Hole-burning spectroscopy as a probe of guest-host interactions in amorphous materials.
Item
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Title
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Hole-burning spectroscopy as a probe of guest-host interactions in amorphous materials.
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Identifier
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AAI9510643
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identifier
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9510643
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Creator
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Cavus, Abdullah.
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Contributor
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Adviser: John R. Lombardi
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Date
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1994
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Physical | Physics, Optics | Chemistry, Polymer
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Abstract
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The absorption bands of organic molecules in rigid solvents are, even at low temperatures, quite broad. Typical bandwidths are of the order of several hundreds of wavenumbers. So, condensed phase spectroscopy is limited in its spectral resolution by the inhomogeneous broadening. Irradiation into these inhomogeneously broadened bands with a narrow bandwidth laser can induce resonant molecules to undergo a photochemical or photophysical transformation creating a hole in the absorption spectrum. The systems of concern to us here are those in which photochemically active molecules are present in low concentration as guests in a solid host matrix at low temperatures.;When molecules are embedded in amorphous hosts, it is found that the width of spectral lines are highly sensitive to the nature of the guest-host interaction. The advantage of hole-burning spectroscopy is that it provides the ability to obtain high resolution optical spectra in inherently low resolution situations. Measuring the dipole moment change of a guest molecule in various host matrices may shed some light on guest-host interactions involved with the homogeneous linewidth of the guest, temperature and properties of the host.;The dipole moment difference, {dollar}\Delta\mu\sb{lcub}\rm eff{rcub}{dollar}, between guest molecule in the ground state and the excited state was estimated by using the spectral hole splitting or broadening that results from an applied electric field.;The fluorescence excitation spectroscopy technique was used to study the photochemical hole-burning and investigate the dipole moment change of quinazirine (1,4-dihydroxyanthraquinone) and cresylviolet perchlorate in various glass and polymer hosts such as formamide, ethanol:methanol (EM), polyvinyl alcohol (PVA), poly(2-hydroxyethyl) methacrylate (PHEMA), polyvinylbutyral (PVB), and polymethyl methacrylate (PMMA). The strong correlation between effective dipole moment change of the guest molecule and the dielectric constant of the host matrices illustrated the sensitivity of the dipole moment change as a direct measure of the guest-host interactions.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
