Ultrafast chemical dynamics
Introduction to the themed issue of PCCP on ultrafast chemical dynamics.
Ultrafast soft-mode driven charge relocation in an ionic crystal
Transient electron density maps are directly measured by femtosecond X-ray powder diffraction in potassium dihydrogen phosphate (KDP).
Excited-state dynamics and efficient triplet formation in phenylthiophene compounds
Transient absorption spectroscopy reveals the ultrafast excited-state relaxation dynamics and efficient, picosecond-scale intersystem crossing kinetics of three closely-related phenylthiophene compounds.
Simulations of X-ray
absorption spectra: the effect of the solvent
We perform QM/MM molecular dynamics simulations on [Pt2(P2O5H2)4]4−. This is used to calculate the ground state X-ray absorption spectrum of the complex, showing a significant solvent effect, which has possible important implications for the structural analysis of molecules in solution.
Dynamics of fluorescence depolarisation in star-shaped
Fluorescence anisotropy dynamics are measured in star-shaped fluorene molecules. Two processes are observed: a fast 500 fs depolarisation assigned to exciton localisation, and a slower 3–8 ps process associated with energy transfer between arms.
The Paternò–Büchi reaction: importance of triplet states in the excited-state reaction pathway
The Paternò–Büchi reaction is studied in an isolated molecule with femtosecond time-resolution, using the [2.2]paracyclophane molecular scaffold.
Ultrafast exciton dynamics after Soret- or Q-band excitation of a directly β,β′-linked bisporphyrin
A comparative transient absorption study of a Zn-porphyrin monomer and its corresponding dimer shows the influence of excitonic coupling on temporal relaxation.
Band-edge ultrafast pump–probe
spectroscopy of core/shell CdSe/CdS rods: assessing electron delocalization by effective mass calculations
Differential transmission of CdSe/CdS nanorod samples with different core sizes was measured, excitation resonant to the core transition. The bleaching ratio between dot and rod transitions increases with dot size.
The effect of point mutation on the equilibrium structural fluctuations of ferric Myoglobin
Distinct ultrafast equilibrium fluctuations of different ferric haem protein conformational substates are revealed using 2D-IR spectroscopy.
electron transfer and solvation dynamics in aqueous clusters: comparison of the photoexcited iodide- water pentamer and the water pentamer anion
I−(H2O)5 photoinduced electron transfer: the excited electron detaches rapidly from the iodine atom and is subsequently stabilized by the gradual iodine-driven reorganization of the water cluster moiety.
Hydration and temperature interdependence of
protein picosecond dynamics
Protein dynamics dominate the THz permittivity for T < 265 K showing that motions most dependent on the dynamical transition are on the >1 ps time scale.
The molecular underpinnings of a solute-pump/
solvent-probe spectroscopy: the theory of polarizability response spectra and an application to preferential solvation
The molecular motions singled out by a novel kind of spectroscopy are simulated and identified for the first time.
Rotational dynamics of
thiocyanate ions in highly concentrated aqueous solutions
Rotational dynamics of chaotropic thiocyanate ions in highly concentrated aqueous solutions studied by IR pump–probe spectroscopy.
IR spectroscopy of polymeric cytosine nucleic acids reveal the long-lived species is due to a localised state
A dark 1nπ* state is observed in UV-excited cytosine polymers and its lifetime is lengthened relative to the monomer.
Aqueous solvation of amphiphilic solutes: concentration and temperature dependent study of the ultrafast polarisability relaxation dynamics
We report an investigation of aqueous solutions of TMAO and TBA as a function of concentration and temperature using the ultrafast optically heterodyne detected optical Kerr effect.
Tracking energy transfer from excited to accepting modes: application to
water bend vibrational relaxation
The energy flow from a bend-vibrationally excited water molecule in aqueous solution can be followed in molecular detail via a Poisson bracket work and power formulation. The bend energy decay, in red, is associated with a dominant energy transfer to water rotation, rather than to translation.
The combined effect of
cations and anions on the dynamics of water
The reorientation dynamics of water hydrating cations and anions are studied with femtosecond mid-infrared spectroscopy. It is found that ions influence the dynamics of the hydration shells of their counter-ions.
Investigation of multiple electronic excited state relaxation pathways following 200 nm photolysis of gas-phase
Ultrafast deactivation of imidazole following UV excitation is investigated experimentally by probing multiple photoproducts.
Ultrafast internal conversion in a low band gap
polymer for photovoltaics: experimental and theoretical study
Exploiting the combination of ultrafast transient absorption measurements (sub-10 fs time resolution) and quantum chemical DFT//TDDFT calculations we investigate the ultrafast dynamics in a low band gap polymer (PCPDTBT) of great interest for organic photovoltaics, rationalizing the internal conversion photophysical processes occurring after photoexcitation.
spectroscopy with sub-10 fs deep-ultraviolet pulses
Sub-10 fs deep-ultraviolet pulses are utilized in the ultrafast spectroscopy for the first time.
Photoexcited structural dynamics of an
azobenzene analog 4-nitro-4′-dimethylamino-azobenzene from femtosecond stimulated Raman
Schematic potential energy surface for the photoinitiated trans → cis isomerization of 4-nitro-4′-dimethylamino-azobenzene showing the initial dilation of the CNN bend followed by quick torsional motions.
Vibrational dynamics of acetate in D2O studied by infrared pump–probe
The infrared pump–probe signal of the asymmetric stretching mode in D2O shows an oscillatory component with a wavenumber of 80 cm−1, which is assigned as an intermolecular mode.
Solvent-dependent activation of intermediate excited states in the energy relaxation pathways of spheroidene
Environment dependence of ultrafast excited state dynamics in spheroidene and appearance of an intermediate state in the case of a low polarizability solvent.
Femtosecond fluorescence study of the reaction pathways and nature of the reactive S1 state of
Femtosecond fluorescence of cis-stilbene showed two components from different potential regions and indicated isomerization/cyclization branching occurring before the CC twisting.
LIAD-fs scheme for studies of ultrafast laser interactions with gas phase biomolecules
A new technique for ultrashort laser studies of biomolecules, liberated into the gas phase via laser induced acoustic desorption (LIAD).
Ultrafast primary processes of an iron-(III)
azido complex in solution induced with 266 nm light
The photodissociation dynamics of azide radicals from an iron complex are studied with femtosecond UV-pump–mid-IR probe spectroscopy.
Dynamic structures of aqueous oxalate and the effects of counterions seen by 2D IR
Two dimensional vibrational echo and FTIR spectroscopy supported by DFT calculations reveal contact ion pairs in caesium oxalate solutions.
Photophysics of the galvinoxyl free radical revisited
The galvinoxyl free radical converts 3 eV (70 kcal mol−1) of electronic energy within less than 200 femtoseconds into vibrational energy.
Ultrafast spin-state photoswitching in a crystal and slower consecutive processes investigated by femtosecond optical
spectroscopy and picosecond X-ray diffraction
Ultrafast probes are combined to study spin state photo- switching dynamics in two spin-crossover molecular polymorphs.
Two-dimensional infrared spectroscopy of neat ice Ih
Isotropic and anisotropic 2D-IR spectra of neat ice Ih, reporting on the couplings that give rise to its peculiar lineshape.
Femtosecond dynamics of
The B 1B1 state of c-C3H2 has been investigated by femtosecond time-resolved photoelectron spectroscopy.
Discrimination between coupling networks of glucopyranosides varying at a single stereocenter using two-dimensional vibrational correlation spectroscopy
Two-dimensional infrared correlation spectra show significant differences in the coupling networks of anomers that vary at a single stereochemical center.
Time-dependent quantum dynamical simulations of C2 condensation under extreme conditions
Quantum dynamical simulations of carbon vapor show that nonadiabatic electronic stopping leads to fast aggregation of C2 molecules into carbon nanostructures.
H-abstraction is more efficient than cis–trans isomerization in (4-methylcyclohexylidene)
fluoromethane. An ab initio molecular dynamics study
Ab initio molecular dynamics is used to unravel the different pathways that (4-methylcyclohexylidene) fluoromethane undergoes after light irradiation.
Ultrafast vibrational energy relaxation of the water bridge
Femtosecond mid-infrared spectroscopy is used to study the vibrational relaxation of water molecules constituting a so-called water bridge.
About this collection
PCCP is delighted to present a collection of articles on the theme of ultrafast chemical dynamics, Guest Edited by Klaas Wynne (University of Glasgow, UK) and Neil T. Hunt (University of Strathclyde, UK).