Quantitative Infrared Spectroscopy of Minor Constituents of the Earth's Stratosphere
Charles Chackerian, Jr., and Lawrence P. Giver
Abstract of Research Objectives
We obtain quantitative laboratory spectroscopic measurements of molecular constituents which are of importance in understanding the "health" of the Earth's atmosphere, and in particular emphasize those species which are important for understanding stratospheric kinetics or are used for long term monitoring of the stratosphere. Our measurements provide: (1) line and band intensity values which are needed (a) to establish limits of detectability for as yet unobserved species and (b) to quantify the abundance of those species which are observed, (2) line-positions, -half widths and pressure induced shifts are all needed for remote and in situ sensing techniques, and (3) data on the above basic molecular parameters at temperatures and pressures appropriate to the real atmosphere.
Summary of Progress and Results
A laser magnetic rotation spectrometer operating on the 2P1/2® 2P1/2 transitions of atomic iodine was built which demonstrated a detection limit of 5x106 iodine atoms per cm3 for a 1 Hz bandwidth. High-resolution rovibrational spectra of the 0® 2 vibrational band of CO recorded with a S/N of about 4000 show that at the 1-2% level of accuracy that speed-dependent effects must be used to describe the observed line profiles. Both low- and high-resolution infrared spectra of nitric acid were recorded at the Pacific Northwest National Laboratory/Battelle Wiley Laboratory. Absorption cross sections will be published at 0.1 cm-1 intervals between 820 cm-1 and 5300 cm-1. High-resolution spectra recorded under flow conditions for four strongest infrared bands of nitric acid are being used to determine the intensity contributions of hot-band transitions.
Collaborators: T. Blake, Battelle/Pacific Northwest National Laboratory
L. Brown, Jet Propulsion Laboratory
A. Pine, National Institute of Standards and Technology
S. Sharpe, Battelle/Pacific Northwest National Laboratory
Point of Contact:Charles Chackerian, Jr., SETI, (650) 604-6300, cchackerian@mail.arc.nasa.gov