I. Two-photon spectroscopic characterization of the properties of (1) Naturally occurring peridinin in solution and in PCP complex and (2) Synthetic porphyrin and chlorin compounds. II. Online pre-lecture quiz design for optimization of student learning and assessment in a first semester general chemistry lecture course for non-science majors

Date of Completion

January 2007

Keywords

Chemistry, Organic|Education, Sciences

Degree

Ph.D.

Abstract

The two-photon spectroscopic technique is applied to analyze the optical properties of synthetic porphyrin, chlorin, and chlorin-like compounds. All two-photon spectra that were obtained for four compounds have shown similar characteristics that the vibronic transition of the lowest excited state at around 16.8 kK (∼600 nm) is the most intense two-photon band in the visible spectral region. Further computational analysis is suggested to fully characterize this behavior. The other compound analyzed using two-photon spectroscopic method is a naturally occurring peridinin from Amphidinium carterae. Peridinin absorbs light in the UV-Vis regions. However, many spectroscopic and computational studies suggest the existence of the spectroscopic inactive, electronic singlet excited state of the lower transition energy. The two-photon spectroscopic method is advantageous for characterizing optical properties of such one-photon forbidden (invisible) transitions. The obtained two-photon spectrum almost coincides with one-photon spectrum, with the vibronic feature which originated from the lowest electronic singlet excited state. Three lower singlet excited states have been distinguished in the two-photon ratio spectra, and these states have been analyzed computationally. ^ The second part of this dissertation investigates the design of online pre-lecture quizzes. Based on the previously observed effects of online pre-lecture quizzes on student learning in an organic chemistry course for non-major, pre-professional students, similar pre-lecture quiz assignments have been implemented to a general chemistry course for non-science major students. An online pre-lecture quiz consists of five multiple-choice questions which have been randomly selected from question database. Students were given various numbers of attempts for each quiz. According to the quantitative data analysis of pre-lecture quizzes and post-tests, the recommended number of attempts for pre-lecture quiz assignments is five for this group of students to optimize student learning. However, the quiz data shows that the quiz scores are dependent on quiz question difficulty and content difficulty. This experiment must be repeated for a more precise analysis of the effect of this online pre-lecture quiz design. The qualitative analyses of student opinions from survey data are presented and discussed together with the effects of possible factors affecting students' test scores. ^

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