Near-Infrared Time-Resolved Optical Absorption Studies of the Reaction of Fully Reduced CytochromecOxidase with Dioxygen†

Biochemistry ◽  
2001 ◽  
Vol 40 (8) ◽  
pp. 2332-2339 ◽  
Author(s):  
Istvan Szundi ◽  
Guang-Ling Liao ◽  
Ólöf Einarsdóttir
Keyword(s):  
Optical Absorption ◽  
Near Infrared ◽  
Time Resolved ◽  
Absorption Studies

Infrared Studies of the Double Acceptor Zinc in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
A. Dörnen ◽  
R. Kienle ◽  
K. Thonke ◽  
P. Stolz ◽  
G. Pensl ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Charge State ◽  
Crystal Field ◽  
Absorption Spectra ◽  
Ground State ◽  
Near Infrared ◽  
Mid Infrared ◽  
Absorption Studies ◽  
Infrared Studies ◽  
Neutral Charge State

AbstractIn the present paper, optical absorption studies on the neutral charge state of the double acceptor zinc in silicon are presented. Measurements were carried out in the mid infrared (MIR) and in the near infrared (NIR) region. The MIR absorption spectra show the excitation series of an effective-masslike hole, from which the Zn° level position is calculated to be at Ev + 319. 1 meV. A splitting of the ground state into 3 sublevels is assigned to hole-hole coupling and crystal-field splitting. Absorption spectra obtained in the NIR are interpreted in terms of an A° X-type bound exciton.

scholarly journals EPR, UV-Visible, and Near-Infrared Spectroscopic Characterization of Dolomite

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
S. Lakshmi Reddy ◽  
R. L. Frost ◽  
G. Sowjanya ◽  
N. C. G. Reddy ◽  
G. Siva Reddy ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Spectroscopic Characterization ◽  
Distorted Octahedron ◽  
Spectral Studies ◽  
Indian Origin ◽  
Absorption Studies ◽  
Light Green

Dolomite mineral samples having white and light green colors of Indian origin have been characterized by EPR, optical, and NIR spectroscopy. The optical spectrum exhibits a number of electronic bands due to presence of Fe(III) ions in the mineral. From EPR studies, the parameters ofgfor Fe(III) andg,A, andDfor Mn(II) are evaluated and the data confirm that the ions are in distorted octahedron. Optical absorption studies reveal that Fe(III) is in distorted octahedron. The bands in NIR spectra are due to the overtones and combinations of water molecules. Thus EPR and optical absorption spectral studies have proven useful for the study of the solid state chemistry of dolomite.

Subnanosecond time-resolved optical absorption studies of electron solvation in ice

1983 ◽  
Vol 87 (21) ◽  
pp. 4292-4294 ◽  
Author(s):  
John M. Warman ◽  
Marinus Kunst ◽  
Charles D. Jonah
Keyword(s):  
Optical Absorption ◽  
Time Resolved ◽  
Electron Solvation ◽  
Absorption Studies ◽  
Subnanosecond Time

scholarly journals Real-time observation of tetrapyrrole binding to an engineered bacterial phytochrome

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yusaku Hontani ◽  
Mikhail Baloban ◽  
Francisco Velazquez Escobar ◽  
Swetta A. Jansen ◽  
Daria M. Shcherbakova ◽  
...  
Keyword(s):  
Real Time ◽  
Rational Design ◽  
Near Infrared ◽  
Fluorescent Proteins ◽  
Covalent Bond ◽  
Binding Pocket ◽  
Tissue Imaging ◽  
Covalent Attachment ◽  
Time Resolved

AbstractNear-infrared fluorescent proteins (NIR FPs) engineered from bacterial phytochromes are widely used for structural and functional deep-tissue imaging in vivo. To fluoresce, NIR FPs covalently bind a chromophore, such as biliverdin IXa tetrapyrrole. The efficiency of biliverdin binding directly affects the fluorescence properties, rendering understanding of its molecular mechanism of major importance. miRFP proteins constitute a family of bright monomeric NIR FPs that comprise a Per-ARNT-Sim (PAS) and cGMP-specific phosphodiesterases - Adenylyl cyclases - FhlA (GAF) domain. Here, we structurally analyze biliverdin binding to miRFPs in real time using time-resolved stimulated Raman spectroscopy and quantum mechanics/molecular mechanics (QM/MM) calculations. Biliverdin undergoes isomerization, localization to its binding pocket, and pyrrolenine nitrogen protonation in <1 min, followed by hydrogen bond rearrangement in ~2 min. The covalent attachment to a cysteine in the GAF domain was detected in 4.3 min and 19 min in miRFP670 and its C20A mutant, respectively. In miRFP670, a second C–S covalent bond formation to a cysteine in the PAS domain occurred in 14 min, providing a rigid tetrapyrrole structure with high brightness. Our findings provide insights for the rational design of NIR FPs and a novel method to assess cofactor binding to light-sensitive proteins.

scholarly journals Giant enhancement of THz-frequency optical nonlinearity by phonon polariton in ionic crystals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yao Lu ◽  
Qi Zhang ◽  
Qiang Wu ◽  
Zhigang Chen ◽  
Xueming Liu ◽  
...  
Keyword(s):  
Near Infrared ◽  
Optical Nonlinearity ◽  
Ionic Crystals ◽  
Nonlinear Optical Susceptibility ◽  
Time Resolved ◽  
Light Coupling ◽  
Tremendous Progress ◽  
Fundamental Research ◽  
Ionic Contribution ◽  
Time Resolved Imaging

AbstractThe field of nonlinear optics has grown substantially in past decades, leading to tremendous progress in fundamental research and revolutionized applications. Traditionally, the optical nonlinearity for a light wave at frequencies beyond near-infrared is observed with very high peak intensity, as in most materials only the electronic nonlinearity dominates while ionic contribution is negligible. However, it was shown that the ionic contribution to nonlinearity can be much larger than the electronic one in microwave experiments. In the terahertz (THz) regime, phonon polariton may assist to substantially trigger the ionic nonlinearity of the crystals, so as to enhance even more the nonlinear optical susceptibility. Here, we experimentally demonstrate a giant second-order optical nonlinearity at THz frequency, orders of magnitude higher than that in the visible and microwave regimes. Different from previous work, the phonon-light coupling is achieved under a phase-matching setting, and the dynamic process of nonlinear THz generation is directly observed in a thin-film waveguide using a time-resolved imaging technique. Furthermore, a nonlinear modification to the Huang equations is proposed to explain the observed nonlinearity enhancement. This work brings about an effective approach to achieve high nonlinearity in ionic crystals, promising for applications in THz nonlinear technologies.

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