Theses and Dissertations at Montana State University (MSU)
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Item Quantitative multiphoton absorption spectroscopy(Montana State University - Bozeman, College of Letters & Science, 2018) Mikhaylov, Alexander Evgen'evich; Chairperson, Graduate Committee: Aleksander RebaneMultiphoton absorption (MPA) is an intriguing photophysical process that has been found useful for diverse areas of science. Low probabilities of MPA processes in molecular systems require to use intense photon fluxes that can be generated by femtosecond laser sources. Performing MPA measurements with sufficient precision requires a detailed characterization of the photon flux values that poses many technical difficulties. However, if the MPA values are determined accurately, then a quantitative analysis of the data obtained can be used to derive information about many important molecular parameters. As an example of MPA spectroscopy we discuss here two-photon absorption (2PA) methods. 2PA spectroscopy is applied to elucidate the structure-property relationships in different types of molecular systems including Pt-based chromophores, pyrrolo-pyrol complexes, organometallic ferrocene compounds, porphyrin oligomers and DNA base fluorescent analogs. Such spectroscopic analysis allows to shed some light on questions of inversion symmetry breaking effects and charge transfer on molecular scales. The measured 2PA spectra are also used to test several approximations for 2PA cross section expressions by comparing the values of molecular parameters derived from the measured 2PA data with other methods and literature data. We employ different experimental methods including two-photon excited fluorescence and nonlinear transmittance to measure 2PA spectra in a broad range of excitation wavelengths. The success achieved with 2PA based methods stimulates interest in three-photon absorption (3PA) measurements. We report on a progress achieved in 3PA measurements using three-photon excited fluorescence. This method is used to measure 3PA spectra of common fluorescent standards including Fluorescein and Rhodamine 6G and other organic dyes in different solvents. Effects of third harmonic generation and solvents absorption are discussed concerning the reliability of the 3PA measurements.Item Two-step excitation and direct two-photon absorption in Tb 3+: LiYF 4(Montana State University - Bozeman, College of Letters & Science, 1990) Jones, Raymond PaulItem Two-photon spectroscopy of inductively perturbed naphthalenes(Montana State University - Bozeman, College of Letters & Science, 1987) Jones, Richard DwightItem Local response theory of surface plasmons in the space-charge layer of GaAs (110)(Montana State University - Bozeman, College of Letters & Science, 1989) Xu, BingruoItem Collision of photons by the use of x-rays(Montana State University - Bozeman, College of Letters & Science, 1940) Wiegand, Roy V.Item Two-photon absorption and two-photon-resonant four-wave mixing for the Tb^3+ ion in insulators(Montana State University - Bozeman, College of Letters & Science, 1987) Huang, JinItem Thermodynamic interpretation of secondary ion and photon emission during sputtering of silicon(Montana State University - Bozeman, College of Letters & Science, 1977) Burghard, Ronald AlbertItem One and two photon excitation properties of selected biologically important molecules(Montana State University - Bozeman, College of Letters & Science, 1983) Anderson, Bruce EldonItem Design and synthesis of dendrimers for studying two-photon absorption characteristics(Montana State University - Bozeman, College of Letters & Science, 2007) Sims, Michael Keith; Chairperson, Graduate Committee: Charles W. SpanglerWhile entering a technologically advanced world, where inventions of weapons occur rapidly, there is a constant need for research leading up to and preventing these weapons from being harmful. The use of lasers as an eye-damaging agent is one such weapon that requires the construction of good optical limiting materials that combat the harmful effects of these lasers. Optical power limiting materials should have the capability to respond quickly as well as span a large frequency range. Over the last two years, research has been conducted on the synthesis and absorption characteristics of new dendrimers incorporating from 3-6 chromophores that are capable of optical limiting of laser pulses in the visible region (400-600 nm) of the spectrum. These chromophores have been coupled to two new core molecules based on thiophosphoryl and cyclophosphazene derivatives by Wittig methodology yielding G-0 dendrimers with high chromophore density.