Maritime Department, University of Zadar, M. Pavlinovića 1, 23000 Zadar, Croatia.
Department of Atomic Physics, "VINČA" Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, P.O. Box 522, 11001 Belgrade, Serbia.
Int J Mol Sci. 2022 Apr 26;23(9):4770. doi: 10.3390/ijms23094770.
Graphene doped by alkali atoms (ACx) supports two heavily populated bands (π and σ) crossing the Fermi level, which enables the formation of two intense two-dimensional plasmons: the Dirac plasmon (DP) and the acoustic plasmon (AP). Although the mechanism of the formation of these plasmons in electrostatically biased graphene or at noble metal surfaces is well known, the mechanism of their formation in alkali-doped graphenes is still not completely understood. We shall demonstrate that two isoelectronic systems, KC8 and CsC8, support substantially different plasmonic spectra: the KC8 supports a sharp DP and a well-defined AP, while the CsC8 supports a broad DP and does not support an AP at all. We shall demonstrate that the AP in an ACx is not, as previously believed, just a consequence of the interplay of the π and σ intraband transitions, but a very subtle interplay between these transitions and the background screening, caused by the out-of-plane interband C(π)→A(σ) transitions.
碱原子掺杂的石墨烯（ACx）支持两个高度占据的能带（π 和 σ）穿过费米能级，这使得能够形成两个强烈的二维等离子体：狄拉克等离子体（DP）和声学等离子体（AP）。尽管静电偏压石墨烯或贵金属表面上这些等离子体的形成机制已经很清楚，但在碱掺杂石墨烯中它们的形成机制仍不完全清楚。我们将证明两个等电子体系 KC8 和 CsC8 支持截然不同的等离子体光谱：KC8 支持尖锐的 DP 和明确的 AP，而 CsC8 则完全支持宽 DP 而不支持 AP。我们将证明 AP 在 ACx 中并不像以前认为的那样，只是π和 σ 带内跃迁相互作用的结果，而是这些跃迁与由平面外 C(π)→A(σ)跃迁引起的背景屏蔽之间的非常微妙的相互作用。
