Topics in Current Chemistry (2018) 376:28
1 3
has recently been undertaken in order to dissect these contributions and an accurate interpretation is often not trivial [100, 108–111]. The role and interpretation of
vibronic coupling is a major topic in the 2D electronic spectroscopy contribution.
6 How is this Collection Organized
There are several ways to classify the different kinds of spectroscopies. As discussed
previously, the spectral range is a useful way of doing this because it leads to a separation of the most important physicochemical processes involved. In this regard,
four contributions of this volume focus mainly on different aspects of vibrational
dynamics and interactions, while two contributions deal with predominately with
electronic interactions. The reader will notice that though, some physicochemical
processes like, e.g., the role of vibrational coupling will eventually appear in more
than one contribution, but in different contexts or in different electronic states.
The interaction of very low photon energies (see Fig. 2) with small molecules and
other simple physical systems is addressed in the contribution titled “Two-dimensional spectroscopy at terahertz frequencies” by Lu et al. Multidimensional terahertz
spectroscopy is used to understand examples like gas-phase molecular rotations,
spin precessions in magnetic systems, as well as liquid molecular dynamics and
interactions. The contribution also features how terahertz methods can be combined
with optical excitation and detection through non-resonant Raman scattering, leading to hybrid methods like 2D THz-Raman techniques.
The next photon energy range is covered by the contribution “Ultrafast Structural Molecular Dynamics Investigated with 2D Infrared Spectroscopies” by Kraack.
Several examples of physicochemical processes like vibrational coupling in molecules, spectral diffusion dynamics, chemical exchange of chemical bond formation and breaking, intra- and intermolecular energy transfer are discussed in the
light of various kinds of 2D infrared spectroscopy methods. The contribution also
covers in detail several state-of-the-art variants of 2D infrared spectroscopy involving, e.g., electrochemistry, diffraction-limited microscopy, transient applications of
2D IR methods, as well as hybrid methods like vibrational-electronic methods are
presented.
The role of Raman vibrations in the electronically excited state dynamics is the
focus of the contribution “Multidimensional Vibrational Coherence Spectroscopy”
by Buckup and Leonard. In particular, the examples portray mapping of structural
dynamics along a photoreaction, identification of transient molecular species, and
chemical/structural heterogeneity of complex molecular systems in condensed
phase.
Another example of how structural dynamics along a photoreaction can be monitored by multidimensional spectroscopies is discussed in the contribution “TwoDimensional Resonance Raman Signatures of Vibronic Coherence Transfer in
Chemical Reactions” by Guo et al. In particular, a variation of a 2D Raman spectroscopy technique, labeled 2D resonance Raman, is used to highlight correlated
distributions of reactant and product geometries and structural heterogeneity in an
ensemble for a prototype photodissociation reaction of triiodide.
14
Reprinted from the journal
1 3
has recently been undertaken in order to dissect these contributions and an accurate interpretation is often not trivial [100, 108–111]. The role and interpretation of
vibronic coupling is a major topic in the 2D electronic spectroscopy contribution.
6 How is this Collection Organized
There are several ways to classify the different kinds of spectroscopies. As discussed
previously, the spectral range is a useful way of doing this because it leads to a separation of the most important physicochemical processes involved. In this regard,
four contributions of this volume focus mainly on different aspects of vibrational
dynamics and interactions, while two contributions deal with predominately with
electronic interactions. The reader will notice that though, some physicochemical
processes like, e.g., the role of vibrational coupling will eventually appear in more
than one contribution, but in different contexts or in different electronic states.
The interaction of very low photon energies (see Fig. 2) with small molecules and
other simple physical systems is addressed in the contribution titled “Two-dimensional spectroscopy at terahertz frequencies” by Lu et al. Multidimensional terahertz
spectroscopy is used to understand examples like gas-phase molecular rotations,
spin precessions in magnetic systems, as well as liquid molecular dynamics and
interactions. The contribution also features how terahertz methods can be combined
with optical excitation and detection through non-resonant Raman scattering, leading to hybrid methods like 2D THz-Raman techniques.
The next photon energy range is covered by the contribution “Ultrafast Structural Molecular Dynamics Investigated with 2D Infrared Spectroscopies” by Kraack.
Several examples of physicochemical processes like vibrational coupling in molecules, spectral diffusion dynamics, chemical exchange of chemical bond formation and breaking, intra- and intermolecular energy transfer are discussed in the
light of various kinds of 2D infrared spectroscopy methods. The contribution also
covers in detail several state-of-the-art variants of 2D infrared spectroscopy involving, e.g., electrochemistry, diffraction-limited microscopy, transient applications of
2D IR methods, as well as hybrid methods like vibrational-electronic methods are
presented.
The role of Raman vibrations in the electronically excited state dynamics is the
focus of the contribution “Multidimensional Vibrational Coherence Spectroscopy”
by Buckup and Leonard. In particular, the examples portray mapping of structural
dynamics along a photoreaction, identification of transient molecular species, and
chemical/structural heterogeneity of complex molecular systems in condensed
phase.
Another example of how structural dynamics along a photoreaction can be monitored by multidimensional spectroscopies is discussed in the contribution “TwoDimensional Resonance Raman Signatures of Vibronic Coherence Transfer in
Chemical Reactions” by Guo et al. In particular, a variation of a 2D Raman spectroscopy technique, labeled 2D resonance Raman, is used to highlight correlated
distributions of reactant and product geometries and structural heterogeneity in an
ensemble for a prototype photodissociation reaction of triiodide.
14
Reprinted from the journal