Metal Nanoclusters for Optical Properties

Abstract

This chapter is focused on the use of ion beam processing for controlling the linear and nonlinear optical properties of different nanostructures based on metallic clusters embedded in silica. Three case studies will be presented: the first is the modification of the surface plasmon resonance of metallic nanoclusters by direct implantation or irradiation. The second is the far-field and local-field modification by means of controlled ion irradiation of bi-metallic nanoclusters. The last example deals with the synthesis of ordered plasmonic nanostructures using ion implantation and/or irradiation. These three examples are a sort of hierarchical approach to the control of the optical properties of nanostructures based on nanoparticles, starting from the synthesis of the functional building block of our approach, i.e. randomly positioned metal nanoparticles in silica, to end at the last level with the formation by ion implantation ordered arrays (chains or planar 2D assembly). In all these examples, ion implantation demonstrates to be not only a simple synthesis technique, but a very powerful processing tool for obtaining new functional properties. A brief description of the theoretical approach to the comprehension of the light-particle interaction from a semi-classical point of view will be given to aid the interpretation of the experimental results

Nonlinear optical properties of Au–Ag nanoplanets made by ion beam processing of bimetallic nanoclusters in silica

“…These have been attributed to the electromagnetic coupling between the core and the satellite nanoclusters, which affects the local field near the core surface [9]. Theoretical calculations have also revealed the formation of hot-spots with a local-field enhancement of about a factor 10 [4].…”

“…The MNCGs also exhibit interesting nonlinear optical (NLO) properties, related to the strong surface plasmon resonance in the visible spectrum, which make them very promising for molecular sensing applications and as ultrafast nonlinear optical elements [2][3][4][5][6].…”

“…On the other hand the functional properties of the nanostructures can be properly tuned by a tailored control of the irradiation parameters [2][3][4]. Recently, ion irradiation has been effectively employed to produce a new class of nanocluster structures named ''nanoplanets" (NPls), consisting of a central cluster surrounded by small satellites clusters [7].…”

Emission of photons from NaCl surface modified by silver at electronic bombardment

“…Враховуючи отримані залежності, а також результати мікроелементного аналізу зразків NaCl, який проводився на приладі ICP-MS Agilent 7900, можна припустити, що ЕФЕ чистого NaCl не пов'язана з домішками, а визначається утворенням і розпадом власних дефектів. Подібні дефекти створювалися і при іонному бомбардуванні ЛГК [15].…”

“…Отриманий спектральний розподіл за формою і положенням максимуму корелює з спектром колективних коливань електронної густини наночастинок срібла [3,15], які збуджуються електронним пучком. Перекриття спектру поверхневих плазмонів зі смугами ЕФЕ NaCl у видимому діапазоні свідчить про можливий обмін енергією електронного збудження між металевими частинками і дефектами матриці.…”