Investigating multiphoton phenomena using nonlinear dynamics

dc.contributor.advisor Uzer, Turgay
dc.contributor.author Huang, Shu en_US
dc.contributor.committeeMember Aral, Mustafa
dc.contributor.committeeMember Flannery, Raymond
dc.contributor.committeeMember Raman, Chandra
dc.contributor.committeeMember Schatz, Michael
dc.contributor.department Physics en_US
dc.date.accessioned 2008-06-10T20:37:01Z
dc.date.available 2008-06-10T20:37:01Z
dc.date.issued 2008-03-20 en_US
dc.description.abstract Many seemingly simple systems can display extraordinarily complex dynamics which has been studied and uncovered through nonlinear dynamical theory. The leitmotif of this thesis is changing phase-space structures and their (linear or nonlinear) stabilities by adding control functions (which act on the system as external perturbations) to the relevant Hamiltonians. These phase-space structures may be periodic orbits, invariant tori or their stable and unstable manifolds. One-electron systems and diatomic molecules are fundamental and important staging ground for new discoveries in nonlinear dynamics. In past years, increasing emphasis and effort has been put on the control or manipulation of these systems. Recent developments of nonlinear dynamical tools can provide efficient ways of doing so. In the first subtopic of the thesis, we are adding a control function to restore tori at prescribed locations in phase space. In the remainder of the thesis, a control function with parameters is used to change the linear stability of the periodic orbits which govern the processes in question. In this thesis, we report our theoretical analyses on multiphoton ionization of Rydberg atoms exposed to strong microwave fields and the dissociation of diatomic molecules exposed to bichromatic lasers using nonlinear dynamical tools. This thesis is composed of three subtopics. In the first subtopic, we employ local control theory to reduce the stochastic ionization of hydrogen atom in a strong microwave field by adding a relatively small control term to the original Hamiltonian. In the second subtopic, we perform periodic orbit analysis to investigate multiphoton ionization driven by a bichromatic microwave field. Our results show quantitative and qualitative agreement with previous studies, and hence identify the mechanism through which short periodic orbits organize the dynamics in multiphoton ionization. In addition, we achieve substantial time savings with this approach. In the third subtopic we extend our periodic orbit analysis to the dissociation of diatomic molecules driven by a bichromatic laser. In this problem, our results based on periodic orbit analysis again show good agreement with previous work, and hence promise more potential applications of this approach in molecular physics. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/22558
dc.publisher Georgia Institute of Technology en_US
dc.subject Nonlinear dynamics en_US
dc.subject Stochastic ionization en_US
dc.subject Dissociation en_US
dc.subject Periodic orbit en_US
dc.subject Bifurcation en_US
dc.subject Chaos en_US
dc.subject.lcsh Multiphoton processes
dc.subject.lcsh Phase space (Statistical physics)
dc.subject.lcsh Nonlinear theories
dc.subject.lcsh Dynamics
dc.subject.lcsh Rydberg states
dc.title Investigating multiphoton phenomena using nonlinear dynamics en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename College of Sciences
local.contributor.corporatename School of Physics
relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
relation.isOrgUnitOfPublication 2ba39017-11f1-40f4-9bc5-66f17b8f1539
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