Browsing by Author "Liu, SY"

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Developing a multi-dimensional instrument for assessing students' epistemological views toward science
(2005-10-28)
Tsai, CC
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Liu, SY
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教育研究所
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師資培育中心
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Institute of Education
The purpose of this study was to describe the development and validation of an instrument to identify various dimensions of scientific epistemological views (SEVs) held by high school students. The instrument included five SEV dimensions (subscales): the role of social negotiation on science, the invented and creative reality of science, the theory-laden exploration of science, the cultural impacts on science, and the changing features of science. Six hundred and thirteen high school students in Taiwan responded to the instrument. Data analysis indicated that the instrument developed in this study had satisfactory validity and reliability measures. Correlation analysis and in-depth interviews supported the legitimacy of using multiple dimensions in representing student SEVs. Significant differences were found between male and female students, and between students' and their teachers' responses on some SEV dimensions. Suggestions were made about the use of the instrument to examine complicated interplays between SEVs and science learning, to evaluate science instruction, and to understand the cultural differences in epistemological views of science.
Molecular elimination in photolysis of o- and p-fluorotoluene at 193 nm: Internal energy of HF determined with time-resolved Fourier transform spectroscopy
(2005-12-08)
Yang, SK
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Liu, SY
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Chen, HF
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Lee, YP
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應用化學系
Following the photodissociation of o-fluorotoluene [o-C6H4(CH3)F] at 193 nm, rotationally resolved emission spectra of HF(1 <= v <= 4) in the spectral region of 2800-4000 cm(-1) are detected with a step-scan Fourier transform spectrometer. HF(v <= 4) shows nearly Boltzmann-type rotational distributions corresponding to a temperature similar to 1080 K; a short extrapolation from data in the period of 0.5-4.5 mu s leads to a nascent rotational temperature of 1130 +/- 100 K with an average rotational energy of 9 +/- 2 kJ mol(-1). The observed vibrational distribution of (v=1):(v=2):(v=3)=67.6: 23.2: 9.2 corresponds to a vibrational temperature of 5330 +/- 270 K. An average vibrational energy of 25 +/-(12)(3) kJ mol(-1) is derived based on the observed population of HF(1 <= v <= 3) and estimates of the population of HF (v=0 and 4) by extrapolation. Experiments performed on p-fluorotoluene [p-C6H4(CH3)F] yielded similar results with an average rotational energy of 9 +/- 2 kJ mol(-1) and vibrational energy of 26 +/-(12)(3) kJ mol(-1) for HF. The observed distributions of internal energy of HF in both cases are consistent with that expected for four-center elimination. A modified impulse model taking into account geometries and displacement vectors of transition states during bond breaking predicts satisfactorily the rotational excitation of HF. An observed vibrational energy of HF produced from fluorotoluene slightly smaller than that from fluorobenzene might indicate the involvement of seven-membered-ring isomers upon photolysis. (c) American Institute of Physics.