscopy (KPFM) are presented as further possibilities to measure the surface potential. The photovoltage is investigated by these techniques regarding three parameters: Due to the fact that the barrier at the interface is responsible for the formation of the photovoltage and that the height of this barrier is reduced by the photovoltage, the measurement of the dependence of the SPV on the intensity of the incident light provides information about the energetic structure of the interface. Together with the values of the work function and the ionisation energy of PTCDA, also gained with this methods, a band diagram of the interface can be developed. The wavelength dependent measurements show that excitons can be generated in multiple states. They are excited at different photon energies and have different diffusion lengths. The excitons have to diffuse to the interface to dissociate. Therefore the different excitation states contribute to SPV with different amounts. The investigations upon the generation and decay of the photovoltage shows that the SPV signal appears immediately after switching on the illumination. The decay of the photovoltage after switching off the light is much slower. This implies that the charge carriers are trapped as they remain in the organic film after charge separation at the interface. They have to be thermally activated from this traps. In an extra chapter the development and measurement results of a tuning fork scanning force microscope (AFM) are described. This AFM features high resolution topography images with a vertical sensitivity in the range of single angstroms.

In this work systematic studies of the organic semiconductor CuPc have been presented. In general the investigation can be devided in three parts. In the first one we have studied the electronic structure of clean CuPc thin film. The next two parts are devoted to organic-organic and metal–organic interface formation, where one of the interface components is CuPc thin film. The main results of this thesis are: - The electronic structure of the pristine organic semiconductor CuPc (valence band and empty states) has been obtained by a combination of conventional and resonant photoemission, near-edge X-ray absorption, as well as by theoretical ab initio quantum-chemical calculations. A qualitative assignment of different VB structures has been given, or in other words the contributions of different atomic species as well as sites of the CuPc molecule to the electronic DOS has been established. In particular, it was shown, that the HOMO is mainly comprised of the spectral weights from the orbitals of carbon pyrolle atoms. Additional contributions to the HOMO stems from the benzene atoms. A combined experimental and theoretical study of the unoccupied electronic density of states of CuPc was presented. Our study allows identifying the contributions from different parts of the molecule to the unoccupied DOS and the measured spectra, which lays grounds for future studies of the evolution of the CuPc electronic states upon e.g. functionalization or doping. Application of similar studies to other organic semiconductors will also provide significant insight into their unoccupied electronic states. - The electronic properties of the organic heterointerfaces between fullerite and pristine copper phthalocyanine were studied. Both interfaces, CuPc/C60 and C60/CuPc, were found to be non-reactive with pronounced shifts of the vacuum level pointing to the formation of an interfacial dipole mainly at the CuPc side of the heterojunctions. The dipole values are close to the difference of the work functions of the two materials. Important interface parameters and hole-injection barriers were obtained. The sequence of deposition does not influence the electronic properties of the interfaces. - CuPc doped with potassium was studied by means of photoemission and photoabsorption spectroscopy. A detailed analysis of the core-level PE spectra allows one to propose possible lattice sites, which harbor the potassium ions. Contrasting to a few results reported in the literature, the films prepared in this thesis showed no finite electronic density of states at the Fermi level. - Two stages of the In/CuPc interface formation have been distinguished. The low-coverage stage is characterized by a strong diffusion of the In atoms into the organic film. Metal ions occupy sites close to the pyrolle nitrogen and strongly interact with molecules transferring negative charge to CuPc. Indium diffusion into the organic films saturates at a stoichiometry of In2CuPc. Subsequently, in the second stage the formation of a metallic indium film occurs on the top of the In2CuPc film. - Upon deposition on CuPc film Sn and Ag atoms do not diffuse into the organic film forming metallic clusters and/or thin metallic overlayer. Sharp metal-organic film interface is formed, in contrast to indium and potassium deposition. Presented experimental results also give evidence for absence of noticeable chemical reaction of Sn and Ag with CuPc thin film. - The systematic investigation of interface formation between CuPc thin film and various metals gives us the possibility to summarize all results with demonstrating similarities and differences for all systems studied.

Cette recherche part du constat d'un dysfonctionnement de l'aide au développement et à la conservation. Depuis les années 1980 et malgré la succession des stratégies de l'aide, les résultats restent souvent insatisfaisants, médiocres, voire contraires aux effets recherchés. Pour comprendre ce phénomène, nous partons d'un territoire forestier, Amindrabe, situé au Centre-Est de Madagascar. En nous focalisant sur ce territoire, ses habitants et les programmes d'aide qui le ciblent, nous prenons progressivement conscience des logiques sous-jacentes à ce système global du développement : qu'est-ce qui s'y passe concrètement ? Comment est-ce organisé ? Pourquoi ces dynamiques se poursuivent-elles malgré des effets décevants ? La singularité de notre proposition est de nous détacher de la littérature surplombante pour partir du perçu et du vécu des habitants et des porteurs des programmes. Cette analyse empirique et qualitative amène à poser un regard critique sur les croyances fondatrices des stratégies de l'aide. Nous mettons en lumière une organisation hiérarchisée et compartimentée en différentes sphères déconnectées entre elles et déconnectées de la réalité locale. Les croyances, illusions et intérêts de chacun participent à renforcer l'incompréhension entre sphères et à détourner les actions des objectifs initiaux, par un processus qui se répète. En décortiquant un système d'acteur particulier, ses mondes et ses dynamiques du local au global, nous invitons le lecteur à un plongeon au-delà de ces incompréhensions. / This research is based on the observation of a dysfunction in aid for development and conservation. Since the 1980s and despite the succession of aid strategies, the results are often unsatisfactory, mediocre or even contrary to the desired effects. To understand this phenomenon, we begin in a forest territory, Amindrabe, located in the Central-East of Madagascar. By focusing on this territory, its inhabitants and the aid programs that target it, we gradually become aware of the underlying logic of this global development system: what is actually happening there? How is it organized? Why do these dynamics go on despite disappointing effects? The singularity of our proposal is to detach ourselves from the overhanging literature to start with the perceived experiences of the inhabitants and the bearers of the programs. This empirical and qualitative analysis leads us to take a critical look at the founding beliefs of aid strategies. We highlight a hierarchical and compartmentalized organization in different spheres: disconnected from each other and disconnected from the local reality. The beliefs, illusions and interests of each actor contribute to reinforce the incomprehension between spheres and to divert the actions from the initial objectives by a process that repeats itself. By anatomizing a particular actor system, its worlds and its dynamics from local to global, we invite the reader to a dive beyond these incomprehensions.

Made available in DSpace on 2016-04-28T19:59:13Z (GMT). No. of bitstreams: 1 Carlos Eduardo Siqueira Ferreira de Souza.pdf: 1642585 bytes, checksum: 913d09f1c598648bdb032fedee52c11e (MD5) Previous issue date: 2008-10-22 / The main objective of this research is to examine, in the writings of Ana Cristina Cesar, the relationships between the texture of her autobiographical discourse and the cinematic editing method, with particular attention to the texts comprised in A teus pés, published in 1982. Such objective was chosen in view of the fact that Ana Cristina Cesar s poetic work reveals composition methods of a singular late 20th century lyrical voice, marked by a fragmentary language, analogous with the cinematic technique of frames juxtaposition and the procedures that account for autobiographical and confessional texts. In order to understand how this woman poet appropriates an autobiographical discourse and transforms it, and whether the cinematic language takes part in the autobiographical construction process of Ana Cristina s poetry through the organization of fragments in the text, we start from the following hypotheses: autobiographism is a lyrical and fictional method in Ana Cristina s fragmentary poetry; cinematic editing provides solutions to the contiguity of analogical images in her poetic writing; fragmentarism is the procedure that brings together the cinematic and the autobiographical discourse. Such hypotheses were tested in the light of: Bakhtin s reflections in Aesthetics of Verbal Creation, which deal with confessional and autobiographical genres; the concept of biographeme as proposed by Roland Barthes; and the cinematic editing studies carried out by theoreticians and scholars such as Sergei Eisenstein, Ismail Xavier, Peter Burger and Modesto Carone Netto. We conclude that Ana Cristina Cesar brings together the depragmatizing, self-reflexive tendency of modern art and the disillusioned, faithless attitude of our contemporary age, by deconstructing in her writings the concepts of identity and authorship, in an attempt to depersonalize the self. In the texts written by this woman poet from Rio de Janeiro, the biographeme is apprehended as a fragmentary and non-linear composition method which, together with the frames juxtaposition procedure that constitutes cinematic editing, results in a unique relationship between reality and fiction, achieved by means of an erotic texture in which a reality that emerges and disappears from the text is displayed. Bringing forth a dramatic interplay in which the poetic persona takes to the stage and displays its multiplicity to the reader, Ana Cristina Cesar s writing reveals that the theatralization of the self on the textual stage is an alternative to the invention of a creative and liberating identity / O principal objetivo desta pesquisa é examinar, na escritura de Ana Cristina Cesar, em especial nos textos que compõem A teus pés, editado em 1982, as relações entre a tessitura do discurso autobiográfico e o método de montagem cinematográfica. Tal objetivo foi traçado, considerando-se que a obra poética de Ana Cristina Cesar revela, como métodos de composição de uma voz lírica singular do final do século XX, a linguagem fragmentária, análoga à técnica cinematográfica de justaposição de planos, e os procedimentos constituintes de textos autobiográficos e confessionais. A fim de compreendermos como a poeta se apropria do discurso autobiográfico, transformando-o, e se a linguagem cinematográfica participa, por meio da organização de fragmentos no texto, do processo de construção do autobiografismo na poesia de Ana C., partimos das seguintes hipóteses: o autobiografismo é um método lírico ficcional na poesia fragmentada de Ana Cristina Cesar; a montagem cinematográfica fornece soluções para a contigüidade das imagens analógicas na escritura poética; o fragmentarismo é um procedimento que alia os discursos cinematográfico e autobiográfico. Tais hipóteses foram testadas à luz: das reflexões elaboradas por Bakhtin, em Estética da criação verbal, sobre os gêneros confessionais e a autobiografia; do conceito de biografema proposto por Roland Barthes; e de estudos sobre a montagem cinematográfica, realizados por teóricos e estudiosos como Sergei Eisenstein, Ismail Xavier, Peter Bürger e Modesto Carone Netto. Concluímos que Ana Cristina Cesar alia a tendência despragmatizante e auto-reflexiva da arte moderna à postura descrente e desiludida da contemporaneidade, desconstruindo, em sua escritura, as noções de identidade e de autoria, numa tentativa de despersonalização do sujeito. Nos textos da poeta carioca, o biografema é apreendido como um método de composição fragmentada e alinear, que, aliado ao procedimento de justaposição de planos que constitui a montagem cinematográfica, constrói uma relação singular entre real e ficção mediante uma tessitura erótica, na qual se estabelece a encenação de uma realidade que aparece e desaparece do texto. Instauradora de um jogo dramático em que o sujeito poético encena sua multiplicidade para o leitor, a escritura de Ana Cristina Cesar revela que a teatralização do eu no palco textual é uma alternativa para a invenção de uma identidade criativa e libertadora

Submitted by Rosina Valeria Lanzellotti Mattiussi Teixeira (rosina.teixeira@unisantos.br) on 2016-05-18T18:07:21Z No. of bitstreams: 1 Adelmar Azevedo Regis.pdf: 1651570 bytes, checksum: fea6985b4a975695e6c1917ebcb65ca8 (MD5) / Made available in DSpace on 2016-05-18T18:07:23Z (GMT). No. of bitstreams: 1 Adelmar Azevedo Regis.pdf: 1651570 bytes, checksum: fea6985b4a975695e6c1917ebcb65ca8 (MD5) Previous issue date: 2015-11-05 / This work analyzes the Payment for Environmental Services (PES) as a promising economic instrument to solve some problems related to environmental degradation and the generation of positive externalities. To achieve such goal, firstly the thesis analyzes concepts of externality and public goods and the main existing theories to tackle market failures, citing three specific environmental principles to combat negative and positive externalities: Polluter-Pays Principle, User-Pays Principle and Principle Protector-Receiver, which is the modern promotional function of law. Then, the thesis conducts a comparative analysis between the command and control instruments and economic instruments and their efficaciousness and cost-effectiveness in environmental preservation. With such a basis built, this work then defines environmental services and their types and promotes a literature review on the theoretical aspects that support PES schemes, as well as addresses two foreign case studies of PSA and some experiences in Brazil. This paper contributes to the theoretical development of the subject, still little explored in literature, and intends to demonstrate that the payment of environmental services is not a magical solution to the environmental crisis and did not appear to replace command and control instruments; it has to be added to current instruments of environmental policy, in order to correct market failures, which do not recognize the inherent value of ecosystem services and the benefits they provide to social welfare. / O trabalho analisa os Pagamentos por Serviços Ambientais (PSA) como um instrumento econômico promissor para resolver alguns problemas relacionados à degradação ambiental e à geração de externalidades positivas. Para tanto, parte primeiramente de uma análise dos conceitos de externalidade e de bens públicos e das principais teorias existentes para combater as falhas de mercado, mencionando os três princípios ambientais específicos para combater as externalidades negativas e positivas: Princípio do Poluidor-Pagador, Princípio do Usuário-Pagador e Princípio do Protetor-Recebedor, que representa a moderna função promocional do Direito. Em seguida, promove uma análise comparativa entre os instrumentos de comando e controle e os instrumentos econômicos e sua eficácia e custo-benefício na preservação ambiental. Construída essa base, definem-se, então, os serviços ambientais e seus tipos, e se realiza revisão da literatura sobre os aspectos teóricos que dão suporte aos esquemas de PSA, inclusive abordando dois casos de sucesso de PSA no exterior e algumas experiências no Brasil. O presente trabalho contribui para o desenvolvimento teórico da temática, ainda pouco explorada na literatura, e tem por escopo demonstrar que o pagamento de serviços ambientais não é uma solução mágica para a crise ambiental e não surgiu para substituir instrumentos de comando e controle, mas para se somar aos atuais instrumentos de política ambiental, com a função de corrigir as falhas do mercado, que não reconhece o valor intrínseco dos serviços ecossistêmicos e os benefícios que eles proporcionam ao bem-estar da sociedade.

Core- and Valence Photoelectron Spectroscopy (PES), X-ray- and Ultraviolet-Visible Absorption Spectroscopy (XAS and UV-Vis), Scanning Tunneling Microscopy (STM) and Density Functional Theory (DFT) calculations are used to study the electronic and geometrical structure of a class of macro-cyclic molecules, Phthalocyanines (Pc), on surfaces. These molecules are widely studied due to their application in many different fields. Multilayer and monolayer coverages of Iron Phthalocyanine (FePc) and metal-free Phthalocyanine (H2Pc) deposited on different surfaces are investigated in order to get insight in the electronic and geometrical structure of the obtained overlayers, of crucial importance for the understanding of the film functionality. Sublimation of molecular thick films on Si(100) and on conducting glass results in films with molecules mainly oriented with their molecular plane orthogonal to the surface. Ex-situ deposited H2Pc films on conductive glass show different molecular orientation and morphology with respect to the vacuum sublimated films. We study the monolayer adsorption structure of FePc and H2Pc and compare our results with other Pc’s adsorbed on graphite. We find that the molecular unit cell and the superstructure is characteristic for each Pc adsorbed on graphite, even if the geometrical size of the compared molecules is the same. The PE- and XA- spectra of FePc on graphite are essentially identical for the mono- and multilayer preparations, evidencing weak intermolecular and molecular-substrate interactions of van der Waals nature. Furthermore, we characterize Pc’s on InSb (001)-c(8x2). The substrate In rows are observed to be the adsorption site for Pc’s. We find that the growth of the two-dimensional islands of FePc is prolonged in the [-110] direction, in contrast to ZnPc adsorbed on the same substrate at room temperature. We interpret this result as an indication that the adsorption is controlled by the substrate corrugation observed at 70 K.

In the present work a Metal / organic / inorganic semiconductor hybrid heterostructure (Ag / DiMe−PTCDI / GaAs) was built under UHV conditions and characterised in situ. The aim was to investigate the influence of the organic layer in the surface properties of GaAs(100) and in the electrical response of organic−modified Ag / GaAs Schottky diodes. The device was tested by combining surface−sensitive techniques (Photoemission spectroscopy and NEXAFS) with electrical measurements (current−voltage, capacitance−voltage, impedance and charge transient spectroscopies). Core level examination by PES confirms removal of native oxide layers on sulphur passivated (S−GaAs) and hydrogen plasma treated GaAs(100) (H+GaAs) surfaces. Additional deposition of ultrathin layers of DiMe−PTCDI may lead to a reduction of the surface defects density and thereby to an improvement of the electronic properties of GaAs. The energy level alignment through the heterostructure was deduced by combining UPS and I−V measurements. This allows fitting of the I−V characteristics with electron as majority carriers injected over a barrier by thermionic emission as a primary event. For thin organic layers (below 8 nm thickness) several techniques (UPS, I−V, C−V, QTS and AFM) show non homogeneous layer growth, leading to formation of voids. The coverage of the H+GaAs substrate as a function of the nominal thickness of DiMe−PTCDI was assessed via C−V measurements assuming a voltage independent capacitance of the organic layer. The frequency response of the device was evaluated through C−V and impedance measurements in the range 1 kHz−1 MHz. The almost independent behaviour of the capacitance in the measured frequency range confirmed the assumption of a near geometrical capacitor, which was used for modelling the impedance with an equivalent circuit of seven components. From there it was found a predominance of the space charge region impedance, so that A.C. conduction can only takes place through the parallel conductance, with a significant contribution of the back contact. Additionally a non linear behaviour of the organic layer resistance probably due to the presence of traps was deduced. ( ) ω ' R QTS measurements performed on the heterostructure showed the presence of two relaxations induced by deposition of the organic layer. The first one is attributed to the presence of a deep trap probably located at the metal / organic interface, while the second one has very small activation energy ( ~ 20 meV) which are probably due to disorder at the organic film. Those processes with small activation energies proved to be determinant for fitting the I−V characteristics of DiMe−PTCDI organic modified diodes using the expressions of a trapped charge limited current regime TCLC. Such a model was the best analytical approach found for fitting the I−V response. Further improving probably will involve implementation of numerical calculations or additional considerations in the physics of the device.

Photoelectron spectroscopy is an experimental method to study the electronic structure in matter. In this thesis, a combination of soft and hard X-ray based photoelectron spectroscopy has been used to obtain atomic level understanding of electronic structures and energy level alignments in mesoscopic solar cells. The thesis describes how the method can be varied between being surface and bulk sensitive and how to follow the structure linked to particular elements. The results were discussed with respect to the material function in mesoscopic solar cell configurations. The heart of a solar cell is the charge separation of photoexcited electrons and holes, and in a mesoscopic solar cell, this occurs at interfaces between different materials. Understanding the energy level alignment between the materials is important for developing the function of the device. In this work, it is shown that photoelectron spectroscopy can be used to experimentally follow the energy level alignment at interfaces such as TiO2/metal sulfide/polymer, as well as TiO2/perovskite. The electronic structures of two perovskite materials, CH3NH3PbI3 and CH3NH3PbBr3 were characterized by photoelectron spectroscopy and the results were discussed with support from quantum chemical calculations. The outermost levels consisted mainly of lead and halide orbitals and due to a relatively higher cross section for heavier elements, hard X-ray excitation was shown useful to study the position as well as the orbital character of the valence band edge. Modifications of the energy level positions can be followed by core level shifts. Such studies showed that a commonly used additive in mesoscopic solar cells, Li-TFSI, affected molecular hole conductors in the same way as a p-dopant. A more controlled doping can also be achieved by redox active dopants such as Co(+III) complexes and can be studied quantitatively with photoelectron spectroscopy methods. Hard X-rays allow studies of hidden interfaces, which were used to follow the oxidation of Ti in stacks of thin films for conducting glass. By the use of soft X-rays, the interface structure and bonding of dye molecules to mesoporous TiO2 or ZnO could be studied in detail. A combination of the two methods can be used to obtain a depth profiling of the sample.

Made available in DSpace on 2016-06-02T19:33:09Z (GMT). No. of bitstreams: 1 KAWAICHI_Vanessa_2012.pdf: 2539108 bytes, checksum: a9216ce702fc0aba843b8b6a772550de (MD5) Previous issue date: 2012-03-30 / The present study aims to estimate the supply of environmental services Sorocaba Rivers Basin and Middle Tietê, located in the central-southeastern state of Sao Paulo. The focus of the environmental service is given to the hydrological services, which are responsible for providing farmers in the region. Thus, from the provision of environmental services in the Basin, we estimated the value of PES to farmers based on the opportunity cost of changing agricultural practices on farms in the region. The methodology is based on the opportunity cost of changing a conventional practice for a conservation practice. The opportunity cost was obtained from the comparison between the yield of each crop analyzed by adopting the conventional practice and practice conservation. Thus, we analyzed the yields of major crops Basin (coffee, corn, beans, potatoes, sugar cane, orange, tomato, onion, grapes, rice and cassava), comparing the difference between the yields for both practices. The classification for conservation practice and conventional practice followed at the discretion of the forest area of the basin, considering the municipalities with an area of forest above average as conservation and below average, as conventional. Thus, the forest area was used as a proxy for measuring the environmental service in question, knowing that the preservation of vegetation provides a number of benefits, including conservation of water resources. The results show that the estimated values of PES for the main crops of the Basin can range from R$100/ha/year to R$30.000/ha/year. In relation to the cultures analyzed in this study, we can say that with the highest potential for implementation of programs for PES were the crops of rice and cassava, which, besides having more profitable return for the conservation practice, have a initial offering of high environmental services and the lowest values for PES. Cultures orange, tomato, onions and grape also have an initial supply of high environmental services, however, PES values are estimated quite high in comparison with other cultures, thereby implementing programs to increase the supply PES environmental services in this case should consider how much the payment would compensate for the provision of environmental services provided by these cultures. / O presente trabalho tem como objetivo estimar a oferta dos serviços ambientais na Bacia Hidrográfica dos Rios Sorocaba e Médio Tietê, localizada na região centrosudeste do Estado de São Paulo. O enfoque de serviço ambiental é dado aos serviços hidrológicos, cujos responsáveis pela oferta são os produtores rurais da região. Assim, a partir da oferta de serviços ambientais da Bacia, estimou-se o valor do PSA aos produtores rurais baseado no custo de oportunidade da mudança de práticas agrícolas nas propriedades rurais da região. A metodologia adotada é baseada no custo de oportunidade da mudança de uma prática convencional para uma prática conservacionista. O custo de oportunidade foi obtido a partir da comparação entre o rendimento de cada cultura analisada, adotando-se a prática que gera menos serviços ambientais e e a prática que gera mais serviços ambientais. Dessa forma, foram analisados os rendimentos das principais culturas da Bacia (café, milho, feijão, batata, cana, laranja, tomate, cebola, uva, arroz e mandioca), comparando-se a diferença entre os rendimentos para ambas as práticas. A classificação das práticas obedeceu ao critério de área de mata da Bacia, considerando-se os municípios com área de mata acima da média como B e, abaixo da média, como A. Dessa forma, a área de mata foi utilizada como proxy para a mensuração do serviço ambiental em questão, sabendo-se que a preservação da cobertura vegetal proporciona uma série de benefícios, inclusive, a conservação dos recursos hidrológicos. Os resultados mostram que os valores estimados do PSA para as principais culturas da Bacia podem variar de R$100/ha/ano a R$30.000/ha/ano. Em relação às culturas analisadas neste estudo, pode-se dizer que as que apresentaram maior potencial para a implementação de programas de PSA foram as culturas do arroz e da mandioca, as quais, além de apresentarem retorno mais rentável para a prática conservacionista, apresentam uma oferta inicial de serviços ambientais elevada e os menores valores para o PSA. As culturas laranja, tomate, cebola e uva também apresentam uma oferta inicial de serviços ambientais elevada, no entanto, os valores de PSA estimados são bem elevados em comparação com as demais culturas, dessa forma, a implementação de programas de PSA para aumentar a oferta de serviços ambientais neste caso deve considerar o quanto o pagamento compensaria a oferta de serviços ambientais proporcionados por essas culturas.