# EUV ABSORPTION SPECTROSCOPY OF SUPERSONIC-JET-COOLED MOLECULES: CO BANDS IN THE WAVELENGTH REGION $\sim$97 nm

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 Title: EUV ABSORPTION SPECTROSCOPY OF SUPERSONIC-JET-COOLED MOLECULES: CO BANDS IN THE WAVELENGTH REGION $\sim$97 nm Creators: Yoshino, K.; Smith, P. L.; Esmond, J. R.; Parkinson, W. H.; Stark, G.; Ito, K. Issue Date: 1992 Publisher: Ohio State University Abstract: Spectra obtained at 295 K show that many CO bands below 100 nm are both overlapped and perturbed. As a consequence, synthetic EUV absorption spectra for CO at the low temperatures that prevail in interstellar clouds are uncertain. In order to simplefy and clarify such band systems, we have developed a supersonic jet expansion apparatus that is used with the 6.65-m vacuum spectrometer at the Photon Factroy, KEK, Japan. A predispersed beam of synchrotron radiation enters a 3-mm diameter hole close to the supersonic jet and defines a section of the jet stream to record molecular absorption. A mixture of carbon monoxide in helium is used. The absorption spectrum of CO at $\sim$25 K in the wavelength region $\sim$97 nm has been investigated photoelectrically with this apparatus. The measured spectrum at $\sim$25 K is in resonable agreement with some published modelled spectra, but our ratios of integrated cross sections of those bands are somewhat different from those determined from low resolution spectra obtained at 295 K. Description: This work is supported by NASA grant NAGW 1596 to Harvard College Observatory Author Institution: Harvard-Smithsonian Center for Astrophysics; Physics Department, Wellesley College; Photon Factory, KEK URI: http://hdl.handle.net/1811/12723 Other Identifiers: 1992-MH-07