- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Aggregation-induced emission (AIE)-active molecules bearing singlet oxygen generation activities: the tunable singlet–triplet energy gap matters
摘要： Herein, a series of photosensitizers were constructed of a, b and c-isomers of terpyridine and the corresponding N-methylation derivatives. Benefiting from the tunable singlet–triplet energy gap and aggregation-induced emission characteristics, two-photon active photosensitizers L2b and L2c showed relatively strong intersystem crossing facilitating 1O2 generation and cell apoptosis with near-infrared excitation.
关键词： Aggregation-induced emission,singlet oxygen generation,photodynamic therapy,photosensitizers,two-photon excitation
更新于2025-09-19 17:15:36
-
On the photo-activation of the S <sub/>0</sub> ?→?S <sub/>1</sub> transition in polyenes
摘要： The evidence provided in this work allows us to conclude that the electronic transition S0 → S1 either for the diphenylhexatriene molecule or for the diphenyloctatetraene molecule is dipole allowed and induced by one‐photon absorption. Consequently, the model to explain the photophysics of these polyenes does not need the existence of an underlying 21Ag excited electronic state, to the converse of what Hudson and Kohler proposed, that the transition S0 → S1 must be induced by two‐photon absorption.
关键词： two‐photon absorption,excitation spectra,photophysics of polyenes
更新于2025-09-19 17:15:36
-
Ultrashort laser based two-photon phase-resolved fluorescence lifetime measurement method
摘要： This paper presents a two-photon phase-resolved fluorescence-lifetime measurement method based on the use of an ultrashort pulse laser. The proposed method also involves the use of a lock-in amplifier to control the phase difference between the reference and fluorescence signals, thereby facilitating the use of an alternative method for determining fluorescence lifetimes. Verification of the fluorescence lifetimes as measured in this study was performed using rhodamine B and a cellular thermoprobe as samples. In this study, we assume that the fluorescence decay was monoexponential in all cases. Rhodamine B was observed to exhibit an average fluorescence lifetime of 2.15 ns, whereas a temperature sensitivity of 1.39 ns/°C over a temperature range of 33.79–37.2 °C was demonstrated for the cellular thermoprobe. These results validate the feasibility of the proposed method for accurate measurement of fluorescence lifetimes using a simple laser configuration.
关键词： rhodamine B,ultrashort pulse laser,temperature sensor,phase-resolved fluorescence-lifetime,two-photon microscopy,cellular thermoprobe
更新于2025-09-19 17:13:59
-
Mechanism of stimulated Mie scattering: Light-induced redistribution of self-assembled nanospheres of two-photon absorbing chromophore
摘要： We report the observation of backward stimulated Mie scattering (SMS) due to light-field induced spatial redistribution of self-assembled nanospheres of a two-photon resonant organic chromophore in water, pumped by ～10-ns laser pulses of ～816-nm wavelength. The pump-energy threshold for generating backward stimulated scattering in such a system is remarkably lower than that in pure water. The gain of backscattering originates from an induced Bragg grating that reflects partial energy from the pump beam into the backward Mie scattering beam. Based on the experimental fact that the time-delay of the SMS pulse onset depends on both the pump level and the viscosity of the solvent, a physical model of SMS generation is proposed. Our experimental results have shown that the major contribution to the formation of an induced Bragg grating is spatial redistribution of nanoparticles suspended in the liquid. These nanoparticles are driven by a force that is proportional to the intensity gradient of the standing-wave field resulting from interference between the forward pump beam and the backward Mie scattering beam. When the nanoparticle motion is frozen in a gel-like medium, no SMS is observed, which experimentally supports the validity of the proposed physical model.
关键词： two-photon absorbing chromophore,stimulated Mie scattering,nanospheres,light-induced redistribution,Bragg grating
更新于2025-09-19 17:13:59
-
Visualization of carboxylesterase 2 with a near-infrared two-photon fluorescent probe and its potential evaluation of anticancer drug effects in orthotopic colon carcinoma mice model
摘要： We establish a near-infrared two-photon fluorescent probe for the detection of CE2 with high selectivity and sensitivity. This probe exhibits low cytotoxicity and superior tissue penetration ability for evaluating real-time activity of CE2 in living cells, in cancer tissues, and in colon carcinoma mice model.
关键词： anticancer drug effects,colon carcinoma,CE2,fluorescent probe,two-photon,near-infrared
更新于2025-09-19 17:13:59
-
Enhanced Small-Signal Responsivity in Silicon Microring Photodetector Based on Two-Photon Absorption
摘要： We experimentally investigated methods of enhancing the small-signal responsivity of a silicon pin microring photodetector based on two-photon absorption for detecting small optical signals in the telecommunication wavelength range. Two approaches are demonstrated, the first exploiting the bistability effect in the nonlinear microring resonator while the second employing an optical bias at a different wavelength to increase the differential responsivity. We achieved a small-signal responsivity of 180 mA/W with the first approach and 141 mA/W with the second approach, both of which represent almost 10-fold enhancement over direct detection of small optical signals by the same silicon pin microring detector. Our techniques have potential applications in amplitude demodulation, heterodyne detection, and optical power monitoring in WDM communication channels.
关键词： microring resonator,photodetector,two-photon absorption,Silicon photonics
更新于2025-09-19 17:13:59
-
[IEEE 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Zatoka, Ukraine (2018.9.9-2018.9.14)] 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Efficient Two-Photon Luminescence for Bioimaging Using Polymer Conjugations of Graphene Quantum Dots Based Materials
摘要： In this study, examination results revealed that conjugated polymers containing nitrogen and sulfur atoms lead to a higher quantum confinement of emissive energy trapped on the surface of material (graphene quantum dot (GQD)-polymers), resulting in a high luminescence quantum yield and impressive two-photon properties. Additionally, the GQD-polymers generated nonreactive oxygen species-dependent oxidative stress on cells. Furthermore, we demonstrated the effective use of two-photon excitation-mediated high two-photon luminescence intensity in an acidic environment enabled GQD-polymers to act as a promising contrast probe. When cancer cells are labeled with specific antibody GQD-polymers conjugates, molecular-specific imaging can be performed deep into a tissue phantom with extremely high signal-to-noise ratios. In situations in which imaging depths are limited by the maximum available power that can be delivered to the three-dimensional (3D) bioimaging plane without causing damage to tissue, GQD-polymers might provide sufficient brightness to extend the maximum depth of imaging. Moreover, we demonstrated that the use of GQD-polymers can expand the capabilities of two-photon imaging to allow noninvasive 3D bioimaging of a variety of new molecular signatures.
关键词： photostability,reactive oxygen species,three-dimensional bioimaging,photodynamic therapy,two-photon excitation,contrast probe,graphene,quantum dot-polymer,two-photon luminescence,two-photon,contrast agent,nitrogen-doped graphene quantum dots
更新于2025-09-16 10:30:52
-
Sensitive Infrared Photon Counting Detection by Nondegenerate Two-Photon Absorption in Si APD
摘要： We report on the sensitive detection of photons at broadband infrared wavelengths based on the nondegenerate two-photon absorption in the Si avalanche photodiodes. The detected 1700~1850 nm infrared photon energy is lower than Si band gap and the energy difference is complemented by a high intensity pump laser field at 1550 nm. It is thus possible to capitalize on the low noise property of large band gap materials for detecting low energy photons. And the linear intensity response of the detector to the incident infrared photons was observed when the power of pump laser was about 12.42 μW, indicating the dominance of nondegenerate two-photon absorption in the infrared photon detection. An enhancement factor of 20 was observed for the incident signal photon numbers of ~0.14×106 photons per pulse. We offer an alternative to sensitive detection of infrared light. This may also provide new ideas for broadband infrared photon detection in different applications such as optical comb laser ranging, infrared bio-image and so forth.
关键词： Infrared photon detection,silicon avalanche photodiode,nondegenerate two photon absorption
更新于2025-09-16 10:30:52
-
[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - High-Responsivity Silicon Microring Photodetector Based on Two-Photon Absorption
摘要： We report a silicon pin microring photodetector based on two-photon absorption with responsivity enhanced by optical resonance and optical biasing. A small-signal responsivity of 100mA/W was achieved, which is the highest reported TPA-based silicon photodetectors.
关键词： microring resonator,silicon photonics,photodetector,two-photon absorption
更新于2025-09-16 10:30:52
-
High-order harmonic generation from diatomic molecules in an orthogonally polarized two-color laser field
摘要： In this study, a two photon absorbing (TPA) material consisting silver nanoparticles and triphenylamine-thiol derivative (TBS) has been prepared through interfacial coordination effect according to soft-hard-acid-base principle. The interfacial structure and morphology of the hybrid are researched in detail. Linear and nonlinear optical properties of the hybrid are studied. Upon interfacial coordination, the hybrid shows red-shifted UV–Vis absorption, causing from enhanced electronic drawing strength due to existence of Ag atom. The results also indicate that the surface Plasmon resonance (SPR) effect of Ag nanoparticles (~6 nm) brings about enhancement in single photon fluorescence emission and two photon absorption. Compared with free TBS, Ag-TBS hybrids show higher TPA cross-section (δ), which is 8784 GM for TBS and up to 103876 GM for Ag-TBS hybrid, showing ~12 fold increase. Due to excellent TPA property, the hybrids have good application in the field of optical power limiting and its limiting threshold is 0.49 J/cm?2. This type of interfacial coordination induced hybrid provides a promising strategy to regulate linear optical properties and optimize nonlinear performance.
关键词： Surface plasmon resonance,Interfacial coordination,Optical power limiting,Two photon absorption
更新于2025-09-16 10:30:52