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Measurement of Rotational-State Relaxation by Time-Resolved Infrared Double-Resonance Spectroscopy

  • B. Abel
  • S. Coy
  • C. Flannery
  • J. J. Klaassen
  • J. I. Steinfeld
Conference paper
Part of the Springer Proceedings in Physics book series (SPPHY, volume 74)

Abstract

Many trace species of critical importance in atmospheric processes, notably ozone and methane, can be monitored by remote sensing of their infrared absorption and emission bands. Recovery of accurate column densities and mixing ratios from field measurements requires accurate knowledge of band parameters, viz., assigned line frequencies, line intensities, and pressure-broadened linewidths. The last-named quantities are generally derived from line-broadening models which have been tested against only a limited experimental data base. We have been using time-resolved infrared double-resonance spectroscopy to measure inelastic collision rates, which are a key component of broadening models. A pulsed infrared laser is used to prepare selected rovibrational levels of the species of interest; these are probed by a tunable semiconductor diode laser which provides the resolution necessary for resolution of energy-transfer processes at the state-to-state level. Results obtained for several systems indicate that in many cases the fast-order collision models used to account for rovibrational relaxation and collision broadening are inadequate to describe the inelastic processes in detail, particularly for large J and K changes in collisions.

Keywords

Inelastic Collision Inelastic Process Trace Species Quantum Fourier Transform Rovibrational Level 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1994

Authors and Affiliations

  • B. Abel
    • 1
  • S. Coy
    • 1
  • C. Flannery
    • 1
  • J. J. Klaassen
    • 1
  • J. I. Steinfeld
    • 1
  1. 1.Department of Chemistry and G.R. Harrison Spectroscopy LaboratoryMassachusetts Institute of TechnologyCambridgeUSA

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