Cathodoluminescence and optical absorption spectroscopy of plasmonic modes in chromium micro-rods. (12th February 2023)

• Record Type: Journal Article
• Authors: Ghorai, Gurupada; Ghosh, Kalyan; Das, Bidyadhar; Sahoo, Subhashree; Patra, Bikash; Samal, Prasanjit; Sahoo, Pratap K
• Is Part Of: Nanotechnology. Volume 34:Number 7(2023)
• Publication Date: 2023-02-12
• Subjects: cathodoluminescence -- absorption spectroscopy -- Au -- Cr -- plasmonics; Nanotechnology -- Periodicals; Nanotechnology -- Periodicals; Nanotechnology; Publications périodiques; Nanotechnologies; Periodicals; 620.5
• DOI: 10.1088/1361-6528/aca339
• Languages: English
• ISSNs: 0957-4484

Abstract

Abstract: Manipulating light at the sub-wavelength level is a crucial feature of surface plasmon resonance (SPR) properties for a wide range of nanostructures. Noble metals like Au and Ag are most commonly used as SPR materials. Significant attention is being devoted to identify and develop non-noble metal plasmonic materials whose optical properties can be reconfigured for plasmonic response by structural phase changes. Chromium (Cr) which supports plasmon resonance, is a transition metal with shiny finished, highly non-corrosive, and bio-compatible alloys, making it an alternative plasmonic material. We have synthesized Cr micro-rods from a bi-layer of Cr/Au thin films, which evolves from face centered cubic to hexagonal close packed (HCP) phase by thermal activation in a forming gas ambient. We employed optical absorption spectroscopy and cathodoluminescence (CL) imaging spectroscopy to observe the plasmonic modes from the Cr micro-rod. The origin of three emission bands that spread over the UV–Vis-IR energy range is established theoretically by considering the critical points of the second-order derivative of the macroscopic dielectric function obtained from density functional theory (DFT) matches with interband/intraband transition of electrons observed in density of states versus energy graph. The experimentally observed CL emission peaks closely match the s – d and d – d band transition obtained from DFT calculations. Our findings on plasmonic modes in Cr(HCP) phase can expand the range of plasmonic material beyond noble metal with tunable plasmonic emissions for plasmonic-based optical technology.