The H atom production channels in the ultraviolet （UV） photochemistry of m-pyridyl radical （m-C5H4N） were investigated at excitation wavelengths from 224 nm to 248 nm by high-n Rydberg atom time-of-flight （HRTOF...
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The H atom production channels in the ultraviolet （UV） photochemistry of m-pyridyl radical （m-C5H4N） were investigated at excitation wavelengths from 224 nm to 248 nm by high-n Rydberg atom time-of-flight （HRTOF） technique. The photofragment yield （PFY） spectrum of the H atoms indicates a broad UV absorption feature near 234 nm. The product kinetic energy release is small; the average product kinetic energy at the wavelengths from 224 nm to 248 nm is 0.12 to 0.19 of the maximum excess energy （assuming the lowest energy product channel, H＋cyanovinylacetylene）. The product kinetic energy distributions are consistent with the H cyanovinylacetylene, H 3,4-pyridyne, and H 2,3-pyridyne product channels, with H cyanovinylacetylene as the main H-loss channel. The angular distributions of the H-atom products are isotropic. After the UV electronic excitation, the m-pyridyl radical undergoes internal conversion to the ground electronic state and then unimolecular dissoci-ation to the H cyanovinylacetylene, H 3,4-pyridyne, and H 2,3-pyridyne products. The dissociation mechanism of the m-pyridyl radical is similar to that of the o-pyridyl radical reported in the early study.
美国2010年发布的数学共同核心课程标准（Common Core State Standards for Mathematics,简称CCSSM）旨在改变教学实践,提供高质量的数学教育（National Governors Association Center for Best Practices＆Council of Chief State Scho...
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美国2010年发布的数学共同核心课程标准（Common Core State Standards for Mathematics,简称CCSSM）旨在改变教学实践,提供高质量的数学教育（National Governors Association Center for Best Practices＆Council of Chief State School Officers,2010）.然而,如何更好地帮助任课教师在教学中有效地应用数学共同核心课程标准是一项艰巨的任务.
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