@article{WolfSanchezYangetal.2019, author = {Wolf, Thomas J. A. and Sanchez, David M. and Yang, J. and Parrish, R. M. and Nunes, J. P. F. and Centurion, M. and Coffee, R. and Cryan, J. P. and G{\"u}hr, Markus and Hegazy, Kareem and Kirrander, Adam and Li, R. K. and Ruddock, J. and Shen, Xiaozhe and Vecchione, T. and Weathersby, S. P. and Weber, Peter M. and Wilkin, K. and Yong, Haiwang and Zheng, Q. and Wang, X. J. and Minitti, Michael P. and Martinez, Todd J.}, title = {The photochemical ring-opening of 1,3-cyclohexadiene imaged by ultrafast electron diffraction}, series = {Nature chemistry}, volume = {11}, journal = {Nature chemistry}, number = {6}, publisher = {Nature Publ. Group}, address = {London}, issn = {1755-4330}, doi = {10.1038/s41557-019-0252-7}, pages = {504 -- 509}, year = {2019}, abstract = {The ultrafast photoinduced ring-opening of 1,3-cyclohexadiene constitutes a textbook example of electrocyclic reactions in organic chemistry and a model for photobiological reactions in vitamin D synthesis. Although the relaxation from the photoexcited electronic state during the ring-opening has been investigated in numerous studies, the accompanying changes in atomic distance have not been resolved. Here we present a direct and unambiguous observation of the ring-opening reaction path on the femtosecond timescale and subangstrom length scale using megaelectronvolt ultrafast electron diffraction. We followed the carbon-carbon bond dissociation and the structural opening of the 1,3-cyclohexadiene ring by the direct measurement of time-dependent changes in the distribution of interatomic distances. We observed a substantial acceleration of the ring-opening motion after internal conversion to the ground state due to a steepening of the electronic potential gradient towards the product minima. The ring-opening motion transforms into rotation of the terminal ethylene groups in the photoproduct 1,3,5-hexatriene on the subpicosecond timescale.}, language = {en} } @article{HermannsKeller2021, author = {Hermanns, Jolanda and Keller, David}, title = {How do preservice chemistry teachers rate tasks following the construct of school-related content knowledge in a concept-orientated course on organic chemistry?}, series = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society}, volume = {98}, journal = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society}, number = {11}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-9584}, doi = {10.1021/acs.jchemed.1c00593}, pages = {3442 -- 3449}, year = {2021}, abstract = {In this paper, we describe a study on tasks following the construct of school-related content knowledge. We know from previous studies that such tasks were rated by the preservice chemistry teachers as important for their future profession. Those studies were conducted in a traditional course on organic chemistry which was organized around chemical families. Therefore, we used and evaluated the tasks again in a new course on organic chemistry which is organized around basic concepts in organic chemistry. The results of this evaluation show that the students rate the tasks equally well but use other arguments for their rating. They do not focus only on the content of the tasks and whether this content belongs to the school curriculum or not. The students of the conceptual course rated the content more often (95\%) as important for their future profession compared with the students in the traditional course (57\%). Both groups of students rated the importance of the nature of the task the same way.}, language = {en} }