Date of Award

Spring 2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Committee Director

Peter Bernath

Committee Member

Charles Sukenik

Committee Member

Lepsha Vuskovic

Committee Member

Alex Godunov

Committee Member

Craig Bayse

Abstract

The four most abundant isotopologues (N2O, 15NNO, N15NO, and NN18O) of nitrous oxide have been measured in the Earth's atmosphere by infrared remote sensing with the Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer. These satellite observations have provided a near global picture of N2O isotopic fractionation. The relative abundance of the heavier isotopologues increase with altitude and with latitude in the stratosphere as the air becomes older.

Near global 85°S{85°N atmospheric measurement of carbonyl sulfide (OCS), including the minor OC34S and O13CS isotopologues, were made by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) in low Earth orbit. ACE-FTS data provide volume mixing ratio (VMR) profiles of OCS, OC34S and O13CS from 8 km in the troposphere up to 31 km in the stratosphere. The global zonal and seasonal distributions of OCS isotopologues were studied. OCS observations made with the MkIV balloon-borne Fourier transform spectrometer (FTS) are also presented. The results indicate a slight enrichment of OC34S and a significant enrichment of O13CS as the altitude increases. The contribution of OCS to the background Stratospheric Sulfate Aerosol Layer (SSA) is discussed and ACE-FTS data indicate that OCS is a major contributor.

Vibration-rotation line lists for AlF, Al35Cl and Al37Cl have been prepared in their ground electronic states (X1Σ+). Experimental rotational and ro-vibrational lines were employed to calculate a potential energy surface (PES) by direct potential fit-ting. The PES was used to calculate ro-vibrational energy levels. Born-Openheimer Breakdown (BOB) corrections were included in the energy level calculations for AlCl. Ro-vibrational energy levels were calculated for the v=0 to v=11 vibrational levels and up to Jmax =200 for the rotational levels. Dipole moment functions (DMFs) covering the range of the PES turning points were calculated for AlCl and AlF by ab initio methods and used to determine line intensities. Partition functions for temperatures up to 3000 K were calculated. AlF and AlCl have been detected in circumstellar envelopes and are predicted to occur in cool stellar and sub-stellar atmospheres.

A new line list for the A2Σ+X2Π electronic transition of OH has been calculated. Line positions have been taken from the literature and refitted with Western's PGOPHER program. Line intensities were calculated using a new ab initio Transition Dipole Moment Function (TDMF) obtained with Molpro 2012. The new TDMF and the potential functions from LeRoy's RKR program have been used as input to LeRoy's LEVEL program in order to calculate Transition Dipole Moment Matrix Elements (TDMMEs). These matrix elements were transformed from Hund's case (b) to Hund's case (a) as required for the PGOPHER program. The line list was calculated with PGOPHER for bands with v' = 0 -- 4 in the A2Σ+ state and v'' = 0 -- 9 for the X2Π state.

Methane (CH4) spectra in the ν3 band near 3.3 μm were measured for 0 Torr, 50 Torr, 150 Torr, 240 Torr, 320 Torr, and 400 Torr pressure of added hydrogen. The spectra were recorded using a high resolution Fourier transform spectrometer. The CH4 spectra were measured at 5 different temperatures from room temperature up to ~1100 K. A multi-spectrum non-linear least-squares fit method was used to determine the line parameters at each temperature. Voigt line shape functions were used to determine the broadening and shifting of methane lines in the P and R branches. Additionally, Hartmann{Tran line shape functions (quadratic Speed-Dependent Hard Collision, qSDHC, including line mixing) were used to measure speed dependent line shifting. Temperature-dependence of coefficients were determined from a fit of line parameters as a function of temperature. Finally, the dependence of pressure broadening (γ0) and shift (δ0) parameters on the rotational quantum number (J) was studied.

DOI

10.25777/j9br-ak98

ISBN

9798641486352

ORCID

0000-0002-8282-6943

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