Tesis sobre el tema "Molecular ionization"
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Yu, Youliang. "Computationally exploring ultrafast molecular ionization". Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38548.
Texto completoDepartment of Physics
Brett D. Esry
Strong-field ionization plays a central role in molecules interacting with an intense laser field since it is an essential step in high-order harmonic generation thus in attosecond pulse generation and serving as a probe for molecular dynamics through either the sensitivity of ionization to the internuclear separation or the laser-induced electron scattering. Strong-field molecular ionization has been studied both theoretically and experimentally, dominantly through the Born-Oppenheimer approximation and at equilibrium or small reaction distances. We have extended the theoretical studies of molecular ionization to a much broader extent. Specifically, due to the difficulty of treating ionization in Born-Oppenheimer representation especially for molecular dynamics involving strongly-correlated electron-nuclear motion, we have investigated an alternative time-independent--adiabatic hyperspherical--picture for a one-dimensional model of the hydrogen molecule. In the adiabatic hyperspherical representation, all the reaction channels--including ionization--for the hydrogen molecule have been identified in a single set of potential curves, showing the advantage of studying molecular dynamics involving multiple breakup channels coupled with each other. We have thus proposed a good candidate to study strongly-correlated molecular dynamics, such as autoionization and dissociative recombination. Moving to a time-dependent picture by numerically solving the time-dependent Schrödinger equation (TDSE), we have explored two extreme classes of strong-field ionization of hydrogen molecule ion: at large internuclear distances (R>30 a.u.) and for long-wavelength laser fields. Remarkably, we have found strong-field two-center effects in molecular ionization beyond the long-standing one-photon two-center interference as a manifestation of the double-slit interference. In particular, the total ionization probability at large internuclear distances shows strongly symmetry-dependent two-center dynamics in homonuclear diatomic molecules and two-center induced carrier-envelope phase effect in heteronuclear diatomic molecules. Such two-center effects are expected to generalize to other diatomic systems and could potentially be used to explain phenomena in multi-center strong-field physics. Moreover, we have theoretically confirmed, for the first time, the existence of low energy structure in molecular ionization in long-wavelength laser fields by solving the three-dimensional TDSE. Finally, we have performed a pump-probe study of the hydrogen molecular ion where a pump pulse first dissociates the molecule followed by a probe pulse which ionizes the dissociating wave packet, and surprisingly found a pronounced broad ionization peak at large R or large pump-probe delay (~150 fs). Numerically, we have developed and implemented new theoretical frameworks to more accurately and efficiently calculate quantum mechanical processes for small molecules--hydrogen molecule and its ion--which could readily be adapted to heavier diatomic systems.
Erbsen, Wes Corbin. "Non-dissociative single-electron ionization of diatomic molecules". Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/15740.
Texto completoDepartment of Physics
Carlos Trallero
Over the past four decades, the single-electron ionization of atoms has been a subject of great interest within the ultra-fast community. While contemporary atomic ionization models tend to agree well with experiment across a wide range of intensities (10[superscript]13-10[superscript]15 W/cm[superscript]2), analogous models for the ionization of molecules are currently lacking in accuracy. The deficiencies present in molecular ionization models constitute a formidable barrier for experimentalists, who wish to model the single-electron ionization dynamics of molecules in intense laser fields. The primary motivation for the work presented in this thesis is to provide a comprehensive data set which can be used to improve existing models for the strong-field ionization of molecules. Our approach is to simultaneously measure the singly-charged ion yield of a diatomic molecule paired with a noble gas atom, both having commensurate ionization potentials. These measurements are taken as a function of the laser intensity, typically spanning two orders of magnitude (10[superscript]13-10[superscript]15 W/cm[superscript]2). By taking the ratio of the molecular to atomic yields as a function of laser intensity, it is possible to "cancel out" systematic errors which are common to both species, e.g. from laser instability, or temperature fluctuations. This technique is very powerful in our ionization studies, as it alludes to the distinct mechanisms leading to the ionization of both molecular and atomic species at the same intensity which are not a function of the experimental conditions. By using the accurate treatments of atomic ionization in tandem with existing molecular ionization models as a benchmark, we can use our experimental ratios to modify existing molecular ionization theories. We hope that the data procured in this thesis will be used in the development of more accurate treatments describing the strong-field ionization of molecules.
Schug, Kevin Albert. "Pseudo-Molecular Ion Formation by Aromatic Acids in Negative Ionization Mode Electrospray Ionization Mass Spectrometry". Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29886.
Texto completoPh. D.
Gritschneder, Matthias. "Ionization and Triggered Star Formation in Turbulent Molecular Clouds". Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-104903.
Texto completoVanne, Yulian V. "Ionization of molecular hydrogen in ultrashort intense laser pulses". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16107.
Texto completoA novel ab initio numerical approach is developed and applied that solves the time-dependent Schrödinger equation describing two-electron diatomic molecules (e.g. molecular hydrogen) exposed to an intense ultrashort laser pulse. The method is based on the fixed-nuclei and the non-relativistic dipole approximations and aims to accurately describe both correlated electrons in full dimensionality. The method is applicable for a wide range of the laser pulse parameters and is able to describe both few-photon and many-photon single ionization processes, also in a non-perturbative regime. A key advantage of the method is its ability to treat the strong-field response of the molecules with arbitrary orientation of the molecular axis with respect to the linear-polarized laser field. Thus, this work reports on the first successful orientation-dependent analysis of the multiphoton ionization of H2 performed by means of a full-dimensional numerical treatment. Besides the investigation of few-photon regime, an extensive numerical study of the ionization by ultrashort frequency-doubled Ti:sapphire laser pulses (400 nm) is presented. Performing a series of calculations for different internuclear separations, the total ionization yields of H2 and D2 in their ground vibrational states are obtained for both parallel and perpendicular orientations. A series of calculations for 800nm laser pulses are used to test a popular simple interference model. Besides the discussion of the ab initio numerical method, this work considers different aspects related to the application of the strong-field approximation (SFA) for investigation of a strong-field response of an atomic and molecular system. Thus, a deep analysis of the gauge problem of SFA is performed and the quasistatic limit of the velocity-gauge SFA ionization rates is derived. The applications of the length gauge SFA are examined and a recently proposed generalized Keldysh theory is criticized.
McCartney, Mark. "Ionization processes in multielectron ion-atom collisions". Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359106.
Texto completoPurvis, John. "R-matrix-Floquet Theory of multiphoton ionization". Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239216.
Texto completoTrachy, Marc Lawrence. "Photoassociative ionization in cold rubidium". Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/695.
Texto completoUnderwood, Jonathan. "Vector properties in molecular photodissociation". Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311835.
Texto completoHayton, S. J. T. "Single and double ionization of ions by energy-resolved electrons". Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387406.
Texto completoCross, Gillian M. "The multiphoton multiple ionization of molecules in intense laser fields". Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283758.
Texto completoBlease, Trevor Graham. "Laser multiphoton ionization spectroscopy and analysis of the xylene isomers". Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/14139.
Texto completoGallimore, Peter James. "Molecular characterisation of organic aerosols using soft ionisation mass spectrometry". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709386.
Texto completoArnberg, Elise. "Investigation of molecular probes for pH determination with electrospray ionization mass spectrometry". Thesis, Uppsala universitet, Institutionen för kemi - BMC, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-381962.
Texto completoTremblin, Pascal. "Ionization impact on molecular clouds and star formation : numerical simulations and observations". Paris 7, 2012. http://www.theses.fr/2012PA077217.
Texto completoAt all the scales of Astrophysics, the impact of the ionization from massive stars is a crucial issue. What are the formation mechanisms of pillars and globules? Are the formation of the young stellar objects triggered or would have they formed anyway? Do massive stars have an impact on the distribution of the surrounding gas? Do they have an impact on the mass distribution of stars (the initial mass function, IMF)? This thesis aims at shedding some light on these questions, by focusing especially on the formation of the structures between the cold and the ionized gas. We present the state of the art of the theoretical and observational works on ionized regions (Hii regions) and we introduce the numerical tools that have been developed to model the ionization in the hydrodynamic simulations with turbulence performed with the HERACLES code. Thanks to the simulations, we present a new model for the formation of pillars based on the curvature and collapse of the dense shell on itself and a new model for the formations of cometary globules based on the turbulence of the cold gas. Several diagnostics have been developed to test these new models in the observations of RCW 120, RCW 36, Cygnus X, the Rosette and Eagle Nebulae thanks to Herschel column density maps and molecular-line data. We also present in appendix other works that have been done in parallel of this thesis: the charge exchange in colliding planetary and stellar winds and the sub-millimeter site testing at the Concordia station in Antarctica
Lindsay, Bernard Gregory. "State selected studies of some charge transfer and dissociative ionization collisions". Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317102.
Texto completoPaquette, Jay Paul. "The effect of realistic focal conditions on strong -field double ionization". W&M ScholarWorks, 2009. https://scholarworks.wm.edu/etd/1539623545.
Texto completoMagrakvelidze, Maia. "Nuclear dynamics and ionization of diatomic molecules in intense laser fields". Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2283.
Texto completoCameron, Brett Russell. "Investigations of the flow dynamics of supersonic molecular beams and the ionization of molecular clusters by electron impact". Thesis, University of Canterbury. Chemistry, 1993. http://hdl.handle.net/10092/8506.
Texto completoWatson, R. Craig Jr. "Laser-Ionization Time-of-Flight Mass Spectrometry of High Molecular Mass Inorganic Complexes". Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/35554.
Texto completo
This thesis describes the characterization of a LI-TOF-MS instrument and confirmation of theoretical time-of-flight mass-separation principles. Several test cases demonstrate the instrument's proper operation and calibration for a wide mass range of analytes. Mass spectral results of three organometallic compounds: i. [Ir(dpp)2Cl2](PF6), ii. {[(bpy)2Ru(dpp)]2IrCl2}(PF6)5, and iii. {[(bpy)2Ru(dpp)]2RuCl2}(PF6)5 under a variety of laser ionization and sample preparation conditions are compared. A complete structural characterization of the monometallic complex, [Ir(dpp)2Cl2](PF6), is presented. The two trimetallic analytes fragmented easily, but significant components of the molecules are successfully identified. After optimizing the ionization and analytical procedure, LI-TOF-MS proved useful in the analysis of high molecular mass metal complexes.
Master of Science
Thomason, J. W. G. "Direct and indirect ionization of Zn'+ and Mg'+ by energy-resolved electrons". Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316232.
Texto completoDashtiev, Maxim. "Fluorescence spectroscopy of trapped molecular ions produced with matrix-assisted laser desorption/ionization /". Zürich : ETH, 2006. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16949.
Texto completoFinch, Jeffrey William. "Selective mass spectrometry by single-photon ionization from a molecular hydrogen laser source". Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185895.
Texto completoHussien, Abdou Mekky Mousa. "Ionization of diatomic molecules in intense laser fields". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17323.
Texto completoThe ionization of some diatomic molecules, H2, N2, and O2, exposed to intense laser fields has been studied by comparing various molecular tunneling–ionization models with each other and with the numerical solution of the time-dependent Schrödinger equation (TDSE). The internuclear-distance dependent ionization yields over a wide range of laser peak intensities are investigated and the validity of the modified atomic and molecular tunneling models is examined. It is found that those models that depend on the quasi-static approximation, where ionization is independent on the oscillation frequency of the applied laser field, are useful for laser-induced ionization processes in only a very small region of the frequency and intensity domain of laser fields, i.e. in the tunneling regime. The models that include a frequency dependent factor are in a good agreement with the accurate TDSE calculations in both the multiphoton and the tunneling ionization regimes. Furthermore, the deviation from Franck-Condon-like distribution is also clarified. A small effect on the revival time of the vibrational wavepacket of hydrogen molecular ion, due to this deviation, has been found. Consideration of the bond-softening effect leads to a decrease in the revival time with increasing laser-peak intensity. The anisotropy of H2 as a function of laser intensity in linear and circular polarized fields using molecular tunneling model (MO-ADK) are also studied and a good agreement with the experimental observations, especially if the focal volume of the laser field is considered, has been obtained. The applicability of the two-center model for larger molecules, N2 and O2, is tested. It is found that it works with N2 (symmetric HOMO) but fails in O2 (ansymmetric HOMO).
Attah, Isaac Kwame. "BINDING ENERGIES AND SOLVATION OF ORGANIC MOLECULAR IONS, REACTIONS OF TRANSITION METAL IONS WITH, AND PLASMA DISCHARGE IONIZATION OF MOLECULAR CLUSTERS". VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/525.
Texto completoGaire, Bishwanath. "Imaging of slow dissociation of the laser induced fragmentation of molecular ions". Diss., Kansas State University, 2011. http://hdl.handle.net/2097/8852.
Texto completoDepartment of Physics
Itzhak Ben-Itzhak
Lasers are being used widely for the study and manipulation of the dynamics of atomic and molecular targets, and advances in laser technology makes it possible to explore new areas of research — for example attosecond physics. In order to probe the fragmentation dynamics of molecular ions, we have developed a coincidence three-dimensional momentum imaging method that allows the kinematically complete study of all fragments except electrons. Recent upgrades to this method allow the measurement of slow dissociation fragments, down to nearly zero velocity, in intense ultrafast laser fields. Evidences for the low energy breakup are presented using the benchmark molecules diatomic H[subscript]2[superscript]+ and polyatomic H[subscript]3[superscript]+ . The low energy fragments in H[subscript]2[superscript]+ dissociation are due to the intriguing zero-photon dissociation phenomenon. This first experimental evidence for the zero-photon dissociation is further supported by sophisticated theoretical treatment. We have explored the laser pulse length, intensity, wavelength, and chirp dependence of zero-photon dissociation of H[subscript]2[superscript]+, and the results are well described by a two-photon process based on stimulated Raman scattering. Similar studies of the slow dissociation of H[subscript]3[superscript]+ reveal that two-body dissociation is dominant over three-body dissociation. The most likely pathways leading to low-energy breakup into H[superscript]++H[subscript]2, in contradiction to the assessments of the channels in at least one previous study, are explored by varying the laser pulse duration and the wavelength. In addition, we have investigated the dissociation and single ionization of N[subscript]2[superscript]+ , and an interesting high energy feature in addition to the low energy has been observed at higher intensities. Such high energy results from the breakup of molecules in excited states are accessible at higher intensities where their potential energy is changing rapidly with the internuclear distance. We have extended the intense field ionization studies to other molecular ions N[subscript]2[superscript]+ , CO[superscript]+, NO[superscript]+, and O[subscript]2[superscript]+ . The dissociative ionization of these molecules follow a general mechanism, a stairstep ionization mechanism. Utilizing the capability of the upgraded experimental method we have measured the non-dissociative and dissociative ionization of CO[superscript]+ using different pulse lengths. The results suggest that dissociative ionization can be manipulated by suppressing some ionization paths.
Du, Meng Li. "The effect of closed classical orbits on quantum spectra: Ionization of atoms in a magnetic field". W&M ScholarWorks, 1987. https://scholarworks.wm.edu/etd/1539623773.
Texto completoMakhija, Varun. "Laser-induced rotational dynamics as a route to molecular frame measurements". Diss., Kansas State University, 2014. http://hdl.handle.net/2097/18522.
Texto completoDepartment of Physics
Vinod Kumarappan
In general, molecules in the gas phase are free to rotate, and measurements made on such samples are averaged over a randomly oriented distribution of molecules. Any orientation dependent information is lost in such measurements. The goal of the work presented here is to a) mitigate or completely do away with orientational averaging, and b) make fully resolved orientation dependent measurements. In pursuance of similar goals, over the past 50 years chemists and physicists have developed techniques to align molecules, or to measure their orientation and tag other quantities of interest with the orientation. We focus on laser induced alignment of asymmetric top molecules. The first major contribution of our work is the development of an effective method to align all molecular axes under field-free conditions. The method employs a sequence of nonresonant, impulsive laser pulses with varied ellipticities. The efficacy of the method is first demonstrated by solution of the time dependent Schr\"{o}dinger equation for iodobenzene, and then experimentally implemented to three dimensionally align 3,5 difluoroiodobenzene. Measurement from molecules aligned in this manner greatly reduces orientational averaging. The technique was developed via a thorough understanding and extensive computations of the dynamics of rotationally excited asymmetric top molecules. The second, and perhaps more important, contribution of our work is the development of a new measurement technique to extract the complete orientation dependence of a variety of molecular processes initiated by ultrashort laser pulses. The technique involves pump-probe measurements of the process of interest from a rotational wavepacket generated by impulsive excitation of asymmetric top molecules. We apply it to make the first measurement of the single ionization probability of an asymmetric top molecule in a strong field as a function of all relevant alignment angles. The measurement and associated calculations help identify the orbital from which the electron is ionized. We expect that this technique will be widely applicable to ultrafast-laser driven processes in molecules and provide unique insight into molecular physics and chemistry.
Johansson, Henrik. "Fragmentation of Amino Acids and Microsolvated Peptides and Nucleotides using Electrospray Ionization Tandem Mass Spectrometry". Licentiate thesis, Stockholms universitet, Fysikum, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-37202.
Texto completoAtkins, Danielle S. y N/A. "Electron Coincidence Studies of Molecules". Griffith University. School of Biomolecular and Physical Sciences, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070920.112918.
Texto completoAtkins, Danielle S. "Electron Coincidence Studies of Molecules". Thesis, Griffith University, 2007. http://hdl.handle.net/10072/367729.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Faculty of Science, Environment, Engineering and Technology
Full Text
Vajdi, Aram. "Experimental study of strong field ionization and high harmonic generation in molecules". Kansas State University, 2015. http://hdl.handle.net/2097/19161.
Texto completoPhysics
Vinod Kumarappan
This report includes the experimental details and results of two experiments. The first experiment addresses carrier envelope phase (CEP) effects in higher order harmonic generation (HHG), and the second experiment is a pump-probe experiment on CO₂ molecules using ultrashort laser pulses. Ultrashort laser pulses that are only a few optical cycles long are of interest for studying different atomic and molecular processes. The CEP of such a pulse is an important parameter that can affect the experimental results. Because the laser pulses we used in the HHG experiment have random CEP, we tagged a given harmonic spectrum with the CEP of the fundamental laser pulse that generated it by measuring both shot-by-shot. The first chapter of this report is about the experimental details and the results we got from our CEP-tagged HHG experiment that enabled us to observe the interference of different quantum pathways. In the second experiment, discussed in the second chapter of this report, we tried to study the structure of the CO₂⁺ ion created by strong field ionization in a pump-probe experiment. For this experiment, we used an ultrashort laser pulse to ionize CO₂ molecules, and after various time delays we probed the ionic wave packet by ionizing CO₂⁺ with another ultrashort laser pulse. By performing Fourier analysis on the delay-dependent CO₂⁺⁺ yield, we were able to identify the populated states of CO₂⁺.
Shi, Fengjian. "LASER ELECTROSPRAY MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATION FOR DIRECT ANALYSIS AND MOLECULAR IMAGING OF BIOLOGICAL TISSUE". Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/445496.
Texto completoPh.D.
This dissertation elucidates the instrumentation and application of a hybrid ambient ionization source, laser electrospray mass spectrometry (LEMS), for the direct analysis and molecular imaging of biological tissue without matrix deposition. In LEMS, laser pulses from a Ti:Sapphire laser amplifier (60 fs, 800 nm, and 1 mJ) interact with surface analytes and transfer them from the condensed phase into the gas phase without the requirement of either exogenous matrix or endogenous water in the sample. The laser vaporized analytes are captured and ionized by an electrospray source, and finally detected by a mass analyzer. It was found that a turn-key, robust femtosecond fiber laser with longer wavelength, longer duration, and lower pulse energy at 1042 nm, 425 fs, and 50 µJ, respectively, provided comparable results with the Ti:Sapphire laser. Vaporization of intact, dried or aqueous cytochrome c and lysozyme samples was demonstrated by the fiber laser. A charge states distribution at lower charge states indicating folded conformation of proteins and the hemoglobin α subunit-heme complex from whole blood was observed. Endogenous anthocyanins, sugars, and other metabolites were detected and revealed the anticipated metabolite profile for the flower petal and leaf samples by the fiber laser. Phospholipids, especially phosphatidylcholine, were identified from a fresh mouse brain section sample. These lipid features were suppressed in both the fiber laser and Ti:Sapphire LEMS measurement in the presence of optimal cutting temperature compounds which are commonly used in animal tissue cryosectioning. This dissertation also details the design of an automated mass spectrometry imaging source based on the Ti:Sapphire LEMS. The laser, translation stage, and mass analyzer are synchronized and controlled using a customized user interface to enable step-by-step scanning of the area of interest on a given tissue sample. The imaging source is coupled with a high resolution accurate mass quadrupole time-of-flight (QTOF) mass analyzer with tandem mass analysis capability. A lateral resolution of 60 µm was demonstrated on a patterned ink film by LEMS imaging. Plant metabolites including sugar and anthocyanins were directly imaged from a leaf sample. Small metabolites, lipids and proteins were simultaneously imaged from a single tissue section of a pig liver sample. Biomarkers of blood-brain barrier damage and traumatic brain injury (TBI) that occurred during the injury were detected and imaged from a TBI mouse brain. The loading values from principal component analysis (PCA) were shown to be useful for identification of features of interest from the large LEMS imaging dataset.
Temple University--Theses
Herrwerth, Oliver. "Atomic and molecular ionization dynamics in strong IR and XUV fields probed by time-resolved coincidence spectroscopy". Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-137966.
Texto completoKiontke, Andreas, Ariana Oliveira-Birkmeier, Andreas Opitz y Claudia Birkemeyer. "Electrospray ionization efficiency is dependent on different molecular descriptors with respect to solvent pH and instrumental configuration". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-216278.
Texto completoBohinski, Timothy Blaise. "STRONG FIELD MOLECULAR IONIZATION: CONTROLLED DISSOCIATION IN RADICAL CATIONS WITH DYNAMIC RESONANCES AND ADIABATICALLY PREPARED LAUNCH STATES". Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/310686.
Texto completoPh.D.
This dissertation investigates the electronic spectroscopy of a series of alkyl phenyl ketone radical cations and the dynamics of selective launch states in the strong field regime with tunable near infrared ultrashort laser pulses from 790 nm - 1550 nm coupled to mass spectrometric detection. Our method relies on tunable strong field laser pulses in the range from 1150 nm - 1550 nm to adiabatically ioinized gas phase molecules and prepare ions in the ground ionic state that serve as a launch state for future excitation and control. Adiabatic ionization is capable of transferring little energy to the molecule and producing a majority of a parent molecular ion in comparison to nonadiabatic ionization wherein multiple ionic states can be populated with an accompanying high degree of molecular fragmentation. We measure a dynamic resonance in the low lying electronic states of the acetopheone radical cation via preparation of a launch state with adiabatic ionization followed by a one photon transition within a single pulse duration which facilitates bond dissociation to produce the benzoyl ion. Experiments on acetophenone homologues and derivatives elucidate the structural dependence of the electronic resonance and supporting ab initio calculations identify the dynamic resonance along the molecular torsional coordinate between the ground ionic state, D0, and second excited state, D2. Post ionization excitation within the pulse duration transfers the ground state wavepacket to the D2 surface where the wavepacket encounters a three state conical intersection that facilitates the preferred bond dissociation. Time resolved photodissociation experiments measure the dynamics of the launch state, large amplitude oscillations and extended coherence times support the notion that adiabatic ionization populates a majority of the ground ionic surface. Control of the dissociation products is initiated from the launch state by varying the pump wavelength and probe intensity. Elimination of the D0 wavepacket with a 1370 nm reveals additional secondary dynamics that are attributed to wavepacket motion on the D2 surface. Finally, the effect of para substitution on the acetophenone radical cation is explored as a strategy to control the launch state wavepacket dynamics. Suppresion of the wavepacket dynamics are observed with the addition of alkoxy groups whereas extended coherence of the launch state dynamics approaching ~5 ps is observed upon trifluoromethyl substitution. A possible mechanism for the extended coherenece based on coupled torsional rotors is proposed.
Temple University--Theses
Fröbel, Friedrich Georg [Verfasser], Stefanie [Gutachter] Gräfe y Ulf [Gutachter] Peschel. "Attosecond ionization dynamics in a molecular charge-transfer system / Friedrich Georg Fröbel ; Gutachter: Stefanie Gräfe, Ulf Peschel". Jena : Friedrich-Schiller-Universität Jena, 2019. http://d-nb.info/1207273090/34.
Texto completoCHO, HYUCK. "COINCIDENCE DETECTION OF PROTONS AND METASTABLE HYDROGEN ATOMS FROM DISSOCIATIVE IONIZATION OF MOLECULAR HYDROGEN BY ELECTRON IMPACT (TIME-OF-FLIGHT)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188027.
Texto completoLi, Chengjun. "Experimental study on electron impact double ionization dynamics for atomic and small molecular targets at intermediate incident energy". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00867037.
Texto completoEdgü-Fry, Erge. "Single electron capture and ionization involving atomic (and molecular) H and He at low to intermediate impact energies /". Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
Texto completoSavage, Owen Gerard. "The energy and angular distribution of fragment ions produced in the single and double ionization of simple molecules by fast ions". Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334641.
Texto completoO'Connor, Caroline Sophie Scott. "The properties of molecular ions". Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314259.
Texto completoAlexander, Jason S. "Interference effects due to projective-target nucleus scattering in single ionization of molecular hydrogen by 75 keV proton impact". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Alexander_09007dcc8064b51f.pdf.
Texto completoVita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 27, 2009) Includes bibliographical references (p. 70-74).
Callahan, Damien Lee. "The coordination of nickel in hyperaccumulating plants /". Connect to thesis, 2007. http://eprints.unimelb.edu.au/archive/00003773.
Texto completoPhan, Vo Hong Minh. "Cosmic ray interaction in molecular environment". Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7070.
Texto completoIt has been revealed by observational evidences from various experiments at the beginning of the 20th century that the Earth is constantly bombarded by cosmic rays, high-energy particles of extraterrestrial origin. Since these particles are very energetic, it is believed that they could penetrate deep into molecular clouds and ionize the densest parts of these objects where new stars are born. This means that cosmic rays regulate the level of ionization that controls not only the chemistry of molecular clouds but also the coupling between the gas and the magnetic field which support the cloud against gravity during the process of star formation. Interestingly, the ionization rates inferred from infrared and radio observations are much larger than the commonly quoted value in the literature. This calls for a reassessment from a theoretical point of view of the ionization rate in clouds. This task requires a better understanding of the transport of cosmic rays into clouds and, more importantly, the knowledge of the amount of low energy cosmic rays at different positions in our Galaxy. The former has been investigated in some of the pioneering papers in the seventies and eighties but there might be room for some improvements. The latter is known not too long ago at least for the local interstellar medium thanks to the data from the Voyager probes. It is, however, not very clear whether or not these data could be considered as reference values for the density of low energy cosmic rays in the entire Galaxy. The aim of this work is, therefore, to study the propagation of low energy cosmic rays in neutral environments and also to better interpret the observational data of the ionization rate in both isolated molecular clouds and the ones in the vicinity of cosmic accelerators like supernova remnants
Tate, Wendy Rose. "Surface-enhanced laser desorption/ionization time-of-flight mass spectroscopy (SELDI-TOF-MS) as a tool for molecular endpoint analysis of PX-12, a thioredoxin-1 inhibitor". Thesis, The University of Arizona, 2005. http://hdl.handle.net/10150/291852.
Texto completoZhang, Kaikai. "Atomic and Molecular dynamics in intense mid-infrared fields". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440204616.
Texto completoWilbois, Timo Eduard Karl [Verfasser] y Hanspeter [Akademischer Betreuer] Helm. "Single ionization of molecular hydrogen in strong laser fields : : experimental imaging and analysis = Einfachionisation von molekularem Wasserstoff in starken Laserfeldern". Freiburg : Universität, 2011. http://d-nb.info/1123458669/34.
Texto completoTejwani, Ravindra Wadhumal. "EXPERIMENTAL AND MOLECULAR DYNAMICS SIMULATION STUDIES OF PARTITIONING AND TRANSPORT ACROSS LIPID BILAYER MEMBRANES". UKnowledge, 2009. http://uknowledge.uky.edu/gradschool_diss/738.
Texto completoHill, Jacob A. Hill. "SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION IONIZATION TIME OF FLIGHT MASS SPECTROMETRY (SL-MALDI-TOF MS) ANALYSIS OF POLYMER BLEND SURFACE COMPOSITION". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1514479406062149.
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