Browsing by Author "Wang, Ying"

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Circa conservation of vibrational energy among three strongly coupled modes of a cyanine dye molecule studied by quantum-beat spectroscopy with a 7 fs laser
(2008-11-24)
Kobayashi, Takayoshi
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Wang, Ying
;
Wang, Zhuan
;
Iwakura, Izumi
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電子物理學系
Real-time energy exchange among the three vibrational modes forming a triplet with frequencies omega(1), omega(2), and omega(3) satisfying a 'circa sum-frequency relation', namely omega(1) + omega(2) congruent to omega(3) in a cyanine dye molecule has been studied with a 7-fs pulse laser. There are two triplets with average frequencies of the components of (146, 279, 432 cm (1)) and (279, 432, 738 cm (1)). Even though the circa sum-frequency relation is satisfied, circa- conservation of the vibrational energy holds among the three components only in the latter triplet. The difference between the two is ascribed to the symmetry of the molecular vibrational modes. (C) 2008 Elsevier B. V. All rights reserved.
Electronic and Vibrational Coherence Dynamics in a Cyanine Dye Studied Using a Few-Cycle Pulsed Laser
(2010-03-05)
Wang, Ying
;
Kobayashi, Takayoshi
;
電子物理學系
;
Department of Electrophysics
We report the relaxation times of electronic and vibrational coherence in the cyanine dye 1,1',3,3,3',3'-hexamethyl-4,4',5,5'-dibenzo-2,2'-indotricarbocyanine, measured using a 7.1 fs pulsed laser. The vibrational phase relaxation times are found to be between 380 and 680 fs in the ground and lowest excited singlet states. The vibrational dephasing times of the 294, 446, and 736 cm(-1) modes are relatively long among the six modes associated with excited-state wave packets. The slower relaxations are explained in terms of a coupled triplet of vibrational modes, which preserves coherence by forming a tightly bound group to satisfy the condition of circa conservation of vibrational energy. Using data from the negative-time range (i.e., when the probe pulse precedes the pump pulse), the electronic phase relaxation time is found to be 31 +/- 1 fs. The dynamic vibrational mode in the excited state (1171 cm(-1)), detected in the positive-time range, is also studied from the negative-time traces under the same experimental conditions.
LWD-TCP complex activates the morning gene CCA1 in Arabidopsis
(2016-10-13)
Wu, Jing-Fen
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Tsai, Huang-Lung
;
Joanito, Ignasius
;
Wu, Yi-Chen
;
Chang, Chin-Wen
A double-negative feedback loop formed by the morning genes CIRCADIAN CLOCK ASSOCIATED1 (CCA1)/LATE ELONGATED HYPOCOTYL (LHY) and the evening gene TIMING OF CAB EXPRESSION1 (TOC1) contributes to regulation of the circadian clock in Arabidopsis. A 24-h circadian cycle starts with the peak expression of CCA1 at dawn. Although CCA1 is targeted by multiple transcriptional repressors, including PSEUDO-RESPONSE REGULATOR9 (PRR9), PRR7, PRR5 and CCA1 HIKING EXPEDITION (CHE), activators of CCA1 remain elusive. Here we use mathematical modelling to infer a co-activator role for LIGHT-REGULATED WD1 (LWD1) in CCA1 expression. We show that the TEOSINTE BRANCHED 1-CYCLOIDEA-PCF20 (TCP20) and TCP22 proteins act as LWD-interacting transcriptional activators. The concomitant binding of LWD1 and TCP20/TCP22 to the TCP-binding site in the CCA1 promoter activates CCA1. Our study reveals activators of the morning gene CCA1 and provides an action mechanism that ensures elevated expression of CCA1 at dawn to sustain a robust clock.