dc.creator Shubert, V. Alvin en_US dc.creator Pratt, Stephen T. en_US dc.date.accessioned 2010-07-12T13:44:00Z dc.date.available 2010-07-12T13:44:00Z dc.date.issued 2010 en_US dc.identifier 2010-RE-08 en_US dc.identifier.uri http://hdl.handle.net/1811/46008 dc.description Author Institution: Argonne National Laboratory, Chemical Sciences and Engineering Division, Argonne, IL 60439 en_US dc.description.abstract Acetaldehyde was photodissociated with near UV laser light, and the methyl (CH$_3$) and formyl (HCO) radical fragments were photoionized with vacuum ultraviolet (VUV) light. The fragments were detected by using both time of flight mass spectrometry and velocity ion map imaging. With the former technique, simultaneous detection of both fragments provided the intensity of HCO$^{+}$ relative to CH$_3^{+}$ with I(HCO$^{+}$)/I(CH$_3^{+}$) $\approx$ 0.8. Because the absolute photoionization cross section of the CH$_3$ radical has been characterized ( $\approx$ 5 Mb) at the VUV energies of interest, the absolute photoionization cross section of HCO could be determined from the intensity ratio, yielding an HCO cross section of $\approx$ 4 Mb at 10.3 eV. However, because some of the HCO fragments could be formed with enough internal energy to undergo secondary dissociation, velocity ion map imaging was employed to determine the extent of any secondary dissociation that occurred. The translational energy distributions obtained for both the CH$_3$ and HCO fragments are nearly identical, indicating that no HCO fragments underwent secondary dissociation. A surprising result was the smaller photoionization cross section of HCO relative to CH$_3$. Comparison to the isoelectronic species of NO will be discussed and a potential explanation will be offered for this observation. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences under contract No. DE-AC02-06CH11357. en_US dc.language.iso en en_US dc.publisher Ohio State University en_US dc.title PHOTODISSOCIATION OF ACETALDEHYDE AND THE PHOTOIONIZATION CROSS SECTION OF HCO en_US dc.type Article en_US
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