Optically Unraveling the Edge Chirality‐Dependent Band Structure and Plasmon Damping in Graphene Edges

The nontrivial topological origin and pseudospinorial character of electron wavefunctions make edge states possess unusual electronic properties. Twenty years ago, the tight‐binding model calculation predicted that zigzag termination of 2D sheets of carbon atoms have peculiar edge states, which show potential application in spintronics and modern information technologies. Although scanning probe microscopy is employed to capture this phenomenon, the experimental demonstration of its optical response remains challenging. Here, the propagating graphene plasmon provides an edge‐selective polaritonic probe to directly detect and control the electronic edge state at ambient condition. Compared with armchair, the edge‐band structure in the bandgap gives rise to additional optical absorption and strongly absorbed rim at zigzag edge. Furthermore, the optical conductivity is reconstructed and the anisotropic plasmon damping in graphene systems is revealed. The reported approach paves the way for detecting edge‐specific phenomena in other van der Waals materials and topological insulators.     

Lattice Dynamics,Phonon Chirality,and Spin–Phonon Coupling in 2D Itinerant Ferromagnet Fe3GeTe2

Fe₃GeTe₂ has emerged as one of the most fascinating van der Waals crystals due to its 2D itinerant ferromagnetism, topological nodal lines, and Kondo lattice behavior. However, lattice dynamics, chirality of phonons, and spin–phonon coupling in this material, which set the foundation for these exotic phenomena, have remained unexplored. Here, the first experimental investigation of the phonons and mutual interactions between spin and lattice degrees of freedom in few‐layer Fe₃GeTe₂ is reported. The results elucidate three prominent Raman modes at room temperature: two A_1g(Γ) and one E_2g(Γ) phonons. The doubly degenerate E_2g(Γ) mode reverses the helicity of incident photons, indicating the pseudoangular momentum and chirality. Through analysis of temperature‐dependent phonon energies and lifetimes, which strongly diverge from the anharmonic model below Curie temperature, the spin–phonon coupling in Fe₃GeTe₂ is determined. Such interaction between lattice oscillations and spin significantly enhances the Raman susceptibility, allowing to observe two additional Raman modes at the cryogenic temperature range. In addition, laser radiation‐induced degradation of Fe₃GeTe₂ in ambient conditions and the corresponding Raman fingerprint is revealed. The results provide the first experimental analysis of phonons in this novel 2D itinerant ferromagnet and their applicability for further fundamental studies and application development.     

Chiral esters: Sex pheromone of the bagworm,Oiketicus kirbyi (Lepidoptera: Psychidae)

Gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone extract of female bagworms,Oiketicus kirbyi (Guilding), revealed five EAD-active compounds. Retention index calculations, GC-mass spectrometry in both full-scan and selected-ion monitoring modes and GC-EAD analyses of authentic standards identified the compounds as 1-methylbutyl octanoate (MBO), 1-methylbutyl nonanoate (MBN), 1-methylbutyl decanoate (MBD), 1-methylpentyl decanoate (MPD), and 1-methylbutyl dodecanoate (MBDD). Of these five chiral esters, MBD was most abundant in extracts and elicited the strongest antennal response. In field experiments in Costa Rica, (R)-MBD attractedO. kirbyi males, whereas (S)-MBD in combination with (R)-MBD inhibited response.R but notS enantiomers of MBO, MBN, and MBDD strongly synergized attraction to (R)-MBD. (S)-MBO and (S)-MBDD were inactive, whereas (S)-MBN was inhibitory. (R)-, (S)- and racemic MPD were inactive. Blends of (R)-MBD in ternary combination with either (R)-MBO and (R)-MBN or (R)-MBN and (R)-MBDD were as attractive as the five-ester blend. Five- and four-ester blends were equally attractive, suggesting redundancy of pheromone components for attraction of males. The multiple sex pheromone component blend of chiral esters inO. kirbyi may have evolved to maintain species-specific communication in bagworm communities of tropical Americas.     

除草剂中的手性化合物

最近开发的除草剂的分子结构及其作用原理各式各样,而手性则是一种重要的普遍现象,它是这些除草剂分子的固有特性之一,对映选择性及对映特殊反应对于化合物活性与代谢作用是十分重要的问题,因为手性除草剂会引起植物的不同生理特性。本文讨论了重要的手性除草剂及不同反应、对映体选择性作用的相似性、手性与活性的相关性、对映体的代谢作用以及在禾本科植物分类中的不同手性反应。     

手性1-（2-吡啶基）-N-（2-吡啶甲基）乙胺的合成与表征

合成了一种新的三齿含氮手性化合物（R）or（S）-1-（2-吡啶基）-N-（2-吡啶甲基）乙胺（（R）or（S）-PEPM）,并通过NMR、MS、CD谱和光学纯度e．e值测定对其进行了表征．     

Male-specific volatiles from nearctic and Australasian true bugs (Heteroptera: Coreidae and Alydidae)

Aeration and exocrine gland extracts were analyzed for three Coreidae and two Alydidae. Males of all the species studied emit volatile blends that are probably pheromones, but sexual communication in these insects evolved differently. In the alydids,Riptortus serripes andMirperus scutellaris, the metathoracic scent glands are sexually dimorphic, and the dimorphisms are expressed chemically. Secretions from the male alydids contain high concentrations of esters or alcohols [e.g., (E)-2-hexenyl (Z)-3-hexenoate, (E)-2-hexenyl butyrate, and (E)-2-octenol], while females produce mainly acids and aldehydes [e.g., butyric and hexanoic acids, and (E)-2-hexenal]. In the coreids,Amblypelta lutescens lutescens, Amblypelta nitida, andLeptoglossus phyllopus, the metathoracic scent glands are not sexually dimorphic, but male- and species-specific volatiles are released, apparently from cells in the cuticular epidermis. The coreid male-specific volatiles are primarily monoterpenes and sesquiterpenes, including (–)-(3R)-(E)-nerolidol as the major component fromA. lutescens lutescens (an Australasian species) andL. phyllopus (a Nearctic species). Only (+)-(3S)-(E)-nerolidol is commonly found in plants so (E)-nerolidol from these coreids is environmentally unique because of its chirality.     

(S)-(+)-linalool,a mate attractant pheromone component in the bee Colletes cunicularius

Enantiomerically pure (S)-(+)-linalool was the main constituent in the extracts of the cephalic secretions of virgin females, mated females, freshly emerged males, and patrolling males of the solitary bee Colletes cunicularius. After copulation, the content of (S)-(+)-linalool emitted by the female was strongly reduced. Electrophysiological experiments revealed that both enantiomers of linalool elicited responses from the antennae of the males. Field tests using the pure enantiomers and the racemate of linalool showed that the number of male bees attracted was highest for (S)-(+)-linalool. The search flight activity in the mating flight area increased dramatically when patrolling males were presented with (S)-(+)-linalool vs (R)-(–)-linalool. Taken together, these data indicate a mate attractant pheromone function of (S)-(+)-linalool.     

Opposing Effects of Host Monoterpenes on Responses by Two Sympatric Species of Bark Beetles to Their Aggregation Pheromones

The effects of host tree monoterpenes on primary and secondary attraction of the bark beetles, Ips pini and Ips grandicollis, and their associated phloeophagous insects were investigated. Monoterpenes alone were not attractive to I. pini. However, monoterpenes mediated the attraction of I. pini to its aggregation pheromones. With the exception of 3–carene, the effect of monoterpenes on I. pini's response to its pheromone, ipsdienol plus lanierone, was inhibitory. In contrast, (–)--pinene both attracted I. grandicollis and enhanced the attraction of I. grandicollis to its pheromone, ipsenol. No monoterpene inhibited the response of I. grandicollis to its pheromone. The inhibitory effect of host monoterpenes on I. pini response to its aggregation pheromone differs from previous work, in which monoterpenes either synergized responses or had no effect. In addition to possible geographic differences, the concentrations used in our study simulated trees that had begun to respond to attack, whereas previous studies deployed lower concentrations, which simulated constitutive phloem from unattacked trees. These results support the view that trees that undergo induced responses to bark beetles sometimes inhibit attraction of additional beetles, despite the beetles' production of aggregation pheromones. Neither species displayed cross-attraction to the pheromone of the other. The red turpentine beetle, Dendroctonus valens, showed weak and consistent attraction to (+)--pinene and in some cases to (–)--pinene. Attraction to (–)--pinene was usually enhanced by Ips spp. pheromones. The absence of strong attraction to (+)--pinene and partial attraction to (–)--pinene suggest that the effects of different stereoisomers of -pinene on D. valens vary throughout its geographical range. Hylastes porculus was also attracted to some monoterpenes, particularly (–)--pinene. An additional 10 species of phloeophagous insects were caught in response to monoterpenes and/or pheromones, including the pine root weevils, Hylobius pales and Pachylobius picivorus, and the longhorned beetle, Monochamus carolinensis.     

A composite method for the determination of the chirality of single walled carbon nanotubes

An approach to the unambiguous determination of the conformation of individual single walled nanotubes utilizing high‐resolution transmission electron microscopy and digital image processing is described. The exit plane wave of single walled nanotubes restored from a focal series of images is used in a stepwise characterization procedure utilizing both the phase of the real space restoration and its Fourier transform. A combination of these complementary characterization steps yields an accurate measurement of the chiral vector for an individual nanotube.