Search

The authors make the following additions and corrections to the paper, C. Baiz et al., Vibrational Spectroscopic Map, Vibrational Spectroscopy, and Intermolecular Interaction. Chem. Rev. 2020, 120, 7152?7218. 1. The below funding sources should be added to the Acknowledgments section on pages 7204 and 7205: NHG acknowledges support from the National Science Foundation (CHE-1905395). AT thanks the Advanced Materials for Energy-Water Systems (AMEWS) Center (DE-AC02-06CH11357) for support. Thus, the Acknowledgments should be as follows: This work was supported by IBS-R023-D1 (MC). BB wishes to thank the European Union’s Horizon 2020 under the Marie Sk?odowska-Curie Grant Agreement No. 665778, as well as the National Science Centre, Poland (grant no. 2016/23/P/ST4/01720). CRB acknowledges generous support from the National Science Foundation (CHE-847199, BIO-1815354 ) , the National Ins t i t u tes o f Hea l t h (R35GM133359), and the Welch Foundation (F-1891). NHG acknowledges support from the National Science Foundation (CHE-1905395). MWDH-H and JDH thank the University of Nottingham, Green Chemicals Beacon for funding toward this research. AT thanks the Advanced Materials for Energy-Water Systems (AMEWS) Center (DEAC02-06CH11357) for support. MCT acknowledges support from Department of Energy (DE-SC0018983), National Science Foundation (1552996), and National Institutes of Health (GM114500). AGD would like to thank Prof. Andrei Tokmakoff for discussing amide modes when he was a Ph.D. student. LW acknowledges the support from the National Institutes of Health through Award R01GM130697. SAC acknowledges support from National Science Foundation (CHE-1565471). 2. The affiliations of Minhaeng Cho and Kijeong Kwak on page 7201 should be corrected as follows: Minhaeng Cho ? Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea; Department of Chemistry, Korea University, Seoul 02841, Republic of Korea Kijeong Kwac ? Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea 3. Reference 329 on page 7214 should be replaced with the following paper: (329) Sul, S; Karaiskaj, D.; Jiang Y.; Ge, N.-H. Conformations of N-Acetyl-L-Prolinamide by Two-Dimensional Infrared Spectroscopy. J. Phys. Chem. B 2006, 110, 19891?19905. 4. A correction in the biography of Magnus Hanson-Heine on page 7203 should be made. MH-H received his Ph.D. in 2014, not 2010.

Vibrational spectroscopy is an essential tool in chemical analyses, biological assays, and studies of functional materials. Over the past decade, various coherent nonlinear vibrational spectroscopic techniques have been developed and enabled researchers to study time-correlations of the fluctuating frequencies that are directly related to solute-solvent dynamics, dynamical changes in molecular conformations and local electrostatic environments, chemical and biochemical reactions, protein structural dynamics and functions, characteristic processes of functional materials, and so on. In order to gain incisive and quantitative information on the local electrostatic environment, molecular conformation, protein structure and interprotein contacts, ligand binding kinetics, and electric and optical properties of functional materials, a variety of vibrational probes have been developed and site-specifically incorporated into molecular, biological, and material systems for time-resolved vibrational spectroscopic investigation. However, still, an all-encompassing theory that describes the vibrational solvatochromism, electrochromism, and dynamic fluctuation of vibrational frequencies has not been completely established mainly due to the intrinsic complexity of intermolecular interactions in condensed phases. In particular, the amount of data obtained from the linear and nonlinear vibrational spectroscopic experiments has been rapidly increasing, but the lack of a quantitative method to interpret these measurements has been one major obstacle in broadening the applications of these methods. Among various theoretical models, one of the most successful approaches is a semiempirical model generally referred to as the vibrational spectroscopic map that is based on a rigorous theory of intermolecular interactions. Recently, genetic algorithm, neural network, and machine learning approaches have been applied to the development of vibrational solvatochromism theory. In this review, we provide comprehensive descriptions of the theoretical foundation and various examples showing its extraordinary successes in the interpretations of experimental observations. In addition, a brief introduction to a newly created repository Web site (http://frequencymap.org) for vibrational spectroscopic maps is presented. We anticipate that a combination of the vibrational frequency map approach and state-of-the-art multidimensional vibrational spectroscopy will be one of the most fruitful ways to study the structure and dynamics of chemical, biological, and functional molecular systems in the future.

The thickness-dependent interfacial band structure was determined for thin films of Co(6) on Ag(111) by angle-resolved two-photon photoemission spectroscopy.

Using ultrafast two-dimensional infrared spectroscopy (2D-IR), a vibrational probe (thiocyanate, SCN−) was used to investigate the hydrogen bonding network of the protic ionic liquid ethyl-ammonium nitrate (EAN) in comparison to H2O. The 2D-IR experiments were performed in both parallel (⟨ZZZZ⟩) and perpendicular (⟨ZZXX⟩) polarizations at room temperature. In EAN, the non-Gaussian lineshape in the FTIR spectrum of SCN− suggests two sub-ensembles. Vibrational relaxation rates extracted from the 2D-IR spectra provide evidence of the dynamical differences between the two sub-ensembles. We support the interpretation of two sub-ensembles with response function simulations of two overlapping bands with different vibrational relaxation rates and, otherwise, similar dynamics. The measured rates for spectral diffusion depend on polarization, indicating reorientation-induced spectral diffusion (RISD). A model of restricted molecular rotation (wobbling in a cone) fully describes the observed spectral diffusion in EAN. In H2O, both RISD and structural spectral diffusion contribute with similar timescales. This complete characterization of the dynamics at room temperature provides the basis for the temperature-dependent measurements in Paper II of this series. [ABSTRACT FROM AUTHOR]

Ultrafast two-dimensional infrared spectroscopy of a thiocyanate vibrational probe (SCN-) was used to investigate local dynamics in alkylimidazolium bis-[trifluoromethylsulfonyl]imide ionic liquids ([Imn,1][Tf2N], n = 2, 4, 6) at temperatures from 5 to 80 °C. The rate of frequency fluctuations reported by SCN- increases with increasing temperature and decreasing alkyl chain length. Temperature-dependent correlation times scale proportionally to temperature-dependent bulk viscosities of each ionic liquid studied. A multimode Brownian oscillator model demonstrates that very low frequency (<10 cm-1) modes primarily drive the observed spectral diffusion and that these modes broaden and blue shift on average with increasing temperature. An Arrhenius analysis shows activation barriers for local motions around the probe between 5.5 and 6.5 kcal/mol that are very similar to those for translational diffusion of ions. [Im6,1][Tf2N] shows an unexpected decrease in activation energy compared to [Im4,1][Tf2N] that may be related to mesoscopically ordered polar and nonpolar domains. A model of dynamics on a rugged potential energy landscape provides a unifying description of the observed Arrhenius behavior and the Brownian oscillator model of the low frequency modes. [ABSTRACT FROM AUTHOR]

Two-photon photoemission of image potential states above monolayers of p-xylene/Ag(111) shows that electrons with different momenta have very different rise and decay rates as a function of parallel momentum. The dynamics are due to energy and momentum loss (intraband relaxation), which is modeled as a stochastic process isomorphic to the overdamped motion of harmonic oscillator.

The low-temperature equilibrium and nonequilibrium solvation dynamics of an excess electron in bulk and at a surface interface are characterized using mixed quantum/classical simulation methods. The temperature dependence of the bulk response is shown to minimal, indicating that the large-scale hydrogen bond breaking and diffusive motion may not be playing roles in the solvation dynamics.

The CO2 ν3 asymmetric stretching mode is established as a vibrational chromophore for ultrafast two-dimensional infrared (2D-IR) spectroscopic studies of local structure and dynamics in ionic liquids, which are of interest for carbon capture applications. CO2 is dissolved in a series of 1-butyl-3-methylimidazolium-based ionic liquids ([C4C1im][X], where [X]- is the anion from the series hexafluorophosphate (PF6-), tetrafluoroborate (BF4-), bis-(trifluoromethyl)sulfonylimide (Tf2N-), triflate (TfO-), trifluoroacetate (TFA-), dicyanamide (DCA-), and thiocyanate (SCN-)). In the ionic liquids studied, the ν3 center frequency is sensitive to the local solvation environment and reports on the timescales for local structural relaxation. Density functional theory calculations predict charge transfer from the anion to the CO2 and from CO2 to the cation. The charge transfer drives geometrical distortion of CO2, which in turn changes the ν3 frequency. The observed structural relaxation timescales vary by up to an order of magnitude between ionic liquids. Shoulders in the 2D-IR spectra arise from anharmonic coupling of the ν2 and ν3 normal modes of CO2. Thermal fluctuations in the ν2 population stochastically modulate the ν3 frequency and generate dynamic cross-peaks. These timescales are attributed to the breakup of ion cages that create a well-defined local environment for CO2. The results suggest that the picosecond dynamics of CO2 are gated by local diffusion of anions and cations. [ABSTRACT FROM AUTHOR]

We utilize two-color two-dimensional infrared spectroscopy to measure the intermolecular coupling between azide ions and their surrounding water molecules in order to gain information about the nature of hydrogen bonding of water to ions. Our findings indicate that the main spectral contribution to the intermolecular cross-peak comes from population transfer between the asymmetric stretch vibration of azide and the OD-stretch vibration of D2O. The azide-bound D2O bleach/stimulated emission signal, which is spectrally much narrower than its linear absorption spectrum, shows that the experiment is selective to solvation shell water molecules for population times up to ∼500 fs. The waters around the ion are present in an electrostatically better defined environment. Afterwards, ∼1 ps, the sample thermalizes and selectivity is lost. On the other hand, the excited state absorption signal of the azide-bound D2O is much broader. The asymmetry in spectral width between bleach/stimulated emission versus excited absorption has been observed in very much the same way for isotope-diluted ice Ih, where it has been attributed to the anharmonicity of the OD potential. [ABSTRACT FROM AUTHOR]

We demonstrate a method to collect purely absorptive three-dimensional (3D) fifth-order vibrational spectra on the model system CO2 in H2O. The six beam interferometer is described, as well as a method to experimentally determine the phase of the 3D spectrum. The measured spectra agree very well with simulations of the data based on the cumulant expansion. There are five peaks corresponding to different paths up and down the vibrational ladder. The positions, signs, and amplitudes of the peaks agree with theoretical predictions, and the intensities of the peaks scale linearly with concentration. Based on the concentration dependence and agreement between the simulations and measurements, we conclude that cascaded lower order signals contribute negligibly to the observed signal. [ABSTRACT FROM AUTHOR]

Characterizing the dynamics of the OH stretch in isotopically substituted liquid water (HOD in D2O) in terms of three-point frequency fluctuation correlation functions and joint probability densities shows that dynamics during hydrogen bond rearrangements occur primarily along a coordinate which is perpendicular to the spectroscopic coordinate. Molecular dynamics simulations show that three-point correlation functions are sensitive to this motion, unlike two-point correlation functions, and can select sets of trajectories which linger in the area of the transition state. Three-dimensional-infrared correlation spectroscopy could potentially measure these dynamics, though motional narrowing significantly changes the shape of the resulting spectra. [ABSTRACT FROM AUTHOR]

The ability of time- and angle-resolved two-photon photoemission to estimate the size distribution of electron localization in the plane of a metal–adsorbate interface is discussed. It is shown that the width of angular distribution of the photoelectric current is inversely proportional to the electron localization size within the most common approximations in the description of image potential states. The localization of the n=1 image potential state for two monolayers of butyronitrile on Ag(111) is used as an example. For the delocalized n=1 state, the shape of the signal amplitude as a function of momentum parallel to the surface changes rapidly with time, indicating efficient intraband relaxation on a 100 fs time scale. For the localized state, little change was observed. The latter is related to the constant size distribution of electron localization, which is estimated to be a Gaussian with a 15±4 Å full width at half maximum in the plane of the interface. A simple model was used to study the effect of a weak localization potential on the overall width of the angular distribution of the photoemitted electrons, which exhibited little sensitivity to the details of the potential. This substantiates the validity of the localization size estimate. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Angle-resolved two-photon photoemission (2PPE) spectroscopy is used to determine the thickness-dependent interfacial band structure for thin films of [C.sub.60] on Ag(111). The results have shown that angle-resolved 2PPE can be used as a direct experimental probe of band structure in systems with quite complicated electronic energy levels.