Abstract:Chemical reaction and optical dynamics in the liquid phase are strongly affected by specific solute-solvent interactions. The dynamical part of this coupling leads to energy fluctuations. The associated energy gap dynamics can be probed by using various nonlinear optical spectroscopies. We discuss various forms of photon echo--time-integrated, time-gated, and heterodyne-detected photon echo--as well as Fourier transform spectral interferometry. It is shown that for solutions of the dye molecule DTTCI, a system… Show more
“…It was shown 7,45,46 that a good estimate for the decay of M(t) can be obtained from three-pulse photon echo peak shift (3PEPS) measurements. Here the sample is irradiated by a sequence of three identical resonant pulses and the time integrated photon echo signal is recorded as a function of both interpulse delays, t 12 and t 23 .…”
Broadband transient absorption (TA) spectroscopy, three-pulse photon echo peak shift (3PEPS), and anisotropy decay measurements were used to study the solvation dynamics in bulk water and interfacial water at ZrO 2 surfaces, using Eosin Y as a probe. The 3PEPS results show a multiexponential behavior with two subpicosecond components that are similar in bulk and interfacial water, while a third component of several picoseconds is significantly lengthened at the interface. The bandwidth correlation function from TA spectra exhibits the same behavior, and the TA spectra are well reproduced using the doorway-window picture with the time constants from PEPS. Our results suggest that interfacial water is restricted to a thickness of less than 5 Å. Also the high-frequency collective dynamics of water does not seem to be affected by the interface. On the other hand, the increase of the third component may point to a slowing down of diffusional motion at the interface, although other effects, may play a role, which are discussed.
“…It was shown 7,45,46 that a good estimate for the decay of M(t) can be obtained from three-pulse photon echo peak shift (3PEPS) measurements. Here the sample is irradiated by a sequence of three identical resonant pulses and the time integrated photon echo signal is recorded as a function of both interpulse delays, t 12 and t 23 .…”
Broadband transient absorption (TA) spectroscopy, three-pulse photon echo peak shift (3PEPS), and anisotropy decay measurements were used to study the solvation dynamics in bulk water and interfacial water at ZrO 2 surfaces, using Eosin Y as a probe. The 3PEPS results show a multiexponential behavior with two subpicosecond components that are similar in bulk and interfacial water, while a third component of several picoseconds is significantly lengthened at the interface. The bandwidth correlation function from TA spectra exhibits the same behavior, and the TA spectra are well reproduced using the doorway-window picture with the time constants from PEPS. Our results suggest that interfacial water is restricted to a thickness of less than 5 Å. Also the high-frequency collective dynamics of water does not seem to be affected by the interface. On the other hand, the increase of the third component may point to a slowing down of diffusional motion at the interface, although other effects, may play a role, which are discussed.
“…[1][2] With the advent of reliable and stable femtosecond laser systems ultrafast time resolved techniques have been developed to unravel such information. Among those techniques, a powerful method known as two-dimensional electronic spectroscopy (2D ES) has been developed to give direct and precise information about couplings in molecular electronic transitions and at the same time enabling determination of line broadening mechanisms.…”
In this work we present experimental and calculated two-dimensional electronic spectra for a 5,15-bisalkynyl porphyrin chromophore. The lowest energy electronic Q y transition couples mainly to a single 380 cm -1 vibrational mode. The two-dimensional electronic spectra reveal diagonal and cross peaks which oscillate as a function of population time. We analyse both the amplitude and phase distribution of this main vibronic transition as a function of excitation and detection frequencies.Even though Feynman diagrams provide a good indication of where the amplitude of the oscillating components are located in the excitation-detection plane, other factors also affect this distribution.Specifically, the oscillation corresponding to each Feynman diagram is expected to have a phase that is a function of excitation and detection frequencies. Therefore, the overall phase of the experimentally observed oscillation will reflect this phase dependence. Another consequence is that the overall oscillation amplitude can show interference patterns resulting from overlapping contributions from neighbouring Feynman diagrams. These observations are consistently reproduced through simulations based on third order perturbation theory coupled to a spectral density described by a Brownian oscillator model.
“…Some of the contributions of PE spectroscopy to solvation dynamics include: 30,31 (i) insights into the relationship between optical dynamics and solvation, (ii) the experimental determination of solute-solvent interactions (spectral density), (iii) fundamental solvation timescales, and (iv) the connection between various spectroscopic probes of solvation dynamics.…”
Section: Pe Spectroscopiesmentioning
confidence: 99%
“…500 fs ( More generally, solvation dynamics studies with PE spectroscopy have been performed with a variety of small polar solvents. 30,31,56 The broad picture revealed by this class of measurements is that, for small polar liquids, solvation dynamics occurs in a bimodal fashion with two characteristic time scales. The ultrafast component decays on a ca.…”
Section: Pe Spectroscopiesmentioning
confidence: 99%
“…In fact, a formal connection was established between TRFS and PE observables (solvation function and solvent equilibrium correlation function, respectively). 30,31 Taken together, the experimental and theoretical work enabled flexibility in the design of solvation dynamics experiments. For example, TRFS can be studied with commercially available instruments, and is generally considered to be simpler to implement.…”
A presença de moléculas de solvente na vizinhança de um soluto afeta uma variedade de processos em química e biologia, e por isso é interessante obter uma descrição física de como funciona a solvatação. Embora existam muitas ferramentas espectroscópicas estruturalmente sensíveis para a investigação do papel de moléculas de solvente em processos químicos, a medida em tempo real da dinâmica de solvatação somente tornou-se possível após o desenvolvimento de espectroscopias a laser pulsado com resolução temporal de femtossegundos. Esta revisão descreve aplicações da espectroscopia ultra-rápida ao estudo da dinâmica de solvatação. A nível de terceira ordem, discutimos a dinâmica de solvatação com técnicas ressonantes e não-ressonantes, com um foco no estudo de líquidos simples e complexos. Espectroscopias Raman de quinta ordem também são apresentadas, sendo que o enfoque dá-se no novo entendimento que estas técnicas fornecem com relação ao papel do solvente em reações químicas e à natureza anarmônica do estado líquido.The presence of solvent molecules in the vicinity of a solute affects a variety of processes in chemistry and biology, and thus one would like to have a physical picture of how solvation works. Although there are many structurally sensitive spectroscopic tools to investigate the role of solvent molecules in chemical processes, real time measurements of the dynamics of solvation had to wait for the development of pulsed laser spectroscopies with femtosecond time-resolution. This review describes applications of ultrafast spectroscopy to the study of solvation dynamics. At third order, we review resonant and non-resonant probes of solvation dynamics, with a focus on the study of simple and complex liquids. Fifth-order Raman spectroscopies are also reviewed, focusing on the insights these techniques give into the role of the solvent in chemical reactions and the anharmonic nature of the liquid state.
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