Spectroscopic identification of water-oxygen and water-hydroxyl complexes and their importance to icy outer solar system bodies

Paul Cooper

Research output: ThesisDoctoral Thesis

105 Downloads (Pure)

Abstract

This thesis studies hydrated oxygen and hydroxyl radicals as a basis for understanding the species formed in the icy surfaces of outer solar system bodies. Infrared spectroscopy is used to identify the species water-oxygen (H2O·O2) and water-hydroxyl (H2O·HO) complexes in inert gas matrices and presents a new mechanism for O2 formation in irradiated ices. The H2O·O2 Complex -- The H2O·O2 complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of H2O⁄O2⁄Ar matrices. Absorption bands at 3731.6, 3638.3, 1590.2⁄1593.6 and 1551.9⁄1548.8 cm-1 were respectively assigned to asymmetric OH water stretching, symmetric OH water stretching, H2O bending, and the O2 stretching vibrations. This experimental data was in good agreement with the results of quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·O2. These calculations gave a binding energy of 0.72 kcal mol-1 for the complex. The H2O·HO Complex -- The H2O·HO complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of OH⁄H2O⁄Ar matrices. The OH was formed in a Tesla coil discharge of an H2O⁄Ar gas stream. This gas stream also provided the source of H2O and Ar needed for the experiments. Three absorption bands were assigned to the OH stretch of the hydroxyl group in the complex. These three bands were caused by the occupancy of three different lattice sites. This experimental data was in good agreement with quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·HO. These calculations gave a binding energy of 5.69 kcal mol-1 for the complex. O2 Formation in Irradiated Ice -- A new mechanism for O2 formation in irradiated ice is presented. This mechanism draws on experimental evidence in the literature to explain the observations of solid O2 on or near the surface of the icy Galilean satellites, Europa and Ganymede. It is proposed that on these bodies, hydrogen peroxide, formed from the radiolysis and photolysis of the ice, is present in highly localized aggregates that hinder O2 diffusion out of the icy surface into the tenuous atmosphere. Further radiolysis and photolysis of these hydrogen peroxide aggregates can then lead to O2 formation via the formation of a short lived water-oxygen atom complex, H2O·O. The O atoms of a pair of these complexes then react rapidly to form O2
Original languageEnglish
QualificationDoctor of Philosophy
Publication statusUnpublished - 2005

Fingerprint

Solar system
Hydroxyl Radical
Oxygen
Water
Ice
Stretching
Radiolysis
Argon
Photolysis
Vibrational spectra
Binding energy
Hydrogen Peroxide
Absorption spectra
Gases
Infrared radiation
Noble Gases
Bending (forming)
Atoms
Infrared spectroscopy
Reactive Oxygen Species

Cite this

@phdthesis{d269c4eb28444babb41514708aa82fda,
title = "Spectroscopic identification of water-oxygen and water-hydroxyl complexes and their importance to icy outer solar system bodies",
abstract = "This thesis studies hydrated oxygen and hydroxyl radicals as a basis for understanding the species formed in the icy surfaces of outer solar system bodies. Infrared spectroscopy is used to identify the species water-oxygen (H2O·O2) and water-hydroxyl (H2O·HO) complexes in inert gas matrices and presents a new mechanism for O2 formation in irradiated ices. The H2O·O2 Complex -- The H2O·O2 complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of H2O⁄O2⁄Ar matrices. Absorption bands at 3731.6, 3638.3, 1590.2⁄1593.6 and 1551.9⁄1548.8 cm-1 were respectively assigned to asymmetric OH water stretching, symmetric OH water stretching, H2O bending, and the O2 stretching vibrations. This experimental data was in good agreement with the results of quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·O2. These calculations gave a binding energy of 0.72 kcal mol-1 for the complex. The H2O·HO Complex -- The H2O·HO complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of OH⁄H2O⁄Ar matrices. The OH was formed in a Tesla coil discharge of an H2O⁄Ar gas stream. This gas stream also provided the source of H2O and Ar needed for the experiments. Three absorption bands were assigned to the OH stretch of the hydroxyl group in the complex. These three bands were caused by the occupancy of three different lattice sites. This experimental data was in good agreement with quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·HO. These calculations gave a binding energy of 5.69 kcal mol-1 for the complex. O2 Formation in Irradiated Ice -- A new mechanism for O2 formation in irradiated ice is presented. This mechanism draws on experimental evidence in the literature to explain the observations of solid O2 on or near the surface of the icy Galilean satellites, Europa and Ganymede. It is proposed that on these bodies, hydrogen peroxide, formed from the radiolysis and photolysis of the ice, is present in highly localized aggregates that hinder O2 diffusion out of the icy surface into the tenuous atmosphere. Further radiolysis and photolysis of these hydrogen peroxide aggregates can then lead to O2 formation via the formation of a short lived water-oxygen atom complex, H2O·O. The O atoms of a pair of these complexes then react rapidly to form O2",
keywords = "Hydroxyl group, Infrared spectroscopy, Oxygen at low temperatures, Europa (Satellite), Ganymede (Satellite), Water-oxygen complex, Water-hydroxyl complex, Oxygen production in ice",
author = "Paul Cooper",
year = "2005",
language = "English",

}

TY - THES

T1 - Spectroscopic identification of water-oxygen and water-hydroxyl complexes and their importance to icy outer solar system bodies

AU - Cooper, Paul

PY - 2005

Y1 - 2005

N2 - This thesis studies hydrated oxygen and hydroxyl radicals as a basis for understanding the species formed in the icy surfaces of outer solar system bodies. Infrared spectroscopy is used to identify the species water-oxygen (H2O·O2) and water-hydroxyl (H2O·HO) complexes in inert gas matrices and presents a new mechanism for O2 formation in irradiated ices. The H2O·O2 Complex -- The H2O·O2 complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of H2O⁄O2⁄Ar matrices. Absorption bands at 3731.6, 3638.3, 1590.2⁄1593.6 and 1551.9⁄1548.8 cm-1 were respectively assigned to asymmetric OH water stretching, symmetric OH water stretching, H2O bending, and the O2 stretching vibrations. This experimental data was in good agreement with the results of quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·O2. These calculations gave a binding energy of 0.72 kcal mol-1 for the complex. The H2O·HO Complex -- The H2O·HO complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of OH⁄H2O⁄Ar matrices. The OH was formed in a Tesla coil discharge of an H2O⁄Ar gas stream. This gas stream also provided the source of H2O and Ar needed for the experiments. Three absorption bands were assigned to the OH stretch of the hydroxyl group in the complex. These three bands were caused by the occupancy of three different lattice sites. This experimental data was in good agreement with quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·HO. These calculations gave a binding energy of 5.69 kcal mol-1 for the complex. O2 Formation in Irradiated Ice -- A new mechanism for O2 formation in irradiated ice is presented. This mechanism draws on experimental evidence in the literature to explain the observations of solid O2 on or near the surface of the icy Galilean satellites, Europa and Ganymede. It is proposed that on these bodies, hydrogen peroxide, formed from the radiolysis and photolysis of the ice, is present in highly localized aggregates that hinder O2 diffusion out of the icy surface into the tenuous atmosphere. Further radiolysis and photolysis of these hydrogen peroxide aggregates can then lead to O2 formation via the formation of a short lived water-oxygen atom complex, H2O·O. The O atoms of a pair of these complexes then react rapidly to form O2

AB - This thesis studies hydrated oxygen and hydroxyl radicals as a basis for understanding the species formed in the icy surfaces of outer solar system bodies. Infrared spectroscopy is used to identify the species water-oxygen (H2O·O2) and water-hydroxyl (H2O·HO) complexes in inert gas matrices and presents a new mechanism for O2 formation in irradiated ices. The H2O·O2 Complex -- The H2O·O2 complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of H2O⁄O2⁄Ar matrices. Absorption bands at 3731.6, 3638.3, 1590.2⁄1593.6 and 1551.9⁄1548.8 cm-1 were respectively assigned to asymmetric OH water stretching, symmetric OH water stretching, H2O bending, and the O2 stretching vibrations. This experimental data was in good agreement with the results of quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·O2. These calculations gave a binding energy of 0.72 kcal mol-1 for the complex. The H2O·HO Complex -- The H2O·HO complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of OH⁄H2O⁄Ar matrices. The OH was formed in a Tesla coil discharge of an H2O⁄Ar gas stream. This gas stream also provided the source of H2O and Ar needed for the experiments. Three absorption bands were assigned to the OH stretch of the hydroxyl group in the complex. These three bands were caused by the occupancy of three different lattice sites. This experimental data was in good agreement with quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·HO. These calculations gave a binding energy of 5.69 kcal mol-1 for the complex. O2 Formation in Irradiated Ice -- A new mechanism for O2 formation in irradiated ice is presented. This mechanism draws on experimental evidence in the literature to explain the observations of solid O2 on or near the surface of the icy Galilean satellites, Europa and Ganymede. It is proposed that on these bodies, hydrogen peroxide, formed from the radiolysis and photolysis of the ice, is present in highly localized aggregates that hinder O2 diffusion out of the icy surface into the tenuous atmosphere. Further radiolysis and photolysis of these hydrogen peroxide aggregates can then lead to O2 formation via the formation of a short lived water-oxygen atom complex, H2O·O. The O atoms of a pair of these complexes then react rapidly to form O2

KW - Hydroxyl group

KW - Infrared spectroscopy

KW - Oxygen at low temperatures

KW - Europa (Satellite)

KW - Ganymede (Satellite)

KW - Water-oxygen complex

KW - Water-hydroxyl complex

KW - Oxygen production in ice

M3 - Doctoral Thesis

ER -