Dissertations / Theses on the topic 'Pump-probe'
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Costa, Felicissimo Viviane. "Infrared - X-ray pump probe spectroscopy." Licentiate thesis, Stockholm : Theoretical Chemistry, Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-324.
Full textSpencer, Ben. "Pump-probe spectroscopy of photovoltaic materials." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/pumpprobe-spectroscopy-of-photovoltaic-materials(f4b7f755-338a-4fad-814c-4dcc95d5b72d).html.
Full textCosta, Felicissimo Viviane. "Principles of Infrared - X-ray Pump-probe Spectroscopy." Doctoral thesis, KTH, School of Biotechnology (BIO), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4245.
Full textThe present thesis concerns theoretical studies of molecular interactions investigated by infrared and X-ray spectroscopic techniques, with emphasis on using these two techniques combined in pump-probe experiments. Four main types of studies are addressed: the use of near-edge X-ray absorption fine structure spectra (NEXAFS) to manifest through-bond and through-space interactions; the role of hydrogen bonding in the formation of X-ray photoelectron spectra as evidenced by simulations of the water dimer; the development of theory, with sample applications, for infrared X-ray pump-probe spectroscopy; and molecular dynamics simulations of light-induced fragmentation of water clusters.
Ab initio calculations indicate that NEXAFS spectra give direct information about the through-bond and through-space interactions between vacant non-conjugated π* orbitals. It is found out that the X-ray photoelectron spectrum of the water dimer differs dramatically from the monomer spectrum in that two bands are observed, separated by the chemically shifted ionization potentials of the donor and the acceptor. The hydrogen bond is responsible for the anomalously strong broadening of these two bands. The studies show that X-ray core electron ionization of the water dimer driven by an infrared field is a proper technique to prove the proton transfered state contrary to conventional X-ray photoelectron spectroscopy.
The physical aspects of the proposed new X-ray spectroscopic method - phase sensitive Infrared - X-Ray Pump-Probe Spectroscopy - are examined in detail using the wave packet technique in three applications; the NO molecule and the dynamics of proton transfer in core ionized water dimer and glyoxalmonoxime. It is found out that the phase of the infrared pump field strongly influences the trajectory of the nuclear wave packet on the ground state potential, which results in a phase dependence of the X-ray pump-probe spectra. A proper choice of the delay time of the X-ray pulse allows the direct observation of the X-ray transition in the proton transfered well of the core excited potential. It is found out that the glyoxalmonoxime molecule possesses an important feature; proton transfer accompanied by core hole hopping. Special attention is paid to the quantum control of the populations of vibrational level which is of crucial importance to shape the wave packet of desirable size.
The wave packet technique becomes computationally very expensive when the number of nuclear degrees of freedom is large. Molecular dynamics is used instead in studies of light-induced nuclear kinetics in the water hexamer cluster. We predict a novel mechanism of the mechanical action of light on atoms and molecules. This mechanism is based on the rectification of the Lorentz force, which gives a unique opportunity of direct site selective mechanical action of light on atoms and molecules inside large systems like clusters or biomolecules.
Costa, Felicíssimo Viviane. "Principles of infrared - x-ray pump-probe spectroscopy /." Stockholm : Royal Insitute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4245.
Full textReinertsen, Johannes F. "Simulation of Ultrafast Pump-Probe Measurements for Semiconductors." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19336.
Full textFLE, Guillaume. "Extending the pump energy range for a pump-probe system using High Harmonics Generation." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-266350.
Full textDominguez, Pablo Nahuel. "Pump-probe measurements of reaction centers from Rhodobacter sphaeroides." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-185735.
Full textLakehal, Massil. "Out of Equilibrium Lattice Dynamics in Pump Probe Setups." Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7039.
Full textThe study of the out of equilibrium dynamics of strongly correlated systems, using ultrafast pulses, uncovered a plethora of phenomena with no analog in equilibrium physics. In this thesis, we theoretically investigate the out of equilibrium dynamics of the lattice degrees of freedom and their signature in pump-probe spectroscopy. We develop a Hamiltonian-based microscopic description of laser pump induced displacive coherent phonons. The theory captures the feedback of the phonon excitation upon the electronic fluid, which is missing in the state-of-the-art phenomenological formulation. We show that this feedback leads to chirping at short timescales, even if the phonon motion is harmonic. At long times, this feedback appears as a finite phase in the oscillatory signal. We apply the theory to BaFe2As2, explain the origin of the phase in the oscillatory signal reported in recent experiments, and we predict that the system will exhibit redshifted chirping at larger fluence. Our theory also opens the possibility to extract equilibrium information from coherent phonon dynamics. Another interesting phenomenon that have been reported in pump-probe spectroscopy is the oscillation of the lattice fluctuations at double phonon frequency. These oscillations are invariably interpreted as a signature of macroscopic squeezed phonon states. In this work, we identify other mechanisms of double phonon frequency oscillations that do not involve squeezing. We show that a pump induced temperature quench of the bath, to which the phonon is coupled to, or exciting a coherent phonon for which cubic anharmonicity is allowed by symmetry can also produce such oscillations in noise spectroscopy without squeezing the phonon state. We conclude that, in contrast with what is commonly believed, double phonon frequency oscillations in noise spectroscopy are not necessarily a signature of macroscopic phonon squeezing. We point out what can be a reliable criterion to identify a squeezed phonon using pump-probe spectroscopy
Walke, Daniel John. "New instrumentation and methods for ultrafast pump-probe spectroscopy." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/48040.
Full textHenriksen, Lisa Grav. "Pump-probe experiments of multicrystalline silicon for solar cell applications." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19207.
Full textEhrler, Oli T. "Ultraschnelle zeitaufgelöste Pump-Probe-Photoelektronenspektroskopie an isolierten und massenselektierten Anionen." Karlsruhe : Univ.-Verl. Karlsruhe, 2006. http://www.uvka.de/univerlag/volltexte/2006/181/.
Full textWu, Jing. "Optical pump-probe studies of spin dynamics in ferromagnetic materials." Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364427.
Full textMatía, Hernando Paloma. "Attosecond pump-probe methods for measurement of molecular hole dynamics." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/50155.
Full textFabris, Davide. "Ultrafast light sources and methods for attosecond pump-probe experiments." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/25283.
Full textOmbinda-Lemboumba, Saturnin. "Femtosecond pump probe spectroscopy of light harvesting complexes and Phthalocyanines." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17894.
Full textENGLISH ABSTRACT: The generation of ultrafast light pulses and the development of time resolved spectroscopic techniques, such as the femtosecond pump probe spectroscopy technique, have facilitated the study of ultrafast energy transfer in the photosynthetic systems of green plants and photodynamic therapy drugs. It has allowed the investigation of biological and chemical processes that take place on the ultrafast timescale and has allowed us to obtain spectral and kinetic information on energy transfer. In addition, it has allowed time resolved experiments in which the transient absorption of species under investigation was observed and has elucidated molecular dynamics. In the present work this was done with a temporal resolution of approximately 200 fs and covering a pump-to-probe delay range of 300 fs to 2 ns. The main aims of this study were to characterise the femtosecond pump probe spectroscopy system, to investigate the energy transfer in the natural light harvesting complex II (LHC II) in view of future expansion to the study of synthesized arti cial functional light harvesting complexes and nally to study ultrafast processes in zinc phthalocyanine (ZnPc) systems. In photosynthetic organisms, LHC II is the most abundant light harvesting complex and it plays an important role in light harvesting and photoprotection. The light energy is absorbed by light harvesting complexes and transferred to a reaction centre (RC) in an ultrafast timescale. Phthalocyanines are a new class of photosensitiser used for photodynamic therapy. These drugs are used to treat small and super cial tumours. The energy transfer from the singlet excited state to the triplet excited state occurs on an ultrafast timescale. However, recent work done on zinc phthalocyanine has proved that the determination of the ultrafast component remains a challenge. Several ultrafast studies carried out on ZnPc in solvents have been not only unsuccessful to give a clear picture of the ultrafast dynamics but have also produced divergent results. In this study, a characterisation of the femtosecond pump probe spectroscopy setup was done. The samples under investigation were probed by a white light continuum. The generation of the white light continuum introduced chirp, which in uenced the temporal evolution of the transient absorption results. The technique used to correct the chirp introduced by white light generation is discussed in detail. Our femtosecond pump probe spectroscopy setup was benchmarked by using a well known dye, namely malachite green. In addition, the investigation of the transient absorption change of LHC II, an active component in photosynthesis, as extracted from spinach leaves and the ultrafast dynamics of a promising photosensitiser ZnPc in dimethyl sulfoxide (DMSO) as well as in dimethyl formamide (DMF) was done. The spectral and dynamic results obtained using these three samples are described and exponential ts to the absorbance decay curves used to estimate the timescales of the energy transfer processes are presented. In this experiment, the dynamics and measured time constants related to the energy transfer between the different types of chlorophyll in LHC II was monitored, whereas with ZnPc, the dynamics and the measured time constants associated with solvation dynamics and vibrational relaxation was examined.
AFRIKAANSE OPSOMMING: Die vorming van ultravinnige lig pulse en die ontwikkeling van tyd opgelosde spektroskopiese tegnieke, soos die femtosekonde pomp proef spektroskopie tegniek, het die studie van ultravinnige energie oordrag in fotosintetiese stelsels van groen plante en chemiese prosesse gefasiliteer, wat kan plaasvind op die ultravinnige tyd skaal en laat dit toe om spektrale en kinetiese informasie oor die energie oordrag te kan bepaal. Dit het ook dit moontlik gemaak om tyd opgelosde eksperimente te kan doen waarin ons veranderlike absorbsie van die monster kon ondersoek en die molekulere dinamika kon ontrafel. In hierdie werk is dit gedoen met n tyd resolusie van omtrent 200 fs termyl 'n pomp-tot-proef tydvertraging van 300 fs tot 2 ns gebruik is. Die hoof doelwitte van hierdie werk was om 'n femtosekonde pomp proef spektroskopie stelsel te karakteriseer, die energie oordrag in die natuurlike ligoes kompleks II te ondersoek met die toekomstige uitbreiding van die studie na sintetiese lig-oes komplekse as oogmerk en laastens om ultravinnige prosesse in Sink Ftalosianiene stelsels te ondersoek. In fotosintetiese organismes, is lig oes kompleks II die mees volop lig oes kompleks en speel 'n belangrike rol in lig oes en foto skerming. Die lig energie word geabsorbeer deur lig oes komplekse en dan oorgedra na reaksie middelpunte in 'n ultravinnige tydskaal. Ftalosianiene is 'n nuwe klas fotosensiteerder wat gebruik word in fotodinamiese terapie. Hierdie dwelms word gebruik om klein en oppervlakkige gewasse te behandel. Die energie oordrag van die opgewekte singlet tot die triplet toestand vind plaas op die ultravinnige tydskaal. Onlangse navorsingswerke het getoon dat die bepaling van die ultravinnige komponent 'n uitdaging bly. Verskeie vorige ondersoeke is gedoen op Sink Ftalosianiene in verskeie oplosmiddels, en nie net het hierdie studies nie 'n helder prentjie verskaf van die ultravinnige dinamika nie, maar het ook divergerende resultate opgelewer. In hierdie werk word 'n karakterisering van die femtosekonde pomp proef spektroskopie stelsel gedoen. Die monsters is ondersoek met 'n wit lig kontinuum proef. Die vorming van die wit lig kontinuum het tjirp veroorsaak, wat die tyd evolusie van die veranderlike absorbsie resultate beinvloed het. Die tegniek wat gebruik was om die tjirp te korregeer word bespreek. Ons femtosekonde pomp proef spektroskopie stelsel is gestandardiseer deur die welbekende kleurstof malachiet groen. Ons het ook die veranderlike absorbsie van lig oes kompleks II ondersoek, 'n aktiewe komponent in fotosintese, soos dit onttrek is uit spinasie blare, asook die ultravinnige dinamika van die belowende photosensitizer Sink Ftalosianiene in DMSO asook DMF. Die spektrale en dinamiese resultate verkry vanaf hierdie drie monsters word beskryf en eksponensiele passings aan die absorbsie verval kurwes is gebruik om die tydskale van die energie oordrag prosesse te skat. In hierdie eksperiment is dinamika en gemete tydkonstantes waargeneem wat toegeskryf kan word aan die energie oordrag tussen verskillende soorte chloro l in lig oes kompleks II. In die Sink Ftalosianien eksperimente is dinamika en gemete tydkonstantes waargeneem wat toegeskryf kan word aan solverings dinamika asook vibrasionele ontspanning.
Cheng, Yu-Hsiang. "Photoinduced dynamics studied by ultrafast single-shot pump-probe spectroscopy." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122684.
Full textThesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 155-168).
This thesis focuses on the development of dual-echelon single-shot spectroscopy and its applications to study irreversible photoinduced dynamics. First, the ultrafast laser sources and the related control and characterization techniques are discussed. In particular, we have invented a two-stage dual-beam noncollinear optical parametric amplifier to provide tunable sources for pump-probe spectroscopy. Next, the experimental setup of dual-echelon single-shot spectroscopy is illustrated with great detail and possible noise sources and correction methods are explored. Using the single- shot technique, we studied photoinduced dynamics in three different materials. In bismuth, we found a transition into a transient symmetric phase at high fluences. We showed the coherent control of phonon parameters with pump-pump-probe experiments. We also simulated the carrier and phonon dynamics using a modified two-temperature model. In tellurium, we demonstrated that the amorphization of crystalline tellurium induced by femtosecond pulses is a thermal process. We also estimated the lattice temperature by the change in phonon frequency. In a strained manganite film, we observed a photoinduced persistent insulator-to-metal transition and showed the partial recovery of the generated metallic phase to the insulating phase.
by Yu-Hsiang Cheng.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
Harper, Matthew R. "Control and measurement of ultrafast pulses for pump/probe-based metrology." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/430.
Full textIssenmann, Daniel [Verfasser]. "Studium der Phononendynamik mit Pump-Probe-Experimenten im Röntgenbereich / Daniel Issenmann." Konstanz : Bibliothek der Universität Konstanz, 2014. http://d-nb.info/1050348818/34.
Full textChung, Dutch D. 1969. "Femtosecond pump-probe spectroscopy of chemical reactions in liquids and crystals." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/10022.
Full textBacon, David Robert. "Time-resolved pump-probe investigation of the terahertz quantum cascade laser." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17968/.
Full textLozan, Olga. "Surface plasmons and hot electrons imaging with femtosecond pump-probe thermoreflectance." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0021/document.
Full textIn this work we explored the ultrafast dynamics of photo-excited hot electrons in plasmonic structures. The particular interest of this field resides on the fact surface plasmons (SP), because of their unrivaled temporal and spatial characteristics, provide a technological route for ultrafast information processes at the nanoscale. In this context, this manuscript provides a comprehension and the harnessing of one of the major limitation of the SP-based technologies : absorption losses by Joule heating. We exploit the fact that the mechanism of plasmon absorption in metals is followed by generation of hot electrons at femtosecond time scale, thus losses can be seen as a plasmon-to-hot-electron energy conversion. This energy conversion is measured with femtosecond pump-probe technique. Femtosecond SP pulses are launched and probed over hundred femtoseconds through the permittivity variations induced by the hot-electron gas and which accompany the SP propagation. The measured electron temperature profile is therefore an image of plasmon power density distribution (absorption) not broadened spatially and temporally by energy carrier diffusion. As an important result we demonstrated the capability to link the electronic temperature measurement to the plasmonic absorption, revealing an anomalous light absorption for a sub- slit surroundings, in quantitative agreement with predictions of the power density distribution. In a second part we studied plasmon losses and their characteristics when they propagate on semi-infinite metal film. We determined the electronic thermal wave velocity and damping. In the last part we used a focusing taper-structure to adiabatically guide and focus the plasmon at the apex. Was demonstrated the generation of a nanoscale hot spot and put in evidence a delayed electron heating at the taper apex. Perspectives and the remaining open questions are also discussed
Kim, Yang-Hyo. "Wide-field structured illumination microscopy for fluorescence and pump-probe imaging." Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/121846.
Full textCataloged from PDF version of thesis.
Includes bibliographical references.
The optical resolution of microscopy is limited by the wave-like characteristic of the light. There are many recent advances in overcoming this diffraction limited resolution, but mostly focused on fluorescent imaging. Furthermore, there are few non-fluorescence wide-field super-resolution techniques that can fully utilize the applicable laser power to optimize imaging speed. Structured illumination microscopy is a super-resolution method that relies on patterned excitation. This thesis has presented novel applications of structured illumination microscopy to surface plasmon resonance fluorescence and pump-probe scattering imaging. First, structured illumination microscopy was introduced to surface plasmon resonance fluorescence imaging for high signal-to-noise and high resolution. Secondly, a theoretical framework for three-dimensional wide-field pump-probe structured illumination microscopy has been developed to increase the lateral resolution and enable depth sectioning. Further, structured illumination wide-field photothermal digital phase microscopy is proposed as a high throughput, high sensitivity super-resolution imaging tool to diagnose ovarian cancer. Finally, I have derived the exact analytical solution to the heat conduction problem in which a sphere absorbs temporally modulated laser beam for photothermal microscopy. The proposed method also has a great potential to be applied to other pump-probe modalities such as transient absorption and stimulated Raman scattering.
Funding sources and sponsors: National Institutes of Health (9P41EB015871-26A1, 5R01NS051320, 4R44EB012415, and 1R01HL121386-OlAl), National Science Foundation (CBET-09395 11), Hamamatsu Corporation, Singapore-Massachusetts Institute of Technology Alliance for Research and Technology (SMART) Center, BioSystems and Micromechanics (BioSyM), and Samsung Scholarship
by Yang-Hyo Kim.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering
Wald, Hagen. "Ultrafast carrier dynamics investigated by a novel pump and probe terahertz technique." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=971803943.
Full textFlögel, Martin [Verfasser]. "Raising the XUV Intensity towards Attosecond-Attosecond Pump-Probe Experiments / Martin Flögel." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1133492347/34.
Full textGriessel, Annelle. "The investigation of resveratrol with conventional and ultrafast pump-probe spectroscopy techniques." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/3098.
Full textAn ultrafast pump-probe spectroscopy experiment was developed in order to investigate the fast photoinduced isomerization reaction of the molecule resveratrol. Characteristics of the resveratrol molecule are discussed, including the photoisomerization reaction from trans- to cis-resveratrol. The experimental setup for the conventional spectroscopy measurement was developed and characterized in order to investigate and understand the conventional absorption and uorescence spectroscopy of resveratrol thoroughly. The absorption spectra for both trans- and cis-resveratrol, as well as the uorescence spectra were measured, discussed and explained. This therefore forms a foundation and serves as an initial step to develop a pump-probe spectroscopy experiment for resveratrol. A general overview of ultrafast pump-probe spectroscopy is presented, as well as an explanation of the nal developed experimental setup. The principles and characteristics of the chirped pulse ampli cation (CPA) femtosecond laser source and the tunable noncollinear optical parametric ampli er (NOPA) employed as the pump pulse are discussed. The process of white light continuum (WLC) generation was investigated to utilize as the ultrashort probe pulse. Two white light continuum generation experimental setups were developed and characterized for WLC generation in a transparent medium with the fundamental CPA laser light at 775 nm (in sapphire) and with the second harmonic (SH) of the CPA light at 387 nm (in quartz). A spectrometer was designed, built and characterized in conjuction with a line focus, for simultaneous measurement of the absorption in the pumped, unpumped and reference regions in the sample. In this way the photoisomerization of resveratrol could be measured with temporal resolution as a transient absorption signal. A 420 μg/ml resveratrol solution in ethanol was investigated in this pump-probe spectroscopy experiment and the results obtained are discussed accordingly.
Souther, Nathan Jon. "Light Shift Measurements of Cold Rubidium Atoms using Raman Pump-Probe Spectroscopy." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1250622906.
Full textCavanagh, Molly Christine. "Using the ultrafast pump-probe spectroscopy of atomic anions and the solvated electron to probe solvent structure and solvation dynamics." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1581642021&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full textKruglyak, Volodymyr. "Femtosecond optical pump-probe investigations of ultrafast electron and spin dynamics in metals." Thesis, University of Exeter, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410811.
Full textNyamuda, Gibson Peter. "Optical second harmonic generation and pump-probe reflectivity measurements from Si/SiO2 interfaces." Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5317.
Full textENGLISH ABSTRACT: Silicon/silicon dioxide (Si/SiO2) interface is widely used in microelectronics as the gate between the drain and source of most metal oxide semiconductor field effect transistors (MOSFETs). The functionality, reliability and electrical properties of such transistors are strongly dependent on the quality of the Si/SiO2 structure forming the gate. Characterization of the Si/SiO2 interface is important in understanding device degradation therefore the Si/SiO2 interface is a subject of intensive investigation. Research studies of Si/SiO2 interfaces using optical methods have been reported by many groups around the world but to date many open questions still exist. The physics of photoinduced trap or defect generation processes and the subsequent trapping of charge carriers, the precise role of photoinduced interfacial electric field in altering optical properties of the Si/SiO2 interface and its role in affecting the second harmonic (SH) yield measurements are not well understood. In this work a commercial near infrared femtosecond (fs) laser source [1.55 eV, 75 ± 5 fs, 10 nJ, 80 MHz] is used to study native Si/SiO2 interfaces of free standing single crystalline Si membrane and bulk Si. Optical second harmonic (SH) generated at the Si/SiO2 interfaces of a Si membrane in reflection and for the first time in transmission is demonstrated as well as stationary, single colour, pump-probe reflectivity measurements from the Si/SiO2 interface of bulk n-type Si. The experimental setups for the second harmonic generation (SHG) and pump-probe techniques were designed and implemented, and measurements were recorded by a computer controlled data acquisition system. Free standing Si membrane samples were successfully produced at the Institut f¨ur Photonische Technologien (IPHT) in Jena, Germany from bulk Si using a chemical etching process and were characterised using the z-scan technique. The penetration depth of light with a photon energy of 1.55 eV in silicon allows transmission of the fundamental fs laser pulses through the Si membrane (∼ 10 μm in thickness) and this is exploited to generate a SH signal in transmission from the Si/SiO2 interfaces of the Si membrane. In the presence of sufficiently intense fs laser light defects are created at the interfaces and populated by multiphoton transfer of charges from Si to SiO2 where they are subsequently trapped. The transfer of charge establishes interfacial electric fields across the interfaces of the Si membrane and this enhances SHG. This phenomenon is called electric field induced second harmonic (EFISH) generation. To our knowledge, EFISH measurements from interfaces of Si membrane performed in transmission are demonstrated for the first time in the present study. The demonstration of EFISH in transmission revealed new results which allowed us to provide additional perspectives on the EFISH generation process at Si/SiO2 interfaces never reported before. The temporal response of SH signals from virgin spots were recorded at different incident laser powers for both reflection and transmission geometries. The SH responses measured in transmission were observed to be time dependent and show an increase during irradiation of the sample corresponding to EFISH process. A series of SH measurements were recorded at different laser powers to compare the magnitudes of SH yield in each detection geometry for a single Si/SiO2 interface. The magnitude of the SH yield measured in transmission was higher than expected and surpassed the SH yield measured in reflection. The expectation is based on the fact that the local intensity of the fundamental beam at the second interface where the SH in transmission is generated is low compared to the local intensity at the first interface where the SH in reflection originates. A physical model is developed to consistently interpret the experimental results obtained in this study. In this model we established the origin of EFISH signals in each detection geometry, explain the unexpected high SH signals measured in transmission and provide an analysis of the time constants extracted from SH response in transmission and reflection. In addition, we also report for the first time stationary pump-probe reflectivity measurements from bulk n-type Si(111) samples with native oxide. A strong pump beam was focused on the same spot as a weak probe beam from the same fs laser source. The change in reflectivity of the Si(111)/SiO2 system was recorded by monitoring the change in intensity of the weak reflected probe beam. The temporal evolutions of the reflectivity of the material were recorded at different pump powers. The reflectivity of the material increases over several minutes of irradiation and reaches steady-state after long time irradiation. The change in reflectivity of the material is attributed to a nonlinear process called Kerr effect, and the temporal response arises from the photoinduced interfacial electric field across the Si(111)/SiO2 interface caused by multiphoton charge transfer from bulk Si(111) to the SiO2 layer. The results reported in this study contribute to the understanding of the photoinduced interfacial electric field caused by charge carrier separation across buried solid-solid interfaces. They also reveal nonlinear optical processes such as the Kerr effect caused by charge dynamics across the interface in addition to the well known SHG process.
AFRIKAANSE OPSOMMING: Die silikon/silikon dioksied (Si/SiO2) skeidingsvlak word algemeen gebruik in mikro-elektronika as die hek tussen die put en die bron van die meeste metaaloksied halfgeleier veld-effek transistors (MOSFETs). Die werkverrigting, betroubaarheid en elektriese eienskappe van sulke transistors word grootliks bepaal deur die kwaliteit van die Si/SiO2 struktuur wat die hek vorm. Karakterisering van die Si/SiO2 skeidingsvlak is belangrik om die degradering van die transistor te verstaan en daarom is die Si/SiO2 skeidingsvlak die onderwerp van intensiewe ondersoek. Ondersoek van die Si/SiO2 skeidingsvlak deur van optiese metodes gebruik te maak is geraporteer deur verskeie internasionale groepe, maar daar bestaan tot vandag toe nog n groot aantal onbeantwoorde vrae. Die fisika van die fotogenduseerde generering van defekte en van posisies waarin ladings gevang kan word, asook die daaropvolgende vasvang van ladingsdraers, die presiese rol van die fotoge¨ınduseerde elektriese veld oor die skeidingsvlak in die verandering van die optiese eienskappe van die Si/SiO2 skeidingsvlak en die grootte van die tweede harmoniek (SH) sein word nog nie goed verstaan nie. In hierdie werk word n kommersile naby-infrarooi femtosekonde (fs) laserbron [1.55 eV, 75 ± 5 fs, 10 nJ, 80 MHz] gebruik om natuurlike Si/SiO2 skeidingsvlakke van vrystaande enkelkristallyne Si membrane en soliede Si te bestudeer. Optiese tweede harmoniek (SH) wat by die Si/SiO2 skeidingsvlakke van ’n Si membraan gegenereer word - in refleksie en vir die eerste keer in transmissie - is gedemonstreer, asook stasionˆere, een-golflengte pomp-toets refleksiemetings op die Si/SiO2 skeidingsvlak van soliede n-gedoteerde Si. Die eksperimentele opstellings vir die tweede harmoniek generering (SHG) en pomp-toets tegnieke is ontwerp en uitgevoer en metings is opgeneem deur ’n rekenaarbeheerde dataversamelingstelsel. Vrystaande Si membraan monsters is suksesvol by die Institut f¨ur Photonische Technologien (IPHT) in Jena, Duitsland vervaardig uit soliede Si deur ’n chemiese etsproses en is gekarakteriseer met behulp van die z-skanderingstegniek as deel van hierdie studie. Die diepte waartoe lig met ’n fotonenergie van 1.55 eV in silikon indring laat die transmissie van die fundamentele fs laserpulse deur die Si membraan (met ∼ 10 μm dikte) toe en dit word ontgin om ’n SH sein van die Si/SiO2 skeidingsvlakke van die Si membraan in transmissie te meet. In die teenwoordigheid van fs laserlig met voldoende intensiteit word defekte by die skeidingsvlakke geskep en bevolk deur meer-foton ladingsoordrag van die Si na die SiO2 waar die ladings daaropvolgens vasgevang word. Die oordrag van ladings skep elektriese velde oor die skeidingsvlakke van die Si membraan en dit versterk die SHG. Hierdie verskynsel word elektriese veld ge¨ınduseerde tweede harmoniek (EFISH) generering genoem. Sover ons kennis strek is die meting van EFISH seine van skeidingsvlakke van Si membrane in transmissie vir die eerste keer in hierdie studie gedemonstreer. Die demonstrasie van EFISH in transmissie het nuwe resultate opgelewer wat ons toegelaat het om bykomende perspektiewe op die EFISH genereringsproses by Si/SiO2 skeidingsvlakke te verskaf waaroor nog nooit vantevore verslag gedoen is nie. Die tydafhanklike gedrag van die SH seine van voorheen onbestraalde posisies is gemeet by verskillende drywings van die inkomende laserbundel vir beide die refleksie en transmissie geometrie¨e. Die gedrag van die SH sein in transmissie is waargeneem om tydafhanklik te wees en ’n toename te toon gedurende bestraling van die monster in ooreenstemming met EFISH prosesse. ’n Reeks van SH metings is opgeneem by verskillende laserdrywings om die groottes van die SH opbrengste in elke meetgeometrie vir ’n enkele Si/SiO2 skeidingsvlak te vergelyk. Die grootte van die SH opbrengs wat in transmissie gemeet is was ho¨er as verwag is en het die grootte van die SH opbrengs in refleksie oortref. Die verwagting is gebaseer op die feit dat die lokale intensiteit by die tweede skeidingsvlak waar SH in transmisie gegenereer word relatief laag is in vergelyking met die lokale intensiteit by die eerste skeidingsvlak waar SH in refleksie ontstaan. ’n Fisiese model is ontwikkel om die eksperimentele resultate wat in hierdie studie verkry is op ’n konsekwente wyse te interpreteer. In hierdie model het ons die oorsprong van EFISH seine in elke meetgeometrie vasgestel, die onverwagte ho¨e SH seine wat in transmissie gemeet is verklaar en ’n analise van die tydkonstantes wat uit die SH gedrag in transmissie en refleksie afgelei is gedoen. Verder rapporteer ons ook vir die eerste keer stasionˆere pomp-toets reflektiwiteitsmetings van soliede n-gedoteerde Si(111) monsters met ’n natuurlike oksied. ’n Sterk pompbundel is gefokus op dieselfde posisie as ’n swak toetsbundel van dieselfde laserbron. Die verandering in reflektiwiteit van die Si(111)/SiO2 stelsel is gemeet deur die verandering in die intensiteit van die swak weerkaatste toetsbundel te monitor. Die tydevolusie van die reflektiwiteit van die mate riaal is gemeet by verskillende pompdrywings. Die reflektiwiteit van die materiaal neem toe gedurende etlike minute van bestraling en bereik ’n stasionˆere toestand na ’n lang tyd van bestraling. Die verandering in reflektiwiteit van die materiaal word toegeskryf aan ’n nielini ˆere prosess, naamlik die Kerr effek, en die tydafhanklike gedrag ontstaan as gevolg van die fotoge¨ınduseerde elektriese veld oor die Si(111)/SiO2 skeidingsvlak wat veroorsaak word deur meer-foton ladingsoordrag van die soliede Si(111) na die SiO2 laag. Die resultate wat in hierdie studie gerapporteer word dra by tot die verstaan van die fotoge ¨ınduseerde elektriese veld oor die skeidingsvlak wat veroorsaak word deur die skeiding van ladingsdraers oor die bedekte kristal-kristal skeidingsvlak. Dit lˆe ook nie-liniˆere optiese prosesse soos die Kerr effek bloot wat veroorsaak word deur die dinamika van ladings oor die skeidingsvlak, bykomend tot die bekende SHG proses.
Jackson, Richard Aram Jr. "A Preliminary Study of Pump/Probe Angular Dependence of Zeeman Electromagnetically Induced Transparency." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1439372287.
Full textDe, Angelis Annalisa. "Electro-optical pump-probe system suitable for the investigation of electroporated biological cells." Limoges, 2012. http://aurore.unilim.fr/theses/nxfile/default/46acb249-db11-4e5f-a29e-8bfcec5a48f4/blobholder:0/2012LIMO4016.pdf.
Full textUn champ électrique suffisamment intense induit des effets sur la membrane cellulaire, notamment la formation des pores qui permettent le passage , autrement interdit, de ions et molécules, d’où le nom électroporation. Grâce à son application à la biotechnologie et à la médecine (électrochimiothérapie), l’électroporation représente un phénomène de grand intérêt. Récemment, des impulsions de l’ordre de la nanoseconde ont étés appliquées, montrant des effets sur les membranes intracellulaires. Les mécanismes qui sont à la base de l’électroporation ne sont pas encore complètement compris. D’une part, il n’y a pas en commerce de générateurs ultra-rapides et flexibles pour une stimulation électrique adaptée. D’autre part, la détection de phénomènes à l’échelle subcellulaire et de dynamiques temporelles rapides résulte très difficile. En ce contexte, nous avons conçu et réalisé un système électro-optique pompe-sonde. Il se compose d’un système optoélectronique dédié à la génération d’impulsions ultracourtes et de forte intensité, et d’une source pour l’imagerie optique non linéaire basée sur la microspectroscopie multiplex-CARS. Les deux sources sont déclenchées par le même laser fonctionnant en régime sub-nanoseconde. Ce régime temporel permet une synchronisation efficace des deux systèmes, mais il nécessite d’une étude approfondie des effets optiques non linéaires qui induisent l’élargissement spectral du faisceau, indispensable pour l’imagerie multiplex-CARS. Une caractérisation dans le temps et en fréquence a été menée afin de vérifier les performances du system entier et son emploi aux études de nano-électroporation
Ehrler, Oli T. [Verfasser]. "Ultraschnelle zeitaufgelöste Pump-Probe-Photoelektronenspektroskopie an isolierten und massenselektierten Anionen / von Oli T. Ehrler." Karlsruhe : Univ.-Verl. Karlsruhe, 2006. http://d-nb.info/982607962/34.
Full textNargelas, Saulius. "Investigation of carrier dynamics in InN, InGaN, and GaAsBi by optical pump-probe techniques." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20130227_085934-75237.
Full textDisertacija skirta nepusiausvirųjų krūvininkų dinamikos tyrimams InN, InGaN ir GaAsBi heterosandarose naudojant šviesa indukuotų dinaminių gardelių ir skirtuminio pralaidumo metodikas. Atlikti tyrimai plačiame nepusiausvirųjų krūvininkų tankių ir bandinio temperatūrų intervale parodė, kad krūvininkų rekombinacijos sparta MBE būdu užaugintuose InN sluoksniuose dominuojantis rekombinacijos mechanizmas kambario temperatūroje yra gaudyklių įtakota Ožė rekombinacija. Nustatyta koreliacija tarp krūvininkų gyvavimo trukmės ir difuzijos koeficiento MOCVD būdu užaugintame InGaN sluoksnyje su 13% In parodė, kad krūvininkų gyvavimo trukmę lemia difuzinė jų perneša link rekobinacijos centrų. Parodoma, kad MBE metodu užaugintuose InGaN sluoksniuose su dideliu In kiekiu (x>0,7) didėjant Ga kiekiui didėja nespindulinės rekombinacijos centrų tankis, o krūvininkų rekombinacijos sparta yra termiškai aktyvuojama. MOCVD metodu užaugintose InGaN kvantinėse sandarose dinaminių gardelių tyrimais parodoma, kad spartėjančią krūvininkų rekombinaciją didėjant sužadinimo intensyvumui lemia ne tik spindulinė rekombinacija, tačiau reikia atsižvelgti ir į nespindulinės rekombinacijos spartėjimą. Nustatyta, kad į GaAs įterpiant Bi atomus daugiau nei dešimt kartų sumažėja skylių judris dėl Bi atomų kuriamų valentinės juostos fliuktuacijų.
Stensitzki, Till [Verfasser]. "Femtosecond Pump-Probe Spectroscopy on Corroles, Phytochromes, Channelrhodopsins and Ground-state Reactions / Till Stensitzki." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/120165484X/34.
Full textWilks, Ralph. "Measurements of linear and circular birefringence in metals by femtosecond optical pump-probe spectroscopy." Thesis, University of Exeter, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273027.
Full textCao, Wei. "Pump-probe study of atoms and small molecules with laser driven high order harmonics." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/18161.
Full textDepartment of Physics
Itzhak Ben-Itzhak and Charles Lewis Cocke
A commercially available modern laser can emit over 10^15 photons within a time window of a few tens of femtoseconds (10^-15 second), which can be focused into a spot size of about 10 um, resulting in a peak intensity above 10^14 W/cm^2. This paves the way for table-top strong field physics studies such as above threshold ionization (ATI), non-sequential double ionization (NSDI), high order harmonic generation (HHG), etc.. Among these strong laser-matter interactions, high order harmonic generation, which combines many photons of the fundamental laser field into a single photon, offers a unique way to generate light sources in the vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) region. High order harmonic photons are emitted within a short time window from a few tens of femtoseconds down to a few hundreds of attoseconds (10^-18 second). This highly coherent nature of HHG allows it to be synchronized with an infrared (IR) laser pulse, and the pump-probe technique can be adopted to study ultrafast dynamic processes in a quantum system. The major work of this thesis is to develop a table-top VUV(EUV) light source based on HHG, and use it to study dynamic processes in atoms and small molecules with the VUV(EUV)-pump IR-probe method. A Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) apparatus is used for momentum imaging of the interaction products. Two types of high harmonic pump pulses are generated and applied for pump-probe studies. The first one consists of several harmonics forming a short attosecond pulse train (APT) in the EUV regime (around 40 eV). We demonstrate that, (1) the auto-ionization process triggered by the EUV in cation carbon-monoxide and oxygen molecules can be modified by scanning the EUV-IR delay, (2) the phase information of quantum trajectories in bifurcated high harmonics can be extracted by performing an EUV-IR cross-correlation experiment, thus disclosing the macroscopic quantum control in HHG. The second type of high harmonic source implemented in this work is a single harmonic in the VUV regime (around 15 eV) filtered out from a monochromator. Experiments on D_2 molecules have been conducted using the 9th or the 11th harmonic as the pump pulse. Novel dissociative ionization pathways via highly excited states of D_2 have been revealed, thus suggesting potential applications for time-resolved studies and control of photochemistry processes.
Smith, Eric Ryan. "Femtosecond electronic realignment in a free base naphthalocyanine observed by pump-probe polarization anisotropy." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3303809.
Full textHayes, Sophia Charalambous. "Chlorine dioxide photochemistry in solution : time-resolved resonance Raman and femtosecond pump-probe studies /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/11614.
Full textLiu, Yingliang. "Structural Dynamics of DNA Hydration Shell Studied by 2D IR and Pump-Probe Technique." Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18559.
Full textBiochemical processes occur in an aqueous environment and interactions of the water shell with biomolecules play a key role for their structure and function. In this thesis, the structural dynamics of water molecules and counterions in the hydration shell of DNA is investigated by two-dimensional infrared (2D IR) spectroscopy and pump-probe transient spectroscopy. 2D IR spectroscopy is a powerful technique that can track molecular couplings between different vibrational modes and structural fluctuations of the chemical environment on a femto- to picosecond time scale. In the present study, vibrational modes of the DNA backbone serve as probes located at the DNA-water interface. The results of this thesis demonstrate the strong potential of interfacial vibrational modes for mapping and understanding interactions between biomolecules and their water shell. In future, this concept will be applied to other biomolecular systems.
Brands, Helge. "Ultrakurzzeitdynamik von Fulleriden in Lösung und suspendierten, längenselektierten Kohlenstoffnanoröhren." Karlsruhe Univ.-Verl. Karlsruhe, 2007. http://d-nb.info/989058131/04.
Full textWang, Qiang. "DNA photonics : probing photoinduced dynamics in DNA on the femtosecond time scale." Thesis, Boston College, 2008. http://hdl.handle.net/2345/33.
Full textThis dissertation introduces a new field of DNA photonics centering on the electronic properties of DNA, which emerges after the initial controversies regarding the long-range conductivity and wire-type behavior of DNA have been widely settled. DNA photonics study is not solely focused on charge transfer phenomena but encompasses all possible photophysical processes and their potentially complex interplays. For instance, ultrafast electronic energy migration, dissipation, and (de)localization on the femtosecond time scale are shown to be crucial for the description of light-induced dynamics in DNA and have been thoroughly investigated in this dissertation. In addition to measurements on natural single and double-stranded DNA, this dissertation also presents experimental data on a series of functionalized DNA systems (derivatized by stilbene, ethidium, 2-aminopurine, etc.), obtained by state-of-the-art femtosecond broadband pump–probe spectroscopy. The results illustrate the distance dependence of charge transfer, emphasize the role of the initial electronic excitation on energy transfer dynamics, and highlight the influence of structural factors on both processes in DNA. Finally, as one initial step towards DNA electronics application, a DNA mimicking system of tertiary arylureas were employed to demonstrate molecular wire behavior, implying its potential use in molecular electronics. Thus, both the experimental and theoretical research accumulated for DNA π–π coupling can be translated into designing and testing various molecular systems with similar π-stacked structures
Thesis (PhD) — Boston College, 2008
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
El-Khoury, Patrick Z. "Femtosecond Dynamics of Small Polyatomic Molecules in Solution: A Combined Experimental and Computational Approach." Bowling Green State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1272899005.
Full textWang, Yuda. "Optical Characterization of Mechanical and Electronic Properties of Visible to Infrared Semiconductor Nanowires." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1457426470.
Full textGolla, Dheeraj, Alexandra Brasington, Brian J. LeRoy, and Arvinder Sandhu. "Ultrafast relaxation of hot phonons in graphene-hBN heterostructures." AMER INST PHYSICS, 2017. http://hdl.handle.net/10150/624659.
Full textBellahn, Ute. "ps-UV-Pump-REMPI-Probe Spektroskopie an trans-Stilben Van-der-Waals-Clustern im Überschalldüsenstrahl." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962796735.
Full textKyriaki, Kosma. "UV-pump IR-probe Spectroscopy of Molecules with Time-Resolution reaching the 10-fs Range." Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-92803.
Full textMorrison, Vance. "Generation of tunable femtosecond laser pulses and the construction of an ultrafast pump-probe spectrometer." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116114.
Full textKarimi, Fawad [Verfasser]. "Towards Realtime Observation of Interatomic Coulombic Decay via XUV Pump - THz Probe Streaking / Fawad Karimi." München : Verlag Dr. Hut, 2019. http://d-nb.info/1190421941/34.
Full textMatthews, Thomas. "Pump-Probe Molecular Imaging." Diss., 2011. http://hdl.handle.net/10161/5685.
Full textIn this dissertation, we develop pump probe spectroscopy as a method to differentiate different chemical varieties of melanin, a common biopigment, and exploit these differences to improve the accuracy of melanoma diagnosis. This method gives insight into the chemical makeup and secondary structure of melanins. Pump probe spectroscopy is implemented in a scanning laser microscope as a form of multiphoton imaging, where it is used to image biopsies of human pigmented cutaneous lesions. Melanoma diagnosis is clinically challenging: the accuracy of visual inspection by dermatologists is highly variable and heavily weighted toward false positives. Even the current gold standard of biopsy results in varying diagnoses among pathologists. Using pump probe imaging, significant chemical and morphological changes were found between melanoma and melanocytic nevi, including increased eumelanin content, chemical heterogeneity and general pigmentation. Signal processing methods revealed further differences between melanoma and melanocytic nevi on the cellular scale. Pump probe imaging directly in H&E stained biopsy samples allows integration of this technique with existing histopathology protocols. High resolution imaging found chemical heterogeneity of melanin within pigmented cells. We show that oxyhemoglobin and deoxyhemoglobin may also be differentiated by pump probe imaging. Epi mode imaging of eumelanin, pheomelanin and microvasculature is demonstrated in vivo in human xenograft mouse models of melanoma.
Dissertation
Sheu, Fang-Wen, and 許芳文. "Study of Femtosecond Pump-Probe System." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/21266112027512978372.
Full text國立交通大學
電子物理學系
83
We have successfully built up a femtosecond pump-probe system to measure the relaxation behaviors of photoexcited carriers in both superconducting and semiconducting thin films. The laser source is a home-made passively mode-locked Ti: sapphire laser producing pulses with pulsewidth of about 150 fs and average power of about 400 mW. The output beam is guided into a home- made pump-probe system which can detect the change of reflectivity as small as 5*10^-5. Lock-in and differential detection techniques also have been used to obtain the measurement results with better signal to noise ratio. We have performed a series of femtosecond reflectivity measurements on both high Tc superconducting YBCO thin films with different oxygen contents and semiconducting GaAs thin films with different manufacturing processes and annealing conditions. We have found qualitatively different behaviors in the sign, magnitude and temporal response as various manufacturing processes of these thin films. Detailed explanation of the experimental results can be obtained by further improving the resolution of the pump-probe system and by measuring the electrical properties of these thin films.