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Gas Phase Molecular Spectroscopy: Electronic Spectroscopy of Combustion Intermediates, Chlorine Azide Kinetics, and Rovibrational Energy Transfer in Acetylene

Freel, Keith Allen (2013)
Dissertation (239 pages)
Committee Chair / Thesis Adviser: Heaven, Michael
Committee Members: Kindt, James ; Kaufman, Myron J
Research Fields: Chemistry, Physical; Physics, Molecular
Keywords: spectroscopy; gas phase; combustion; soot formation; chlorine azide; acetylene laser; intermolecular energy transfer; phenyl; phenyoxy; phenyl peroxy; ion kinetics; size selected ion; double resonance; laser
Program: Laney Graduate School, Chemistry
Permanent url: http://pid.emory.edu/ark:/25593/d7khq

Abstract

This dissertation is composed of three sections. The first deals with the electronic spectroscopy of combustion intermediates that are related to the formation of polycyclic aromatic hydrocarbons. Absorption spectra for phenyl, phenoxy, benzyl, and phenyl peroxy radicals were recorded using the technique of cavity ring-down spectroscopy. When possible, molecular constants, vibrational frequencies, and excited state lifetimes for these radicals were derived from these data. The results were supported by theoretical predictions.

The second section presents a study of electron attachment to chlorine azide (ClN3) using a flowing-afterglow Langmuir-probe apparatus. Electron attachment rates were measured to be 3.5x10βˆ’8 and 4.5x10βˆ’8 cm3sβˆ’1 at 298 and 400 K respectively. The reactions of ClN3 with eighteen cations and seventeen anions were characterized. Rate constants were measured using a selected ion flow tube. The ionization energy (>9.6eV), proton affinity (713Β±41 kJ molβˆ’1), and electron affinity (2.48Β±0.2 eV) for ClN3 were determined from these data.

The third section demonstrates the use of double resonance spectroscopy to observe state-selected rovibrational energy transfer from the first overtone asymmetric stretch of acetylene. The total population removal rate constants from various rotational levels of the (1,0,1,00,00) vibrational state were determined to be in the range of (9-17) x 10-10 cm3s-1. Rotational energy transfer accounted for approximately 90% of the total removal rate from each state. Therefore, the upper limit of vibrational energy transfer from the (1,0,1,00,00) state was 10%.

Table of Contents

Section 1: Cavity Ring-down Spectroscopy of Polycyclic Aromatic

Hydrocarbon Transient Species........................................................................ 1

Chapter 1. Introduction to Spectroscopy of Combustion Intermediates.... 1

Bibliography....................................................................................... 12

Chapter 2. Development and Theory of Cavity Ring-down Spectroscopy 15

Bibliography....................................................................................... 21

Chapter 3. Experimental.......................................................................... 22

3.1. Cavity Ring-down Spectrometer.................................................. 24

3.2. Electrical Discharge Assembly.................................................... 26

3.3. Gas Expansion and Cooling........................................................ 30

3.4. LabVIEW Programs.................................................................... 33

Bibliography....................................................................................... 36

Chapter 4. Experimental Optimization.................................................... 37

4.1. Iodine.......................................................................................... 38

4.1.1. Introduction....................................................................... 38
4.1.2. Experimental...................................................................... 39
4.1.3. Results and Discussion....................................................... 40
4.2. C2................................................................................................ 44
4.2.1. Introduction....................................................................... 44
4.2.2. Experimental...................................................................... 45
4.2.3. Results and Discussion....................................................... 46
4.3. C6H............................................................................................ 48
4.3.1. Introduction....................................................................... 48
4.3.2. Experimental...................................................................... 49
4.3.3. Results and Discussion....................................................... 49
4.4. N2+............................................................................................. 52
4.4.1. Introduction....................................................................... 52
4.4.2. Experimental...................................................................... 52
4.4.3. Results and Discussion....................................................... 53
4.5. Redesign of the Valve System.................................................... 56
4.5.1. Introduction....................................................................... 56
4.5.2. Experimental...................................................................... 57
4.5.3. Results and Discussion....................................................... 58
4.6. Dissociation by Pyrolysis............................................................ 59
4.6.1. Introduction....................................................................... 59
4.6.2. Experimental...................................................................... 61

4.6.3. Results and Discussion ...................................................... 62

Bibliography....................................................................................... 68
Chapter 5. The Phenyl Radical................................................................. 70

5.1. Introduction................................................................................ 70

5.2. Experimental............................................................................... 73

5.3. Experimental Results.................................................................. 75

5.4. Theoretical Calculations and Analysis......................................... 80

5.5. Discussion and Conclusions........................................................ 92
Bibliography....................................................................................... 95
Chapter 6. The Phenoxy Radical.............................................................. 97

6.1. Introduction................................................................................ 97

6.2. Experimental............................................................................... 99

6.3. Experimental Results................................................................ 101

6.4. Theoretical Calculations and Analysis....................................... 103

6.5. Discussion and Conclusions...................................................... 115
Bibliography..................................................................................... 120

Chapter 7. The Phenylperoxy Radical.................................................... 123

7.1. Introduction.............................................................................. 123

7.2. Experimental............................................................................. 127

7.3. Experimental Results................................................................ 129

7.4. Theoretical Calculations............................................................ 135

7.5. Discussion................................................................................. 144
Bibliography..................................................................................... 150

Section 2: Chlorine Azide - Electron Attachment and Reactions with

Ions At the Air Force Research Laboratory.................................................. 152

Chapter 8. Electron Attachment to Chlorine Azide............................... 152

8.1. Introduction.............................................................................. 152

8.2. Experimental............................................................................. 155

8.3. Results and Discussion.............................................................. 159

8.4. Conclusions............................................................................... 165

Bibliography..................................................................................... 166

Chapter 9. Reactions of Positive and Negative Ions with ClN3 at 300K 168

9.1. Introduction.............................................................................. 168

9.2. Experimental............................................................................. 169

9.3. Results: ClN3 + Negative Ions.................................................. 171

9.3.1. Negative Ions + Cl2......................................................... 173
9.3.2. Negative Ions + ClN3...................................................... 175

9.4. Discussion: ClN3 + Negative Ions............................................ 178

9.5. Results: ClN3 + Positive Ions................................................... 181

9.6. Discussion: ClN3 + Positive Ions.............................................. 185

Bibliography..................................................................................... 187

Section 3: Rovibrational Energy Transfer in Acetylene................................ 189

Chapter 10. Rotational and Vibrational Energy Transfer From the

First Overtone Stretch (10100)00 of Acetylene..................................... 189

10.1. Introduction............................................................................ 189

10.2. Experimental........................................................................... 193

10.2.1. Double Resonance Spectroscopy................................... 193

10.2.2. Experimental Setup........................................................ 195

10.3. Results and Analysis................................................................ 198

10.3.1. Absorption Spectrum of Acetylene................................ 198

10.3.2. Probe Scan Results and Analysis.................................... 199

10.3.3. Pump Scan Results and Analysis.................................... 202

10.3.4. Time Delay Scan Results and Analysis........................... 207

10.3.5. Quantitative Analysis of Energy Transfer...................... 208

10.3.6. Scaling Law.................................................................... 212
10.3.7. Vibrational Energy Transfer........................................... 214

10.4. Discussion and Conclusions..................................................... 214

Bibliography...................................................................................... 217

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