Graphite surface microscopic image and valence band structure together with atomic structure models: Fumihiko Matsui, Institute for Molecular Science in Okazaki, Japan.<\/figcaption><\/figure>\nPhotoelectron momentum-resolved spectro-microscopy<\/h3>\n In the worst case, this conventional measurement technique can lead to ignoring surface states and misinterpretation of bulk-specific electronic properties. Using a technique called photoelectron momentum-resolved spectro-microscopy, researchers examined the electronic structures of graphite\u2019s surface. Through this, they were able to see how the surface states interacted with the bulk bands and succeeded in imaging single-atom height steps on a graphite surface.\u00a0 Understanding both the surface state and band structures of graphite can help researchers understand its electrical properties as well.<\/p>\n
Graphite is a crystalline form of carbon that is made up of many layers. Each individual layer of graphite, called graphene, is structured in a hexagonal honeycomb. The way these layers stack on top of each other affects the type of electronic band structures that are found in the graphite.<\/p>\n
\u201cGraphite crystals with an\u00a0ABAB-<\/em>type stacking structure are six-fold symmetric around the\u00a0z-axis<\/em>, whereas a surface with one type of termination is three-fold symmetric,\u201d explained Matsui. When researchers looked at the dispersion of the\u00a0kz<\/sub>\u00a0<\/em>band at the micrometre-scale, they discovered that the combination of this six-fold structure and the three-fold structure eliminated the degeneracy of the \u03c0 band and the symmetry was reduced.<\/p>\nGraphite surface geometry with broken symmetry<\/h3>\n \u201cIn this study, we have succeeded in characterising the effect of such a coupling in a surface geometry with broken symmetry,\u201d said Matsui. \u201cThe observed bulk dispersion differs from the discrete electronic states of several layers of graphene, meaning that the measurement is also sensitive to the bulk electronic states from much deeper than the mean free path length of the emitted electrons. Moreover, the\u00a0kz<\/sub>\u00a0<\/em>dispersion bandwidth is affected by the coupling with the surface electronic state, as shown in this study. The accuracy and resolution of\u00a0kz<\/sub>\u00a0<\/em>dispersion bandwidth determination are limited by the electron attenuation length, especially when the surface resonance state couples with the bulk\u00a0kz<\/sub>–<\/em>dispersed band.\u201d<\/p>\nLooking ahead, more theoretical research is required to understand how these different structures work together. \u201cFurther theoretical studies of valence photoelectron emission with precise consideration of the surface effect are desired in order to clarify the\u00a0kz<\/sub><\/em>\u00a0intensity dependence,\u201d concluded Matsui.<\/p>\n","protected":false},"excerpt":{"rendered":"Researchers from the Institute for Molecular Science in Okazaki, strive to understand the electronic structure of graphite by analysing its surface state using a newly developed photoelectron spectroscopy machine combined with an electron microscope. Graphite is an incredibly important, versatile mineral, with uses spanning across many different industries. Because graphite can easily conduct electricity and […]<\/p>\n","protected":false},"author":19,"featured_media":23462,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[24429],"tags":[649,24335,24207],"acf":[],"yoast_head":"\n
Researchers improve understanding of the electronic structure of graphite<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n \n \n \n \n \n\t \n\t \n\t \n