The analytic response theory at density functional theory level is applied to investigate onephoton and two-photon absorption properties of a series of recently synthesized pyrene-core derivatives. The theoretical res...The analytic response theory at density functional theory level is applied to investigate onephoton and two-photon absorption properties of a series of recently synthesized pyrene-core derivatives. The theoretical results show that there are a few charge-transfer states for each compound in the lower energy region. The one-photon absorption properties of the five investigated compounds are highly consistent with those given by experimental measurements. The two-photon absorption intensities of the compounds are greatly enhanced with the increments of the molecular sizes, in which the two-photon absorption cross section of the four-branched compound is about 5.6 times of that of the mono-branched molecule. Fhrthermore, it is shown that the two-photon absorption properties are sensitive to the geometrical arrangements.展开更多
We discuss and analyze the absorption-amplification properties of a weak probe field in a typical four-level atomic system in the presence of an additional coherence term, the spontaneously generated coherence term. T...We discuss and analyze the absorption-amplification properties of a weak probe field in a typical four-level atomic system in the presence of an additional coherence term, the spontaneously generated coherence term. Theinfluences of the spontaneously generated coherence and a coherent pump field on the probe absorption (amplification)are investigated in detail. We show that the absorption of such a weak probe field can be dramatically enhanced dueto the presence of the spontaneously generated coherence. At the same time, the probe-absorption profile exhibitsthe double-peak structure and the probe-absorption peak gradually decreases as the pump intensity increases. On thecontrary, the amplification of such a weak probe field near the line center of the probe transition can be achieved byadjusting the coherent pump field intensity in the absence of the spontaneously generated coherence.展开更多
Infrared absorption spectra of gaseous CH2Cl2 in the regions of 1200-12000 cm^-1 were measured using a Bruker IFS 120HR Fourier transform spectrometer in conjunction with a nmltipass cell. 47 vibrational levels of ove...Infrared absorption spectra of gaseous CH2Cl2 in the regions of 1200-12000 cm^-1 were measured using a Bruker IFS 120HR Fourier transform spectrometer in conjunction with a nmltipass cell. 47 vibrational levels of overtone and combinational spectral lines of the CH stretching （v1, v6）, bending （v2）, and rocking （v8） modes were analyzed and assigned. Utilizing the normal mode model and considering the coupling among CH stretching, bending and rocking vibrations, values of the harmonic frequency wi, the anharmonic constant xij, and the coefficients of Fermi and the Darling-Dennison resonances of v1, v6, v2 and v8 modes were also determined from experimental spectral data with nonlinear least-square fitting. These spectral constants reproduced the experimental levels very well. These results showed that Fermi resonance between CH stretching and rocking vibrations （kiss=-254.63 cm^-1） is stronger than that between CH stretching and bending vibrations （k122 = 54.87 cm^-1 ）; and that Darling-Dennison resonances between CH stretching and bending vibrations （k166=-215.28 cm^-1） is also much stronger than that between CH bending and rocking vibrations （k2288=5.72 cm^-1）.展开更多
Flexible photodetectors(PDs) have huge potential for application in next-generation optoelectronic devices due to their lightweight design, portability, and excellent large area compatibility. The main challenge in th...Flexible photodetectors(PDs) have huge potential for application in next-generation optoelectronic devices due to their lightweight design, portability, and excellent large area compatibility. The main challenge in the construction of flexible PDs is to maintain the optoelectronic performance during repetitive bending, folding and stretching.Herein, flexible PDs based on ZnO nanowires(NWs) and CsPbBr3 nanosheets(NSs) were constructed by an integrated low-dimensional structure strategy. Benefiting from the flexibility of unique sheet and wire structures, the PDs were able to maintain excellent operational stability under various mechanical stresses. For example, the PDs exhibited no obvious changes in optoelectronic performance after bending for 1000 times. Additionally, the PDs exhibited an integrated broadband response ranging from ultraviolet to visible region due to the combination of the intrinsic light absorption capability of ZnO and CsPbBr3. The PDs demonstrated high responsivities of 3.10 and 0.97 A W^-1 and detectivities of 5.57×10^12 and1.71×10^12 Jones under ultraviolet and visible light irradiation,respectively. The proposed construction strategy for highly flexible and performance-integrated PDs shows great potential in future smart, wearable optoelectronic devices.展开更多
文摘The analytic response theory at density functional theory level is applied to investigate onephoton and two-photon absorption properties of a series of recently synthesized pyrene-core derivatives. The theoretical results show that there are a few charge-transfer states for each compound in the lower energy region. The one-photon absorption properties of the five investigated compounds are highly consistent with those given by experimental measurements. The two-photon absorption intensities of the compounds are greatly enhanced with the increments of the molecular sizes, in which the two-photon absorption cross section of the four-branched compound is about 5.6 times of that of the mono-branched molecule. Fhrthermore, it is shown that the two-photon absorption properties are sensitive to the geometrical arrangements.
文摘We discuss and analyze the absorption-amplification properties of a weak probe field in a typical four-level atomic system in the presence of an additional coherence term, the spontaneously generated coherence term. Theinfluences of the spontaneously generated coherence and a coherent pump field on the probe absorption (amplification)are investigated in detail. We show that the absorption of such a weak probe field can be dramatically enhanced dueto the presence of the spontaneously generated coherence. At the same time, the probe-absorption profile exhibitsthe double-peak structure and the probe-absorption peak gradually decreases as the pump intensity increases. On thecontrary, the amplification of such a weak probe field near the line center of the probe transition can be achieved byadjusting the coherent pump field intensity in the absence of the spontaneously generated coherence.
基金This work was supported by National Natural Science Foundation of China （Grant No. 10274077, 20103007 and 29703007）. The authors would like to thank Wei Chu, Yong-qiang Xu and Guo-sheng Cheng for their kind help.
文摘Infrared absorption spectra of gaseous CH2Cl2 in the regions of 1200-12000 cm^-1 were measured using a Bruker IFS 120HR Fourier transform spectrometer in conjunction with a nmltipass cell. 47 vibrational levels of overtone and combinational spectral lines of the CH stretching （v1, v6）, bending （v2）, and rocking （v8） modes were analyzed and assigned. Utilizing the normal mode model and considering the coupling among CH stretching, bending and rocking vibrations, values of the harmonic frequency wi, the anharmonic constant xij, and the coefficients of Fermi and the Darling-Dennison resonances of v1, v6, v2 and v8 modes were also determined from experimental spectral data with nonlinear least-square fitting. These spectral constants reproduced the experimental levels very well. These results showed that Fermi resonance between CH stretching and rocking vibrations （kiss=-254.63 cm^-1） is stronger than that between CH stretching and bending vibrations （k122 = 54.87 cm^-1 ）; and that Darling-Dennison resonances between CH stretching and bending vibrations （k166=-215.28 cm^-1） is also much stronger than that between CH bending and rocking vibrations （k2288=5.72 cm^-1）.
基金financially supported by the National Natural Science Foundation of China (51672132 and 61604074)the Natural Science Foundation of Jiangsu Province (BK20160827 and BK20180020)+3 种基金China Postdoctoral Science Foundation (2016M590455)Open foundation of Key Laboratory of Marine Materials and Related Technologies (2016K08)the Fundamental Research Funds for the Central Universities (30917011202)PAPD of Jiangsu Higher Education Institutions
文摘Flexible photodetectors(PDs) have huge potential for application in next-generation optoelectronic devices due to their lightweight design, portability, and excellent large area compatibility. The main challenge in the construction of flexible PDs is to maintain the optoelectronic performance during repetitive bending, folding and stretching.Herein, flexible PDs based on ZnO nanowires(NWs) and CsPbBr3 nanosheets(NSs) were constructed by an integrated low-dimensional structure strategy. Benefiting from the flexibility of unique sheet and wire structures, the PDs were able to maintain excellent operational stability under various mechanical stresses. For example, the PDs exhibited no obvious changes in optoelectronic performance after bending for 1000 times. Additionally, the PDs exhibited an integrated broadband response ranging from ultraviolet to visible region due to the combination of the intrinsic light absorption capability of ZnO and CsPbBr3. The PDs demonstrated high responsivities of 3.10 and 0.97 A W^-1 and detectivities of 5.57×10^12 and1.71×10^12 Jones under ultraviolet and visible light irradiation,respectively. The proposed construction strategy for highly flexible and performance-integrated PDs shows great potential in future smart, wearable optoelectronic devices.
