Mass spectrometric analysis of Mg-plasma produced by a double-pulse femtosecond laser irradiation

Tulej, Marek; Wiesendanger, Reto; Riedo, Andreas; Knopp, Gregor; Wurz, Peter (2018). Mass spectrometric analysis of Mg-plasma produced by a double-pulse femtosecond laser irradiation. Journal of analytical atomic spectrometry, 33(8), pp. 1292-1303. Royal Society of Chemistry 10.1039/c8ja00036k

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The capabilities of a double-pulse (DP) femtosecond (fs) laser ablation of solid materials as an ion source for the application in a miniature Laser ionisation time-of-flight Mass Spectrometer (LMS) system designed for space research are investigated. The studies are conducted by irradiating a high-purity Mg sample with sequences of two femtosecond laser pulses. The positively-charged fraction of the Mg plasma is analysed as function of the inter-pulse delay in the range from 0 to 300 ps and for pulse energies in the range from 0.2 to 1μJ. The DP ablation studies with both pulses of similar energy show the Mg+ ion yield enhancement within the inter-pulse delay range from 1 to 35 ps near the ablation energy threshold (AET) and from 1 to ~300 ps if larger pulse energies are applied for the first ablation pulse. For the same total energies but different individual pulse energies, the Mg+ ions are produced more efficiently if the weaker pulse is applied first. The analyses of the Mg+, multiply-charged Mg and Mg cluster ion yields as function of the inter-pulse delay and the pulse energies improve the understanding of the ablation mechanism and add some insights into dynamics of the Mg-surface melting and cooling phases, thermal characteristics of the expanding plasma plume and atomic/cluster ion production mechanisms. By applying sufficiently high DP energies > (0.3 + 0.3) μJ the clusters which are produced likely in the initial ablation phase at the surface can be decomposed effectively in the heated plasma plume. Moreover, by tuning the inter-pulse delay one can also efficiently suppress the neutral-ion reactions in post-plasma chemistry. Our studies show that the DP femtosecond laser ablation ion source can improve the mass spectrometric analysis of solid samples by increasing the ion yield of atomic ions and reducing the abundance of cluster ions. This can improve the quantitative analyses of elements and their isotopes by increasing signal-to-noise ratios and a reduction of isobaric interferences arising from cluster ions. The current DP studies are conducted successfully with pulse energies lower than 1 μJ, which is sufficiently low to be realised in a compact, lightweight system using fibre technology-based lasers, suitable for in-situ space application.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute

UniBE Contributor:

Tulej, Marek; Wiesendanger, Reto; Riedo, Andreas and Wurz, Peter

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science > 530 Physics

ISSN:

0267-9477

Publisher:

Royal Society of Chemistry

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

04 Jun 2018 14:23

Last Modified:

02 Aug 2018 01:31

Publisher DOI:

10.1039/c8ja00036k

BORIS DOI:

10.7892/boris.116945

URI:

https://boris.unibe.ch/id/eprint/116945

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