Tunability of Surface Plasmon Resonance Peaks in CsI:Ag Films by Growth Conditions
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Tunability of Surface Plasmon Resonance Peaks in CsI:Ag Films by Growth Conditions Lovkush 1 & Chhaya Ravi kant 2 & P. Arun 3 Received: 13 May 2019 / Accepted: 1 November 2019 # Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract The manuscript reports the optical, structural, and morphological properties of thin films of CsI:Ag composites fabricated under various conditions by thermal evaporation method on glass substrates. The absorption spectra of these films show strong surface plasmon resonance (SPR) absorption peak/s. In samples with spherical silver nanoparticles, position of SPR peaks revealed red shift that was due to the increase the particle size of silver. Also, appearance of a new SPR peak was detected towards higher wavelengths due to the proximity effect, i.e., due to decrease in the interparticle distance between the silver nanoparticles. In contrast, the thin films with silver nanorods exhibited typical two SPR peaks assigned to higher and lower frequencies of visible spectrum. The aspect ratio of the nanorods showed an increasing trend with increase in film thickness. Results of this manuscript show how to achieve tunability of SPR peaks by varying the growth condition and film thickness. Keywords Nanocomposite film . Particle-particle separation . Surface plasmon resonance . Silver nanorods
Introduction Plasmonics is a branch of photonics which is a growing at a rapid pace and is an emerging field dealing with EM radiation interacting at the metal/dielectric interface [1–4]. Many researchers have shown their interest in plasmonic nanoparticles, such as silver and gold nanoparticles, because of their potential applications. The free electrons of conduction band at the surface of the metal are set in oscillation due to the interaction with EM radiation. These free electrons are localized to some specific vibration modes due to the nanoparticle morphology [5, 6]. A strong absorption occurs due to this oscillation resonating with the incident EM frequency. This is known as surface plasmon resonance (SPR) [7–9]. SPR is evident when the metal particles have at least one dimension in the nanoscale [10–13] or size of the order of the wavelength of incident radiation [14–17]. The enhancement of the light * Chhaya Ravi kant [email protected] 1
University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, Delhi 110078, India
2
Department of Applied Sciences and Humanities, Indira Gandhi Delhi Technical University for Women, Delhi 110006, India
3
Department of Electronics, SGTBK College, University of Delhi, Delhi 110007, India
absorption due to surface plasmon is useful in many optical devices, e.g., optical filter [18], solar cell [19], SERS [20], and optical data storage [21]. The reason for silver and gold’s popularity is their low rate of scattering by their free electrons, which in turn gives high conductivity in the radiofrequency range and high reflectivity in the optical range [22]. However, as explained by Krugin [22],
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