Development of methods and instrumentation for molecular optical probing of temperature, pressure and viscosity
Abstract
This thesis details the development of several types of instrumentation and analytical methods for optically measuring temperature, pressure and viscosity. Chapter One details the use of a new optical method to alter the depth of sampling without physically manipulating the sample or changing the spectral resolution. This instrument takes advantage of the unique behavior of fiber optic bundles and charged coupled device detectors to make fluorescence and Raman spectroscopic measurements with varying depth resolutions. Chapter Two employs this instrument to measure pressure gradients in the diamonds of a diamond anvil cell. The pressure in the diamond was studied using shifts measured in the frequency of the Raman spectrum. Chapter Three switches focuses to the use of the fluorescence of a probe molecule, BTBP, to measure temperature. Changes in the fluorescence spectrum taken using a home-built fluorimeter were used to measure temperature with an uncertainty of $\pm 2\sp\circ$C. Temperature was measured in both methanol and mineral oil solutions. The work in Chapter Five studies the extension of this technique to coupling with optical fibers and light emitting diode excitation. The behavior of BTBP doped into a PMMA matrix is studied as a function of temperature. Also, the stability of the probe was tested. Finally, the rotational lifetime of BTBP was evaluated as a universal viscosity probe in Chapter Six. The fluorescence anisotropy of BTBP was measured as a function of viscosity as the viscosity was altered by varying the temperature and pressure of the BTBP solution.
Degree
Ph.D.
Advisors
Ben-Amotz, Purdue University.
Subject Area
Analytical chemistry|Chemistry|Optics
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