On the role of the ablated mass on the propagation of a laser-generated plasma in an ambient gas

Abstract

We investigate the influence of the ablated mass on the dynamics of a laser-generated plasma expanding in an ambient gas. A laser-generated silver plasma expanding in argon was analysed by fast photo imaging. While keeping all relevant experimental parameters fixed, we changed the ablated mass per pulse, by changing the laser spot area at the target surface. We show that at fixed laser fluence, plasma dynamics undergoes dramatic changes as a function of the ablated mass per pulse. Plasma expansion dynamics is studied using drag, v 2 -drag, mixed propagation and Predtechensky-Mayorov models. Results show that, at a given laser fluence, when a shock wave forms, plasma dynamics is unequivocally determined by the ratio between the ablated mass per pulse and the gas density. Such a dynamics critically affects the kinetic energy at landing and the nanostructure resulting upon mutual assembling on the substrate of the deposited nanoparticles. Thus both the ablated mass per pulse and the laser fluence are to be known to control the nanostructure formation.

Functionalization of nanostructured gold substrates with chiral chromophores for SERS applications: The case of 5‐Aza[5]helicene

“…As expected with the adopted deposition conditions, the plasmon resonance of the present films is located at 840 nm (see Supporting Information). This fits the results of previous works where the correlation among morphology, plasmon resonance, and SERS response was carefully investigated . Hence, we focus the present study on the coupling of a representative helicene on such plasmonic surfaces.…”

“…This fits the results of previous works where the correlation among morphology, plasmon resonance, and SERS response was carefully investigated. 15,21,27,31,32 Hence, we focus the present study on the coupling of a representative helicene on such plasmonic surfaces. 5-Aza [5]helicene was prepared as previously reported 33 and endowed with a tail bearing a terminal double bond by means of heterocyclic aromatic substitution.…”

Catalytic Activity of Silicon Nanowires Decorated with Gold and Copper Nanoparticles Deposited by Pulsed Laser Ablation

“…Under the selected deposition conditions, the plasma expands through the ambient gas forming a shock wave [40], at the interface between the plasma and the atmosphere ambient. Gas density and pressure favor the in-flight formation of clusters that subsequently land onto the substrate surfaces.…”

Un Metodo Spettroscopico Per La Quantificazione Di Farmaci in Fluidi Biologici

“…Questa dipende, a parità di densità di energia depositata dall'impulso, dall'area su cui il fascio laser è focalizzato. Abbiamo studiato specificamente questo problema, considerando sia la propagazione della piuma, 22 sia la nanostruttura di superficie e le proprietà ottiche di un film. 23 Con impulsi che producono masse ablate in rapporto circa 1:2 (7.0 ng, M p ; 16.4 ng, M g ) si ottengono film di Ag morfologicamente simili, con nanostrutture a isole separate fra loro da canali di larghezza ed estensione variabili.…”