CaltechTHESIS
  A Caltech Library Service

Cavity ringdown spectroscopy of the nitrate and peroxy radicals

Citation

Takematsu, Kana (2011) Cavity ringdown spectroscopy of the nitrate and peroxy radicals. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:06012011-114553466

Abstract

The chemistry of the Earth's atmosphere consists of complex networks of reactions. Photooxidation of volatile organic compounds (VOCs) in the atmosphere initiates free radical formation. These radicals attack other VOCs to form pollutants and secondary organic aerosols. Quantitative understanding of the radicals and reactions is needed for accurate modeling of the atmosphere. Many species are difficult to study due to low concentrations and short lifetimes. Spectroscopic methods in the ultraviolet and visible regions either do not have the sensitivity or the specificity to characterize these reactions. The work here examines the chemistry and physics of atmospheric radicals by using the sensitive and fast spectroscopic technique cavity ringdown spectroscopy (CRDS), to detect transient species in the near-infrared (NIR) region. The nitrate radical NO3 is a major nighttime oxidant in the troposphere. It is also a classic example of the breakdown of the Born-Oppenheimer approximation. The radical was first observed a century ago in atmospheric measurements. The structures of the three lowest electronic state however are still not well understood. Difficulties arise from the non-adiabatic Jahn Teller and Pseudo-Jahn-Teller effects. In Chapter 3, we examine the electronic-dipole forbidden transition of NO3 in the NIR to elucidate the à state of NO3. In Chapter 4, we examine the role of NO3 in atmospheric reactions by detecting the peroxy radical intermediate of the oxidation of 2-butene by NO3. The chlorine atom Cl is highly reactive and has been historically considered a coastal or marine layer oxidant. Studies now indicate that Cl atoms can play significant roles in urban mainland chemistry. Isoprene and 2-methyl-3-buten-2-ol (MBO232) are two important biogenic VOC emissions. Isoprene alone is responsible for emissions of 500 Tg C y-1. The peroxy radical intermediates of the oxidation of isoprene and MBO232 by Cl have never been detected using absorption spectroscopy. Chapter 5 includes the first preliminary CRD spectra of the transition of Cl-isoprenyl and Cl-MBO232 peroxy radials in the NIR. We also outline kinetic experiments to measure the rates of reaction between the Cl-substituted peroxy radicals and nitric oxide (NO) and hydroperoxy radical (HO2) under high and low NOx conditions in the troposphere.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:cavity ringdown spectroscopy; nitrate; Jahn Teller; peroxy; atmospheric; radicals
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Mixed availability, specified at file level
Research Advisor(s):
  • Okumura, Mitchio
Thesis Committee:
  • Okumura, Mitchio
  • Blake, Geoffrey A. (chair)
  • Gray, Harry B.
  • Marcus, Rudolph A.
Defense Date:23 May 2011
Author Email:kana (AT) caltech.edu
Funders:
Funding AgencyGrant Number
NSFUNSPECIFIED
Environmental Protection AgencyUNSPECIFIED
Record Number:CaltechTHESIS:06012011-114553466
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:06012011-114553466
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6485
Collection:CaltechTHESIS
Deposited By: Kana Takematsu
Deposited On:01 Jun 2011 22:24
Last Modified:16 Apr 2013 23:30

Thesis Files

[img] PDF (Complete thesis) - Final Version
Restricted to Caltech community only until 19 June 2021.
See Usage Policy.

1646Kb
[img]
Preview
PDF (Abstract and table of contents) - Final Version
See Usage Policy.

131Kb
[img]
Preview
PDF (Chapter 1: Introduction) - Final Version
See Usage Policy.

186Kb
[img]
Preview
PDF (Chapter 2: Cavity ringdown spectroscopy and the apparatus) - Final Version
See Usage Policy.

188Kb
[img]
Preview
PDF (Appendix for Chapter 2) - Final Version
See Usage Policy.

365Kb
[img] PDF (Chapter 3: The Nitrate Radical) - Final Version
Restricted to Caltech community only until 19 June 2021.
See Usage Policy.

458Kb
[img] PDF (Appendix for Chapter 3) - Final Version
Restricted to Caltech community only until 19 June 2021.
See Usage Policy.

526Kb
[img] PDF (Chapter 4: NO3-peroxy radicals) - Final Version
Restricted to Caltech community only until 19 June 2021.
See Usage Policy.

223Kb
[img] PDF (Appendix for Chapter 4) - Final Version
Restricted to Caltech community only until 19 June 2021.
See Usage Policy.

119Kb
[img] PDF (Chapter 5: Cl-peroxy radicals) - Final Version
Restricted to Caltech community only until 19 June 2021.
See Usage Policy.

329Kb

Repository Staff Only: item control page