Time-resolved angular distributions of plume ions from silver at low and medium laser fluence

Bo Toftmann Christensen, Jørgen Schou

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Abstract

Even at moderate fluence (0.6 -2.4 J/cm2) laser impact on metals in the UV regime results in a significant number of ions emitted from the surface. The ablated particles are largely neutrals at the lowest fluence, but the fraction of ions increases strongly with fluence. We have irradiated silver in a vacuum chamber (~ 10-7 mbar) with a Nd:YAG laser at a wavelength of 355 nm and made detailed measurements of the time-resolved angular distribution. The ion flow in different directions has been measured with a hemispherical array of Langmuir probes, by which the time-of-flight spectra, as well as the total angular yield, in all directions can be recorded (1). The angular distribution peaks more strongly in forward direction with increasing fluence - as also reported in the literature – and can be well approximated by the model of Anisimov et al. (1,2). Typically, the spectra of silver ions peak from 70 eV up to 145 eV in a direction normal to the target surface with increasing fluence. With increasing observation angle the time-of-flight spectra exhibit a peak at longer flight times, i.e. at a lower kinetic energy. At the highest fluence the ionized fraction of the ablated particles exceeds 0.5.
Original languageEnglish
Publication date2011
Publication statusPublished - 2011
Event11th International Conference on Laser Ablation - Playa del Carmen, Mexico
Duration: 13 Nov 201119 Nov 2011
Conference number: 11
http://www.cola11.org/

Conference

Conference11th International Conference on Laser Ablation
Number11
CountryMexico
CityPlaya del Carmen
Period13/11/201119/11/2011
Internet address

Cite this

Christensen, B. T., & Schou, J. (2011). Time-resolved angular distributions of plume ions from silver at low and medium laser fluence. Abstract from 11th International Conference on Laser Ablation, Playa del Carmen, Mexico. http://www.cola11.org/