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Start Over Author "Qian, Pu" Publisher american chemical society (acs)
20 results on '"Qian, Pu"'

10. Localized Excitations on the B850a and B850b Bacteriochlorophylls in the LH2 Antenna Complex from Rhodospirillum molischianum As Probed by the Shifts of the Carotenoid Absorption

Author

Nagae Hiroyoshi, Qian Pu, Watanabe Yasutaka, Koyama Yasushi, Zhang Jian-Ping, Limantara Leenawaty, and Fujii Ritsuko

Subjects
Physics, Rhodospirillum, Annihilation, Photochemistry, Molecular physics, Surfaces, Coatings and Films, Blueshift, Delocalized electron, Dipole, chemistry.chemical_compound, chemistry, Materials Chemistry, Bacteriochlorophyll, Physical and Theoretical Chemistry, Absorption (electromagnetic radiation), Excitation
Abstract

Changes in the carotenoid (Car) 1Bu+ absorption upon excitation (using a photon density of 1015photons cm-2) of bacteriochlorophyll (BChl) in the LH2 complex from Rhodospirillum molischianumwere traced with subpicosecond time resolution. The absorption changes could be empirically fit by two components showing a blue shift and a red shift in a ratio of 1:3.6. The shifts of Car absorption were explained in terms of interaction between change in dipole moment upon the 1Bu+ ← ground transition of Car and that upon the Qy ← ground transition of BChl. Calculations of the shifts for three different types of excitation in the B850 ring of the LH2 complex, i.e., (i) localized excitation on B850a or B850b, (ii) partially delocalized excitation over four B850s, and (iii) completely delocalized excitation over the B850 ring predicted the Car shifts with direction (relative magnitude), (i) a blue shift (1) or a red shift (3.3), (ii) a red shift (0.8), and (iii) a small red shift (0.2), respectively. Thus, the blue shift and the red shift components were attributed to localized excitations on B850a and B850b, respectively. The B850a excitation decayed rapidly (∼ 0.1 ps), whereas the B850b excitation decayed more slowly (∼ 0.4 ps) and then stayed; the former decay was ascribed to singlet−singlet annihilation between B850a and B850b, whereas the latter decay to singlet−singlet annihilation between B850b's. The unique feature of excitation with high photon density, which preferentially generates the localized excitations through multiple excitation, and enhances subsequent singlet−singlet annihilation reactions, is discussed.

Published
2001
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19. Simulation of X-ray powder diffraction

Author

Qian Pu

Subjects
Crystallography, Computer based learning, Materials science, X-ray crystallography, X-ray, General Chemistry, Powder diffraction, Education
Abstract

142. Bits and pieces, 48. A program that simulates the entire procedure of the analysis of X-ray powder diffraction.

Published
1992
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20. Simulation of the infrared spectrum of HCl

Author

Qian Pu

Subjects
Computer based learning, Materials science, Computer program, Infrared, Thermal infrared spectroscopy, Analytical chemistry, Infrared spectroscopy, General Chemistry, Education
Abstract

121. Bits and pieces, 45. A computer program that helps students master the method and technique of infrared measurements of HCl, even if they have no spectrophotometer.

Published
1990
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