Achiral diacetylene 10,12-pentacosadinoic acid (PCDA) and a chiral low-molecular-weight organogelator could form co-gel in organic solvent and it could be polymerized in the presence of Zn(II) ion or in the correspond...Achiral diacetylene 10,12-pentacosadinoic acid (PCDA) and a chiral low-molecular-weight organogelator could form co-gel in organic solvent and it could be polymerized in the presence of Zn(II) ion or in the corresponding xerogel under UV-irradiation. Optically active polydiacetylene (PDA) were subsequently obtained. Supramolecular chirality of PDA could be controlled by the chirality of gelators. Left-handed and right-handed helical fibers were obtained by using Land D-gelators in xerogels respectively, and CD spectra exhibited mirror-image circular dichroism. The PDA in xerogel exhibited typical blue-to-red transition responsive to the temperature and pH, while the supramolecular chirality of PDA showed a corresponding change.展开更多
This paper studies the electromagnetic response of a coherently driven dense atomic ensemble to a weak probe. It finds that negative refraction with little absorption may be achieved in the presence of local-field enh...This paper studies the electromagnetic response of a coherently driven dense atomic ensemble to a weak probe. It finds that negative refraction with little absorption may be achieved in the presence of local-field enhanced interaction and dynamically induced chirality. The complex refractive index governing the probe refraction and absorption depends critically on the atomic density, the steady population distribution, the coherence dephasings, and the frequency de- tunings, and is also sensitive to the phase of the driving field because the photonic transition paths form a close loop. Thus, it can periodically tune the refractive index at a fixed frequency from negative to positive values and vice versa just by modulating the driving phase. Moreover, the optimal negative refraction is found to be near the probe magnetic resonance, which then requires the electric fields of the probe and the drive being on two-photon resonance due to the dipole synchronisation.展开更多
The phase transition behavior and aggregating states of [smectic LCP, PS(4BC/DM)/nematic LC, E7/chiral dopant, CB 15] ternary composite system were investigated on the basis of differential scanning calorimetry (DSC)...The phase transition behavior and aggregating states of [smectic LCP, PS(4BC/DM)/nematic LC, E7/chiral dopant, CB 15] ternary composite system were investigated on the basis of differential scanning calorimetry (DSC) measurement, polarizing optical microscopy (POM) observation and wide angle X ray diffraction (WAXD) patterns. It was demonstrated that if the weight ratio of the chiral dopant was fixed as 4.8wt%, an induced chiral nematic (N *) phase existed in the ternary system when PS(4BC/DM) ratio was below 47.6 wt%. Moreover, smectic like long range ordering appeared in the induced N * phase in a certain temperature range just above the smectic A(S A) N * phase transition when PS(4BC/DM) ratio was between 19.1wt% and 47.6wt%.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 50673095 and 20533050)973 Project (Grant No. 2007CB808005)
文摘Achiral diacetylene 10,12-pentacosadinoic acid (PCDA) and a chiral low-molecular-weight organogelator could form co-gel in organic solvent and it could be polymerized in the presence of Zn(II) ion or in the corresponding xerogel under UV-irradiation. Optically active polydiacetylene (PDA) were subsequently obtained. Supramolecular chirality of PDA could be controlled by the chirality of gelators. Left-handed and right-handed helical fibers were obtained by using Land D-gelators in xerogels respectively, and CD spectra exhibited mirror-image circular dichroism. The PDA in xerogel exhibited typical blue-to-red transition responsive to the temperature and pH, while the supramolecular chirality of PDA showed a corresponding change.
基金supported by the National Natural Science Foundation of China (Grant No. 10874057)
文摘This paper studies the electromagnetic response of a coherently driven dense atomic ensemble to a weak probe. It finds that negative refraction with little absorption may be achieved in the presence of local-field enhanced interaction and dynamically induced chirality. The complex refractive index governing the probe refraction and absorption depends critically on the atomic density, the steady population distribution, the coherence dephasings, and the frequency de- tunings, and is also sensitive to the phase of the driving field because the photonic transition paths form a close loop. Thus, it can periodically tune the refractive index at a fixed frequency from negative to positive values and vice versa just by modulating the driving phase. Moreover, the optimal negative refraction is found to be near the probe magnetic resonance, which then requires the electric fields of the probe and the drive being on two-photon resonance due to the dipole synchronisation.
文摘The phase transition behavior and aggregating states of [smectic LCP, PS(4BC/DM)/nematic LC, E7/chiral dopant, CB 15] ternary composite system were investigated on the basis of differential scanning calorimetry (DSC) measurement, polarizing optical microscopy (POM) observation and wide angle X ray diffraction (WAXD) patterns. It was demonstrated that if the weight ratio of the chiral dopant was fixed as 4.8wt%, an induced chiral nematic (N *) phase existed in the ternary system when PS(4BC/DM) ratio was below 47.6 wt%. Moreover, smectic like long range ordering appeared in the induced N * phase in a certain temperature range just above the smectic A(S A) N * phase transition when PS(4BC/DM) ratio was between 19.1wt% and 47.6wt%.
