Observation of the screened potential and the Friedel oscillation by low-temperature scanning tunneling microscopy/spectroscopy

Using low-temperature scanning tunneling microscopy/spectroscopy we have developed a method for measuring electrostatic potential in high spatial and energy resolutions, and performed a real-space observation of the potential screened by two-dimensional surface electrons around step edges, where extra charges are localized, on the Si(1 1 1)√3 × √3-Ag surface. In the potential images, characteristic decay and the Friedel oscillation were clearly observed around the charges.     

Verwey transition in magnetite at high pressure: A new quantum critical point at the onset of metallization

We provide a detailed physical discussion of the existence of a quantum critical point (QCP) at the metallization threshold of an almost stoichiometric magnetite, with the critical pressure . A presence of an additional crossover or a critical line separating metallic and semiconducting states is proposed. A connection of the critical behavior to that of a spinless-fermion model with coupling of fermions to the lattice distortion is outlined.     

Photochemical reaction intermediates of benzyl chloride in condensed phase

Reaction intermediates produced upon the photolysis of benzyl chloride have been studied in glassy matrix and in solution. In the steady-state photolysis both benzyl radicals and structural isomers of benzyl chloride were formed in ethanol, while in 3-methylpentane the structural isomers were predominantly formed. The nanosecond laser photolyses of benzyl chloride in ethanol and in cyclohexane also generated benzyl radicals and structural isomers at room temperature. In acetonitrile, in addition to these species, benzyl cations were observed in the early stage after the photolysis.     

Allixin induction and accumulation by light irradiation.

Allixin, a phytoalexin isolated from garlic, was induced by irradiating fresh garlic cloves with sunlight or UV light. Induced allixin was analyzed by HPLC, and the accumulated amounts of allixin were 3.1-6.3 microg/g under experimental conditions.     

Optical Chirality Induced in Evaporated Poly(diacetylene) Film by Circularly Polarized Light

Summary: 10,12-tricosadiynoic acid films were deposited on glass substrate by vacuum evaporation proceess at substrate temperatures of 273 K and 313 K, and then photopolymerized using left- and right- circularly polarized light (CPL). The resulting prepared poly(diacetylene) films changed from blue phase to red phase successfully by sample annealing at 353 K for 10 min, and the absorption spectra well reflected the red phase. Surface morphology change was not observed by anneling at 353 K. Furthermore, the CD spectra revealed that the chirality induced by CPL at 313 K was stronger that at 273 K.     

Lithium potassium borate and lithium rubidium borate: new non‐linear optical crystals

The title compounds, LiKB₄O₇ and LiRbB₄O₇, are newly developed non‐linear optical crystals containing two kinds of anionic groups, namely (B₃O₈)^7? and (B₅O₁₀)^5?. The (B₃O₈)^7? groups form infinite spiral chains parallel to the [100] direction, which are interconnected by sharing O atoms with (B₅O₁₀)^5? groups.     

Intense THz-radiation from semiconductors under magnetic field irradiated with femtosecond laser pulses

The THz-radiation power from InAs reaches sub-mW level in a 1.7-T magnetic field irradiated with femtosecond laser pulses of 1.5-W average power. The THz-radiation power is related almost quadratically both to the magnetic field and to the excitation laser power. Furthermore, the THz-radiation spectrum is found to be controlled by the excitation pulsewidth, chirp direction of the excitation pulse, and the magnetic field.     

Orientation of a key glutamine residue in the BLUF domain from AppA revealed by mutagenesis, spectroscopy, and quantum chemical calculations

The flavin-adenine-dinucleotide-binding BLUF domain constitutes a new class of blue-light receptors, and the N-terminal domain of AppA is a representative of this family. A crystal structure of the BLUF domain from AppA suggested that a conserved Gln63 forms a hydrogen bond with the flavin N5 atom. Upon light excitation, this residue is proposed to undergo a approximately 180 degrees rotation that leads to a rearrangement of a hydrogen bonding network. However, crystallographic studies on the other BLUF proteins claimed an opposite orientation for the glutamine residue. In this communication, we have revealed the presence of a Gln63-to-N5 hydrogen bond in the dark state of AppA by a combined approach of mutagenesis, spectroscopy, and quantum chemical calculations. The present finding supports the view that the reorientation of the Gln63 side chain is a key event in the signaling state formation of BLUF proteins.     

Steroidal alkaloid glycosides, esculeosides C and D, from the ripe fruit of cherry tomato

Two new steroidal alkaloid glycosides, esculeosides C and D, have been isolated from the ripe fruit of Cherry tomato [Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF.], along with three known steroidal alkaloid glycosides, esculeoside A, esculeoiside B, and lycoperoside G. Their chemical structures were determined on the basis of spectroscopic data.