IOP Publishing Ltd.;United States: American Astronomical Society
摘要:
摘要： We report measurements of the vacuum ultraviolet (VUV) emission spectra of a microwave-discharge hydrogenflow lamp (MDHL), a common tool in astrochemistry laboratories working on ice VUV photoprocessing. The MDHL provides hydrogen Ly- alpha (121.6 nm) and H sub(2) molecular emission in the 110-180 nm range. We show that the spectral characteristics of the VUV light emitted in this range, in particular the relative proportion of Ly- alpha to molecular emission bands, strongly depend on the pressure of H sub(2) inside the lamp, the lamp geometry (F type versus T type), the gas used (pure H sub(2) versus H sub(2) seeded in He), and the optical properties of the window used (MgF sub(2) versus CaF sub(2)). These different configurations are used to study the VUV irradiation of CO ice at 14 K. In contrast to the majority of studies dedicated to the VUV irradiation of astrophysical ice analogs, which have not taken into consideration the emission spectrum of the MDHL, our results show that the processes induced by photons in CO ice from a broad energy range are different and more complex than the sum of individual processes induced by monochromatic sources spanning the same energy range, as a result of the existence of multistate electronic transitions and discrepancy in absorption cross sections between parent molecules and products in the Ly- alpha and H sub(2) molecular emission ranges. 出版者： United States: American Astronomical Society 出版日期： 2014-01-20 出處： The Astrophysical Journal, 2014-01, Vol.781 (1), p.15--13 資源來源： Institute of Physics Journals 識別號： ISSN: 0004-637X 識別號： EISSN: 1538-4357 識別號： DOI: 10.1088/0004-637x/781/1/15
