Proceedings of the 14th International Conference, Niigata, Japan, July 25–30, 2004
We have developed the method of picosecond time-resolved crystallography and used this technique to investigate structural dynamics in biological macromolecules at ambient temperature. Time-resolved snapshots of myoglobin following flash photolysis of the CO adduct were determined with 150 ps time resolution and < 2 Å spatial resolution. The structures reveal numerous sites in which CO becomes...
One and two color three pulse photon echo spectroscopy is used to probe ultrafast energy transfer, energetic disorder and correlation between the 96 non-equivalent Chlorophylls in the photosynthetic light-harvesting complex Photosystem I.
Ultrafast optical responses in β-carotene and lycopene depend on the pump wavelength. Excess vibrational energy induced by the photoexcitation remains longer than several picoseconds in the excited states and slows down the relaxation kinetics.
Pump-dump-probe and pump-repump-probe transient absorption experiments with broad-band detection have allowed the identification of a hitherto unknown relaxation pathway in β-carotene which opens after excitation to the S2 state with high-energy photons.
Wavepacket dynamics on the ground and optically dark, first electronic State of all-trans-β-carotene are studied with 16 fs time resolution using pump-degenerate four-wave mixing spectroscopy. Moreover control over the vibrational ground state modes is shown.
Two-dimensional integrated three-pulse photon echo measurement was carried out on saccharide glasses and in poly vinylalcohol (PVA). The echo signals were modulated by coherent molecular vibrations which depended on the delay between the first and the second pulse. For saccharide glasses, a low-frequency critically damped oscillation at ∼40cm−1, which was assigned to the glass phonon mode, was also...
A method for direct measurement of the system-bath coupling strength in molecules and molecular aggregates, based on the three pulse photon echo technique with non-trivial time ordering of interacting laser pulses, is proposed and realized. A surprisingly low magnitude of the Huang-Rhys factor (∼ 1) was measured for the natural molecular aggregates (chlorosomes from the Cf. aurantiacus bacteria) at...
Low frequency modes of PYP (photoactive yellow protein), its several mutant and analogue systems have been investigated by fluorescence up-conversion and resonance Raman scattering techniques, complemented by DFT and ab initio MO calculations. Assignments of the oscillatory components to particular vibrations are proposed. Their role in photoisomerization reaction is discussed.
Remarkable oscillatory components are observed in the 2-dimentional time-wavelength map of ultrafast fluorescence for photoactive yellow protein, by using the optical Kerr gating system with 180-fs time resolution and 5-nm spectral resolution.
Ultrafast dispersed pump-dump-probe spectroscopy was applied to a model Green Fluorescent Protein chromophore in solution. Sub-ps photodynamics in the excited and ground State has been observed that is ascribed to a hula-twist isomerization mechanism.
Femtosecond laser pulses that control the photoisomerization of retinal in rhodopsin are numerically designed using quantum optimal control theory. Preparation of squeezed reactant wave packets through multiple electronic transitions is essential for creating localized product wave packets.
The primary events in bacteriorhodopsin are investigated by coherent infrared emission spectroscopy of oriented purple membranes. Long-lived vibrational motions involving charge displacements are observed following sudden (<11 fs) macroscopic membrane polarization appearing upon visible excitation.
The difference absorption spectra and the lifetimes of the four singlet states in all-trans-spirilloxanthin (number of double bonds, n=13) involved were separately determined by the singular-value decomposition and global fitting, using the title sequential model. The lifetimes of the 1Bu +, 3Ag −, and 1Bu − states identified together for the first time were determined to...
Electron-vibration coupling in alcohol dehydrogenase and zinc substituted myoglobin was calculated using a quantum mechanics/molecular mechanics method. Good agreement with experimental measurements demonstrates the viability of the method.
The rebinding dynamics of NO in photolyzed MbNO are investigated by femtosecond mid-IR spectroscopy. The spectra with conformer-specific kinetics reveal the details of ligand binding trajectories and suggest that the conformational relaxation controls ligand binding.
We demonstrate vibrational climbing up to level v=6 in carboxyhemoglobin by use of intense negatively-chirped infrared pulses. This technique gave new spectroscopic insight into carboxy-hemoglobin, such as transition frequencies and dephasing times up to the v=6 to v=7 vibrational transition.
Polarization-dependent transient infrared spectroscopy probes the restricted ultrafast orientational motion of CO inside the Xe4 cavity of myoglobin. The four-point correlation function < μ(0)μ(0)μ(T)μ(T+t)> does not factorize, only its full evaluation reproduces the observed anisotropies.
We report spectrally-integrated, visible-pump, mid-infrared probe studies of the CO ligand in myoglobin. Supported by density functional calculations, we find that the CO oscillator strength and frequency changes occur on disparate timescales following dissociation.
Spectral and temporal analysis of diagonal and cross peaks in two-dimensional infrared response from Trp-Ala-Alkyl didpeptide indicates a change in structure and in ultra-fast backbone dynamics when the molecule inserts into a membrane.
It has been known that three-photon absorption of DNA or protein is one of the causes of phototoxicity. Here, we apply coherent control to enhance the contrast between the two-photon absorption of fluorescent label and the three-photon absorption of biomaterial with engineered cost function, leading to effectively reduced three-photon absorption with few loss of valuable two-photon fluorescence.