<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Q. Chen</style></author><author><style face="normal" font="default" size="100%">Y. Liu</style></author><author><style face="normal" font="default" size="100%">Donahue, N. M.</style></author><author><style face="normal" font="default" size="100%">Shilling, J. E.</style></author><author><style face="normal" font="default" size="100%">Martin, S. T.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Particle-phase chemistry of secondary organic material: Modeled compared to measured O:C and H:C elemental ratios provide constraints</style></title><secondary-title><style face="normal" font="default" size="100%">Environmental Science and Technology</style></secondary-title><short-title><style face="normal" font="default" size="100%">Environ. Sci. Technol.</style></short-title></titles><dates><year><style  face="normal" font="default" size="100%">2011</style></year><pub-dates><date><style  face="normal" font="default" size="100%">Jun</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">11</style></number><volume><style face="normal" font="default" size="100%">45</style></volume><pages><style face="normal" font="default" size="100%">4763-4770</style></pages><isbn><style face="normal" font="default" size="100%">0013-936X</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Chemical mechanisms for the production of secondary organic material (SOM) are developed in focused laboratory studies but widely used in the complex modeling context of the atmosphere. Given this extrapolation, a stringent testing of the mechanisms is important. In addition to particle mass yield as a typical standard for model-measurement comparison, particle composition expressed as O:C and H:C elemental ratios can serve as a higher dimensional constraint. A paradigm for doing so is developed herein for SOM production from a C(5)-C(10)-C(15) terpene sequence, namely isoprene, a-pinene, and beta-caryopyhllene. The model MCM-SIMPOL is introduced based on the Master Chemical Mechanism (MCM v3.2) and a group contribution method for vapor pressures (SIMPOL). The O:C and H:C ratios of the SOM are measured using an Aerosol Mass Spectrometer (AMS). Detailed SOM-specific AMS calibrations for the organic contribution to the H(2)O(+) and CO(+) ions indicate that published O:C and H:C ratios for SOM are systematically too low. Overall, the measurement-model gap was small for particle mass yield but significant for particle-average elemental composition. The implication is that a key chemical pathway is missing from the chemical mechanism. The data can be explained by the particle-phase homolytic decomposition of organic hydroperoxides and subsequent alkyl-radical-promoted oligomerization.&lt;/p&gt;</style></abstract><accession-num><style face="normal" font="default" size="100%">WOS:000291128700017</style></accession-num><notes><style face="normal" font="default" size="100%">&lt;p&gt;Chen, Qi Liu, Yingjun Donahue, Neil M. Shilling, John E. Martin, Scot T.&lt;/p&gt;</style></notes></record></records></xml>