Vibrational spectroscopy, ultrafast

Cwrutsky J C, Li M, Culver J P, Sarisky M J, Yodh A G and Hoohstrasser R M 1993 Vibrational dynamios of oondensed phase moleoules studied by ultrafast infrared speotrosoopy Time Resolved Vibrational Spectroscopy VI (Springer Proc. in Physics 74) ed A Lau (New York Springer) pp 63-7... 

Stoner-Ma D, Melief EH, Nappa J et al (2006) Proton relay reaction in green fluorescent protein (GFP) polarization-resolved ultrafast vibrational spectroscopy of isotopically edited GFP. J Phys Chem B 110 22009-22018... 

Stoner-Ma D, laye AA, Matousek P, Towrie M, Meech SR, Tonge PJ (2005) Observation of excited-state proton transfer in green fluorescent protein using ultrafast vibrational spectroscopy. I Am Chem Soc 127 2864—2865... 

Vibrational spectroscopy can help us escape from this predicament due to the exquisite sensitivity of vibrational frequencies, particularly of the OH stretch, to local molecular environments. Thus, very roughly, one can think of the infrared or Raman spectrum of liquid water as reflecting the distribution of vibrational frequencies sampled by the ensemble of molecules, which reflects the distribution of local molecular environments. This picture is oversimplified, in part as a result of the phenomenon of motional narrowing The vibrational frequencies fluctuate in time (as local molecular environments rearrange), which causes the line shape to be narrower than the distribution of frequencies [3]. Thus in principle, in addition to information about liquid structure, one can obtain information about molecular dynamics from vibrational line shapes. In practice, however, it is often hard to extract this information. Recent and important advances in ultrafast vibrational spectroscopy provide much more useful methods for probing dynamic frequency fluctuations, a process often referred to as spectral diffusion. Ultrafast vibrational spectroscopy of water has also been used to probe molecular rotation and vibrational energy relaxation. The latter process, while fundamental and important, will not be discussed in this chapter, but instead will be covered in a separate review [4],... 

Bredenbeck J, Ghosh A, Nienhuys HK, Bonn M (2009) Interface-specific ultrafast two-dimensional vibrational spectroscopy. Acc Oiem Res 42 1332... 

Ultrafast vibrational spectroscopy offers a variety of techniques for unraveling the microsopic dynamics of hydrogen bonds occurring in the femto- to picosecond time domain. In particular, different vibrational couplings can be separated in nonlinear experiments by measuring vibrational dynamics in real-time. Both coherent vibrational polarizations and processes of population and energy relaxation have been studied for a number of hydrogen bonded systems in liquids [1],... 

When an electron is injected into a polar solvent such as water or alcohols, the electron is solvated and forms so-called the solvated electron. This solvated electron is considered the most basic anionic species in solutions and it has been extensively studied by variety of experimental and theoretical methods. Especially, the solvated electron in water (the hydrated electron) has been attracting much interest in wide fields because of its fundamental importance. It is well-known that the solvated electron in water exhibits a very broad absorption band peaked around 720 nm. This broad absorption is mainly attributed to the s- p transition of the electron in a solvent cavity. Recently, we measured picosecond time-resolved Raman scattering from water under the resonance condition with the s- p transition of the solvated electron, and found that strong transient Raman bands appeared in accordance with the generation of the solvated electron [1]. It was concluded that the observed transient Raman scattering was due to the water molecules that directly interact with the electron in the first solvation shell. Similar results were also obtained by a nanosecond Raman study [2]. This finding implies that we are now able to study the solvated electron by using vibrational spectroscopy. In this paper, we describe new information about the ultrafast dynamics of the solvated electron in water, which are obtained by time-resolved resonance Raman spectroscopy. 

Unlike the case of simple diatomic molecules, the reaction coordinate in polyatomic molecules does not simply correspond to the change of a particular chemical bond. Therefore, it is not yet clear for polyatomic molecules how the observed wavepacket motion is related to the reaction coordinate. Study of such a coherent vibration in ultrafast reacting system is expected to give us a clue to reveal its significance in chemical reactions. In this study, we employed two-color pump-probe spectroscopy with ultrashort pulses in the 10-fs regime, and investigated the coherent nuclear motion of solution-phase molecules that undergo photodissociation and intramolecular proton transfer in the excited state. 

Beyond imaging, CARS microscopy offers the possibility for spatially resolved vibrational spectroscopy [16], providing a wealth of chemical and physical structure information of molecular specimens inside a sub-femtoliter probe volume. As such, multiplex CARS microspectroscopy allows the chemical identification of molecules on the basis of their characteristic Raman spectra and the extraction of their physical properties, e.g., their thermodynamic state. In the time domain, time-resolved CARS microscopy allows recording of ultrafast Raman free induction decays (RFIDs). CARS correlation spectroscopy can probe three-dimensional diffusion dynamics with chemical selectivity. We next discuss the basic principles and exemplifying applications of the different CARS microspectroscopies. 

If ultrafast nonlinear vibrational spectroscopy [1-3] has recently developed into an important tool providing original informations on the dynamics of weak hydrogen bonds (H-bonds), the simpler linear infrared (IR) vs(X—H) absorption spectroscopy spectra remains, however, to be an important method for the understanding of this dynamics. Considerable experimental and theoretical works have been done in this last field [4—17]. 

Chudoba C, Nibbering ETJ, Elsaesser T. Dynamics of site-specific excited-state solute-solvent interactions as probed by femtosecond vibrational spectroscopy. In Elsaesser T, Fujimoto JG, Wiersma DA, Zinth W, eds. Ultrafast Phenomena XI. Berlin Springer-Verlag, 1998 535-537. 

The ultrafast infrared vibrational echo experiment and vibrational echo spectroscopy are powerful new techniques for the study of molecules and vibrational dynamics in condensed matter systems. In 1950, the advent of the NMR spin echo (1) was the first step on a road that has led to the incredibly diverse applications of NMR in many fields of science and medicine. Although vibrational spectroscopy has existed far longer than NMR, the experiments described here are the first ultrafast IR vibrational analogs of pulsed NMR methods. In the future, it is anticipated that the vibrational echo will be extended to an increasingly diverse range of problems and that the technique will be expanded to new pulse sequences, including multidimensional coherent vibrational spectroscopies such as the vibrational echo spectroscopy technique describe above. 

Owrutsky JC, Li M, Culver JP, Sarisky MJ, Yodh AG, Hochstrasser RM. Vibrational dynamics of condensed phase molecules studied by ultrafast infrared spectroscopy. In Lau A, Siebert F, Werncke W, eds. Time Resolved Vibrational Spectroscopy IV. Berlin Springer-Verlag, 1993 63-67. 

In recent years there has been significant interest in the extension of nonlinear optical spectroscopy to higher orders involving multiple time and/or frequency variables. The development of these multidimensional techniques is motivated by the desire to probe the microscopic details of a system that are obscured by the ensemble averaging inherent in linear spectroscopy. Much of the recent work to extend time domain vibrational spectroscopy to higher dimensionality has involved the use of nonresonant Raman-based techniques. The use of Raman techniques has followed directly from the rapid advancements in ultrafast laser technology for the visible and near-IR portions of the spectrum. Time domain nonresonant Raman spectroscopy provides access to an extremely... 

Despite the lower transport efficiency, the macropulse method is very effective at delivering large doses, which will be essential for the addition of vibrational spectroscopies to ultrafast pulse radiolysis. Vibrational spectroscopy is very useful for identifying transient species because of its sensitivity to molecular structure and the ability to... 

R. Lingle, Jr., X. Xu, S. Yu, H. Zhu, and J. B. Hopkins, J. Chem. Phys., 93, 5667 (1990). Ultrafast Investigation of Condensed Phase Chemical Reaction Dynamics Using Transient Vibrational Spectroscopy-Geminate Recombination, Vibrational Energy Relaxation, and Electronic Decay of the Iodine A Excited State. 

Scherzer T, Decker U. Real time FTIR-ATR spectroscopy to study the kinetics of ultrafast photopolymerization reactions induced by monochromatic UV light. Vibrational Spectroscopy. April 1999 Vol. 19(Issue 2) 385-398. 

L.W. Barbour, M. Hegadorn, and J.B. Asbury, Microscopic inhomogeneity and ultrafast orientational motion in an organic photovoltaic bulk heterojunction thin film studied with 2D IR vibrational spectroscopy, J. Phys. Chem. B, 110, 24281-24286 (2006). 

Grills, D. C. George, M. W. Fast and Ultrafast Time-resolved Mid-infrared Spectrometry using Lasers. In Handbook of Vibrational Spectroscopy, Chalmers, J. M., Griffiths, P. R., Eds. Wiley Chichester, UK, 2002 Vol. 1, pp... 

In summary, the ultrafast vibrational spectroscopy indicates that a molecule may within 50 fs make short angular and translational excursions which lead to rapid but only partial loss of frequency and angular correlation. On a slightly longer time scale undamped oscillations—librations and HB stretches— take place, and at still longer times the molecule rotates and breaks old and forms new HBs. The water molecule rotates in a concerted HB switching mode through a transition state with weak bifurcated HBs (Fig. 1.3). 

Schmidt JR, Roberts ST, Loparo JJ, Tokmtikoff A, Payer MD, Skinner JL (2007) Are water simulation models consistent with steady-state and ultrafast vibrational spectroscopy experiments Chem Phys 341 143-157... 

Recent developments in ultrafast laser technology have enabled the efficient generation of tunable femtosecond laser pulses from the UV to the far-infrared regions of the electromagnetic spectrum making femtosecond vibrational spectroscopy a versatile tool [8-10]. 

Among approaches in vibrational spectroscopy are differential and time-resolved IR and Raman spectroscopy, coherent anti-Stokes Raman scattering (CARS), Fourier transform infrared spectroscopy (FT-IR) multidimensional IR and RR spectroscopy, two-dimensional infrared echo and Raman echo [56], and ultrafast time-resolved spontaneous and coherent Raman spectroscopy the structure and dynamics of photogenerated transient spedes [50, 57]. 

All these recent developments demonstrate that the fast and ultrafast absorption, fluorescence, and vibrational spectroscopies continue to evolve synergetically and at a rather rapid pace. It is our hope that even more progress in the instrumentation and its application in stilbene photophysics and photochemistry would follow in the coming years. 

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