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Frequency-Stabilized Cavity Ring-Down Spectroscopy of O₂ and CO₂ to Support Atmospheric Remote Sensing


Long, David Alexander (2012) Frequency-Stabilized Cavity Ring-Down Spectroscopy of O₂ and CO₂ to Support Atmospheric Remote Sensing. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/CTFH-GZ09.


Recent remote-sensing satellite missions have aimed to measure global greenhouse gas concentrations with precisions as demanding as 0.25%. These high-resolution measurements should allow for the quantification of carbon sources and sinks, thus, allowing for a considerable reduction in present carbon cycle uncertainties. To achieve these unprecedented measurement goals will require the most precise body of spectroscopic reference data (i.e., laboratory measurements) ever assembled. In order to aid these missions, we have measured ultraprecise spectroscopic parameters for the (30012) ←(00001) CO2 band at 1.57 µm and the O2 A-band at 0.76 µm. These near-infrared transitions are utilized in recent greenhouse gas monitoring missions, with the A-band being employed to derive pressure and temperature profiles. In these investigations we have employed frequency-stabilized cavity ring-down spectroscopy (FS-CRDS), a novel ultrasensitive spectroscopic technique. In the O2 A-band we have measured magnetic dipole line parameters for 16O2 as well as each of the rare isotopologues and have produced calculated, HITRAN-style line lists. Due to the clear presence of collisional narrowing in the spectra, we have utilized the Galatry line profile in these studies and have reported narrowing parameters under self- and air-broadened conditions. We anticipate that the use of these spectral parameters will greatly reduce the uncertainties of atmospheric remote-sensing retrievals. In addition, the spectral fidelity of FS-CRDS allowed us to observe and quantify unresolved hyperfine structure for the 17O-containing isotopologues. Furthermore, the high sensitivity of FS-CRDS enabled measurements of ultraweak (S~10−30 cm molec.−1) electric quadrupole transitions in the A-band, many of which had not previously been observed. Recently we have begun a series of studies of the near-infrared CO2 transitions. Measurements at low pressures (<40 kPa) have revealed the simultaneous presence of Dicke narrowing and speed dependence of collisional broadening and shifting. In addition, we have demonstrated that the use of the simple Voigt profile (which neglects these effects) in the pressure range will lead to several percent biases in the retrieved Lorentzian width and spectral area.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Oxygen; Carbon Dioxide; Remote Sensing; Cavity Ring-Down Spectroscopy; Collisional Narrowing; Frequency-Stabilized Cavity Ring-Down Spectroscopy; A-band; Near-Infrared
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Okumura, Mitchio
Thesis Committee:
  • Blake, Geoffrey A. (chair)
  • Miller, Thomas F.
  • McKoy, Basil Vincent
  • Miller, Charles E.
  • Okumura, Mitchio
Defense Date:8 August 2011
Funding AgencyGrant Number
National Science FoundationGraduate Research Fellowship
National Defense Science and Engineering Graduate FellowshipUNSPECIFIED
NASA Upper Atmospheric Research Program NNG06GD88G
NASA Upper Atmospheric Research ProgramNNX09AE21G
NASA Atmospheric Carbon Observations from Space (ACOS)104127-04.02.02
NIST Greenhouse Gas Measurements and Climate Research ProgramUNSPECIFIED
Record Number:CaltechTHESIS:06282011-172416252
Persistent URL:
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Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6531
Deposited By: David Long
Deposited On:25 Aug 2011 18:48
Last Modified:03 Oct 2019 23:52

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