Redshift of Quantum-Particle Plasmon Stemming from Thermal-Induced Quantum Size Effects: Numerical Modeling and Experimental Evidence

Abstract

Work is reported on thermal-induced redshifts of quantum particle plasmon. The redshifts are predicted to be caused indirectly by the quantum size effects. The particles are enlarged when temperature increases, and consequently, quantum size effects modify the plasmon but not the band structure. It has been modeled for metallic quantum particles. The results are also instructive to other quantum systems, such as complex molecules. Every electron inside the quantum particle is taken into account. Tiny quantum size effects are harvested, and the redshift becomes significant. What is shifted is the so-called small particle plasmon frequency, which stems from collective intraband transitions of electrons. Interband transitions are excluded from the plasmonics. Therefore, the band structure is intact from the onset. Experimental observation is also reported for the spectral redshift. Faujasite zeolites were synthesized. Optical spectroscopy has been carried out, and the resulting spectra showed a significant redshift with the increase in temperature. The experimental observation provides early phenomenological evidence for the spectral redshift predicted by our theoretical model calculations.

Received: 18 April 2025 | Revised: 13 June 2025 | Accepted: 23 June 2025

Conflicts of Interest

The authors declare that they have no conflicts of interest to this work.

Data Availability Statement

Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Author Contribution Statement

Mufei Xiao: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration, Funding acquisition. Constanza Koop-Santa: Validation, Formal analysis, Investigation, Resources, Data curation. Nikifor Rakov: Validation, Formal analysis, Investigation, Resources, Data curation.