Ag nanocluster synthesis by laser ablation in Ar atmosphere: A plume dynamics analysis

Abstract

Ag thin films were deposited by pulsed laser ablation in a controlled Ar atmosphere. The deposition process was performed at different Ar pressure values in the range between 10 and 100 Pa to investigate the influence of ambient gas pressure on the plasma expansion dynamics and on the film structural properties. Position, velocity and volume of the laser generated plasma as functions of time were obtained by time resolved fast photography. The morphological properties of the films were investigated by transmission electron microscopy which shows that film growth proceeds via aggregation on the substrates of nanoclusters formed in the expanding plume. The formation of nanoparticles takes place as a consequence of plasma confinement induced by the interaction with ambient gas species. Data from fast photography analysis were used as input parameters to calculate the size of the nanoparticles using a model that takes into account the collisional nature of the laser generated silver plasma.

Ag and Au nanoparticles for SERS substrates produced by pulsed laser ablation

“…(* pg is the Ar pressure, ng is the number density of Ar gas atoms, na is the average number density of ablated atoms, σa-g and σa-a are the geometric cross-sections for ablated particle -ablated particle and for ablated particle -gas atom binary collisions respectively, ν0 is the initial plasma velocity, <ν> is the average velocity of plume particles, tf is the cluster formation time, xaggr is the distance travelled by the plume during cluster growth, d and <d> are the nanoparticle sizes theoretical and experimental respectively.) In order to verify our observation, theoretical calculations were done based on modelling of plasma expansion [15,16,18]. For this, images obtained by the fast imaging iCCD camera were introduced to MATLAB.…”

“…Thus, by controlling the operation conditions, production of highly sensitive substrates to produce a SERS spectrum can be obtained [17,18]. Ablation of target materials (either Ag or Au) was done in an Ar atmosphere at varying pressures using a nanosecond laser to obtain a plasma plume that is deposited on the substrate to give rise to a distinct nanostructure patterned substrate [14].…”

“…These images were transformed into useful data to calculate the initial velocity of the plume. This data along with the measured average mass per pulse were taken as inputs to the mixed propagation model to calculate the average sizes of the nanoparticles that are obtained on the substrate [15,16,18]. These calculated data of nanoparticle sizes at various pressures of Argon for Au are reported in table 1.…”

“…The important criterion for SERS is that the substrate surface has to be a roughened feature [10,11] since the magnitude of SERS not only depends on nanoparticle dimensions but also the size, shape, spatial density and distribution of these nanoparticles [12,13]. We propose a method of production of such excellent featured substrates using Pulsed Laser Ablation (PLD) based on Bottom Up approach [14][15][16][17][18].…”

Ion jet generation in the ultraintense laser interactions with rear-side concave target

“…The advent of ultrashort ultraintense laser pulses led to the development of new exciting fields in laser plasma interaction (Karsch et al, 1999;Malka et al, 2004;Roth et al, 2005;Mangles et al, 2006;Kawata et al, 2005;Yu et al, 2005;Glowacz et al, 2006;Koyama et al, 2006;Lifshitz et al, 2006;Sakai et al, 2006;Yu et al, 2007;Hora, 2007;Dromey et al, 2009;Fazio et al, 2009;Hoffmann 2008aHoffmann , 2008bKasperczuk et al, 2009aKasperczuk et al, , 2009bLaska et al, 2007;Limpouch et al, 2008;Malekynia et al, 2009;Sharma & Sharma 2009;Izgorodin et al, 2009;Li et al, 2009;Sadighi-Bonabi et al, 2009;Hong et al, 2009;Kline et al, 2009). The generation of energetic ion beams from laser plasma interaction is an exciting area of research with important applications ranging from medical proton therapy (Bulanov & Khoroshkov, 2002), high-energydensity physics (Patel et al, 2003), to fast ignition in inertial confinement fusion .…”