- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Quantumness in light harvesting is determined by vibrational dynamics
摘要： We demonstrate for the multi-level spin-boson (MLSB) Hamiltonian, typically used to describe biological light-harvesting, that the distinction between quantum and classical dynamics is determined entirely by the thermal environment. In particular, any MLSB model featuring classical interactions with a classical bath is exactly equivalent in its absorption and energy transfer dynamics to a classical model involving coupled harmonic oscillators. This result holds in the linear response regime for both pulsed and incoherent excitation. In the biological context, this finding highlights the centrality of vibrational dynamics in determining the 'quantumness' of photosynthetic light-harvesting, particularly in the creation of the photosynthetic energy funnel where excitation energy concentrates near the reaction center via a series of downhill energy transfer events. These findings support the idea that this energy funnel is exclusively quantum-mechanical in origin, although it need not rely on entanglement.
关键词： vibrational dynamics,energy transfer,photosynthesis,quantumness,light harvesting,spin-boson model
更新于2025-09-23 15:23:52
-
Hidden Isolated OH at the Charged Hydrophobic Interface Revealed by Two-Dimensional Heterodyne-Detected VSFG Spectroscopy
摘要： Water around hydrophobic groups mediates hydrophobic interactions that play key roles in many chemical and biological processes. Thus, the molecular-level elucidation of the properties of water in the vicinity of hydrophobic groups is important. We report on the structure and dynamics of water at two oppositely charged hydrophobic ion/water interfaces, the tetraphenylborate-ion (TPB?)/water and tetraphenylarsonium-ion (TPA+)/water interfaces, which are clarified by two-dimensional heterodyne-detected vibrational sum-frequency generation (2D HD-VSFG) spectroscopy. The obtained 2D HD-VSFG spectra of the anionic TPB? interface reveal the existence of distinct π-hydrogen bonded OH groups in addition to the usual hydrogen-bonded OH groups, which are hidden in the steady-state spectrum. In contrast, 2D HD-VSFG spectra of the cationic TPA+ interface only show the presence of usual hydrogen-bonded OH groups. The present study demonstrates that the sign of the interfacial charge governs the structure and dynamics of water molecules that face the hydrophobic region.
关键词： hydrophobic interfaces,sum-frequency generation,ultrafast spectroscopy,interfacial water,vibrational dynamics
更新于2025-09-23 15:21:01
-
Hidden isolated OH at the charged hydrophobic interface revealed by two-dimensional heterodyne-detected VSFG spectroscopy
摘要： Water around the hydrophobic groups mediates hydrophobic interaction that plays key roles in many chemical and biological processes. Thus, molecular-level elucidation of the properties of the water in the vicinity of the hydrophobic group is important. We report on the structure and dynamics of water at two oppositely charged hydrophobic interfaces, i.e., the tetraphenylborate ion (TPB-)/water and tetraphenylarsonium ion (TPA+)/water interfaces, which are clarified by two-dimensional heterodyne-detected vibrational sum frequency generation (2D HD-VSFG) spectroscopy. The obtained 2D HD-VSFG spectra of anionic TPB- interface reveal the existence of distinct π-hydrogen bonded OH groups in addition to the usual hydrogen bonded OH groups, which is hidden in the steady-state spectrum. In contrast, 2D HD-VSFG spectra of cationic TPA+ interface only show the presence of usual hydrogen bonded OH groups. The present study demonstrates that the sign of the interfacial charge governs the structure and dynamics of water molecules that face the hydrophobic region.
关键词： sum-frequency generation,ultrafast spectroscopy,hydrophobic interfaces,interfacial water,vibrational dynamics
更新于2025-09-23 15:19:57
-
Heterogeneous Cationa??Lattice Interaction and Dynamics in Triple-Cation Perovskites Revealed by Infrared Vibrational Nanoscopy
摘要： Hybrid organic-inorganic perovskites exhibit extraordinary photovoltaic performance. This is believed to arise from almost liquid-like low-energy interactions among lattice ions and charge carriers. While spatial variations have recently been identified over multiple length scales in the optoelectronic responses, the relationship of the heterogeneity and the soft cation-lattice interactions has remained elusive. Here, we apply multivariate infrared vibrational nano-imaging to a formamidinium (FA)-methylammonium (MA)-cesium triple cation perovskite. By using the FA vibrational resonance as a probe of its local chemical environment, through spatial variation and correlation in composition, strength of cation-lattice coupling and its associated few-ps vibrational dynamics, we reveal how a varying local reaction field is correlated with the cation-lattice coupling. We attribute the associated heterogeneous lattice contraction to a non-uniform distribution of cesium cations. The observed varying elasticity of the lattice leads to disordered charge-phonon coupling and polaron formation, the control of which is central to improving perovskite photovoltaics.
关键词： charge-phonon coupling,infrared vibrational nano-imaging,Hybrid organic-inorganic perovskites,lattice contraction,photovoltaic performance,cation-lattice coupling,polaron formation,vibrational dynamics
更新于2025-09-19 17:13:59
-
Ultrafast vibrational coupling between C H and C O band of cyclic amide 2-Pyrrolidinone revealed by 2DIR spectroscopy
摘要： Coupling between C–H and C=O vibrational modes play an essential role on determination of biological structure and dynamics. However, due to the weakness of the C–H absorption and strong absorption of the C=O vibrational band make such experiments less straightforward than those with transitions of nearly the same strength. In this communication the characteristics of the C–H and C=O coupling has been studied using dual frequency two dimensional infrared spectroscopy. 2-Pyrrolidinone has been used as a model molecule of biological system. The coherent and incoherent couplings between C–H and C=O vibrational bands have been observed. The cross peaks dynamics have been discussed and time constant of the cross peak intensity has been calculated.
关键词： dual frequency,vibrational coupling,vibrational spectroscopy,Molecular structure,2DIR spectroscopy,vibrational dynamics
更新于2025-09-12 10:27:22
-
Vibrational Energy Redistribution between CH Stretching Modes in Alkyl Chain Monolayers Revealed by Time-Resolved Two-Color Pump–Probe Sum Frequency Spectroscopy
摘要： The vibrational dynamics of the various CH stretching modes in a fatty acid Langmuir?Blodgett ?lm was studied using a resonant narrowband infrared (IR) laser pulse for pumping and a broadband femtosecond IR visible pulse pair for detection in a sum frequency spectroscopy setup. The resulting two-dimensional spectra indicate that pumping either the antisymmetric methyl or methylene stretch results in the transfer of energy to the other modes on a time scale faster than 2 ps. This rapid process is followed by energy redistribution to other modes, presumably the bending and internal rotational modes, with a time constant of approximately 85 ps. The formation of gauche defects is not observed within the ?rst 250 ps. The whole spectrum recovers on a time scale of several nanoseconds, indicating dissipation of the excitation energy into the substrate.
关键词： CH stretching modes,energy redistribution,vibrational dynamics,sum frequency spectroscopy,Langmuir?Blodgett ?lm
更新于2025-09-12 10:27:22
-
Direct excitation of molecular vibrational motion by intense broadband THz pulses
摘要： We theoretically investigate molecular vibrational dynamics driven by intense and broadband THz pulses. The light-nuclei interaction is derived from a fully quantum-mechanical minimal coupling Hamiltonian to analyse direct excitation of vibrational modes by the THz pulses. We show that for diatomic molecules a "vibrational moment" can be defined in a manner similar to the dipole moment and that it has non-zero values only for heteronuclear diatomic molecules. Taking ultra-cold heteronuclear diatomic molecules as examples, we show that vibrational-mode excitation by THz pulse irradiation occurs almost stepwisely, especially for low vibrational modes. Coherent control method using frequency-controlled THz pulse sequence is also proposed.
关键词： quantum-mechanical minimal coupling Hamiltonian,vibrational moment,heteronuclear diatomic molecules,coherent control,molecular vibrational dynamics,THz pulses
更新于2025-09-09 09:28:46