Femtosecond laser ablation inductively coupled plasma mass spectrometry: Fundamentals and capabilities for depth profiling analysis

Author(s): Jorge Pisonero, Detlef Günther

Abstract:

“Laser ablation coupled to inductively coupled plasma mass spectrometry has become a versatile and powerful analytical method for direct solid analysis. The applicability has been demonstrated on a wide variety of samples, where major, minor, and trace element concentrations or isotope ratio determinations have been of interest. The pros and cons of UV-nsec laser ablation have been studied in detail, and indicate that aerosol generation, aerosol transport, and aerosol excitation–ionization within the ICP contribute to fractionation effects, which prevent this method from a more universal application to all matrices and all elements. Recent progresses in IR-fs and UV-fs laser ablation coupled to ICP-MS have been reported, which increase the inter-matrix and multi-element quantification capabilities of this method. These fundamental improvements in LA-ICP-MS are of significant importance for entering new applications in material science and related research fields. In particular, because coatings (conducting and non-conducting) consist of single or multilayers of various elemental composition and of different thickness (nm–mm range), significant progress in the field of depth profiling with fs-laser ablation can be expected. Therefore, in-depth profile analysis of polymers, semiconductors, and metal sample investigations, using ultra-fast laser ablation for sampling and the currently achievable figures of merit, are discussed. In this review manuscript, the enhanced capabilities of fs-LA-ICP-MS for direct solid sampling are highlighted, and it is discussed about current methods used for quantitative analysis and depth profiling, the ablation process of UV-ns and UV-fs, the influence of the laser beam profile, aerosol structure and transport efficiency, as well as the influence of the ICP-MS (e.g., vaporization and ionization efficiency in the plasma, and type of mass analyzer).”

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Publication: Mass Spectrometry Reviews (subscription required)

Issue/Year/DOI: Mass Spectrometry Reviews, 2008, Volume 27, Issue 6, pages 609–623,
DOI: 10.1002/mas.20180

High throughput diffractive multi-beam femtosecond laser processing using a spatial light modulator

Author(s): Zheng Kuang, Walter Perrie, Jonathan Leach, Martin Sharp, Stuart P. Edwardson, Miles Padgett, Geoff Dearden and Ken G. Watkins

Abstract:

“High throughput femtosecond laser processing is demonstrated by creating multiple beams using a spatial light modulator (SLM). The diffractive multi-beam patterns are modulated in real time by computer generated holograms (CGHs), which can be calculated by appropriate algorithms. An interactive LabVIEW program is adopted to generate the relevant CGHs. Optical efficiency at this stage is shown to be ~50% into first order beams and real time processing has been carried out at 50 Hz refresh rate. Results obtained demonstrate high precision surface micro-structuring on silicon and Ti6Al4V with throughput gain >1 order of magnitude.”

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Publication: Applied Surface Science – via Science Direct (subscription required)

Issue/Year/DOI: Applied Surface Science, Volume 254 – 2008 (2008)
doi:10.1016/j.apsusc.2008.07.091

Oscillations and interactions of dark and dark–bright solitons in Bose–Einstein condensates

Author(s): Christoph Becker, Simon Stellmer, Parvis Soltan-Panahi, Sören Dörscher, Mathis Baumert, Eva-Maria Richter, Jochen Kronjäger, Kai Bongs & Klaus Sengstock

Abstract:

“Solitons are among the most distinguishing fundamental excitations in a wide range of nonlinear systems such as water in narrow channels, high-speed optical communication, molecular biology and astrophysics. Stabilized by a balance between spreading and focusing, solitons are wave packets that share some exceptional generic features such as form stability and particle-like properties. Ultracold quantum gases represent very pure and well-controlled nonlinear systems, therefore offering unique possibilities to study soliton dynamics. Here, we report on the observation of long-lived dark and dark–bright solitons with lifetimes of up to several seconds as well as their dynamics in highly stable optically trapped 87Rb Bose–Einstein condensates. In particular, our detailed studies of dark and dark–bright soliton oscillations reveal the particle-like nature of these collective excitations for the first time. In addition, we discuss the collision between these two types of solitary excitation in Bose–Einstein condensates.”

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Publication: Nature Physics, (free download)

Issue/Year/DOI: Nature Physics 4, 496 – 501 (2008)
doi:10.1038/nphys962

Spectral and temporal response of liquid-crystal-on-silicon spatial light modulators

Author(s): Martin Bock, Susanta Kumar Das, Ruediger Grunwald, Stefan Osten, Peter Staudt and Gero Stibenz

Abstract:

“Spectral and temporal phase response of selected types of liquid-crystal-on-silicon spatial light modulators were studied using femtosecond pulses, determining specific transfer functions of the devices. The phase response resulting from programed gray level distributions was detected by analyzing the diffraction characteristics and by spectral phase interferometry for direct electric-field reconstruction. The results indicate the appearance of distinct parameter ranges that enable minimum spatiotemporal distortion. Weak oscillations in the spectral phase are explained by Gires–Tournois resonances [F. Gires and P. Tournois, Acad. Sci. Paris, C. R. 258, 6112 (1964)].”

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Publication: Applied Physics Letters (subscription required)

Issue/Year/DOI: Appl. Phys. Lett. 92, 151105 (2008);
DOI:10.1063/1.2909115

Phase and amplitude pulse shaping with two-dimensional phase-only spatial light modulators

Author(s): Eugene Frumker and Yaron Silberberg

Abstract:

“We consider a programmable, phase, and amplitude femtosecond pulse shaper based on a two-dimensional (2D) reflective liquid-crystal (LC) spatial light modulator (SLM). A new zero-order pulse shaping scheme is introduced and compared to the first-order scheme, both theoretically and experimentally, using liquid crystal on silicon 2D SLM. While the spectral components of the pulse are spread across the horizontal dimension, we use the vertical direction for modulation of both spectral phases and amplitudes. It was found that while zero-order approach provided better light efficiency (67% versus 43%), the first-order scheme has superior dynamic range of amplitude modulation.”

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Publication: Journal of the Optical Society of America B, (subscription required)

Issue/Year/DOI: JOSA B, Vol. 24, Issue 12, pp. 2940-2947
doi:10.1364/JOSAB.24.002940

Ultrashort Laguerre-Gaussian pulses with angular and group velocity dispersion compensation

Author(s): I. Zeylikovich, H. I. Sztul, V. Kartazaev, T. Le, and R. R. Alfano

Abstract:

“Coherent optical vortices are generated from ultrashort 6.4 fs pulses. Our results demonstrate angular dispersion compensation of ultrashort 6.4 fs Laguerre-Gaussian (LG) pulses as well as what is believed to be the first direct autocorrelation measurement of 80 fs LG amplified pulses. A reflective-mirror-based 4f-compressor is proposed to compensate the angular and group velocity dispersion of the ultrashort LG pulses.”

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Publication: Optics Letters, (subscription required)

Issue/Year/DOI: Optics Letters, Vol. 32, Issue 14, pp. 2025-2027 (2007)
doi:10.1364/OL.32.002025

Depth Analysis of Polymer-Coated Steel Samples Using Near-Infrared Femtosecond Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Author(s): M. Paz Mateo, Carmen C. Garcia, R. Hergenröder

Abstract:

“The viability of near-infrared femtosecond laser ablation (fs-LA) inductively coupled plasma mass spectrometry (ICPMS) for the in-depth analysis of polymer coatings over galvanized steel substrates has been studied. A good depth resolution was obtained modifying the femtosecond Gaussian beam to a flat-top beam by using a liquid-crystal display. In order to avoid mixing of information coming from successive shots, a low repetition rate was accomplished and signals were monitored shot by shot. Different kinds of coatings were used to demonstrate the capability of femtosecond ablation for depth-profiling analysis. Ablation was conducted under He atmosphere, after sample cell Ar was admixed. The depth profiles obtained by LA-ICPMS are in good agreement with those obtained by GD-OES for the three analyzed samples. In cases where due to averaging over several millimeter sample roughness determines the depth resolution of GD-OES, it was found that LA-ICPMS achieves better depth resolution due to the better lateral resolution. The depth resolution obtained by LA-ICPMS was found to be 240 nm and 2.3 μm, for a hot-dip galvanized steel (HDGS) and a polymer−polymer-coated HDGS, respectively, compared to the 2.2 and 4.5 μm achieved with GD-OES for the same samples. ”

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Publication: Analytical Chemistry, (subscription required)

Issue/Year/DOI: Anal. Chem., 2007, 79 (13), pp 4908–4914
DOI: 10.1021/ac070241q

Femtosecond pulse shaping using a two-dimensional liquid-crystal spatial light modulator

Author(s): E. Frumker and Y. Silberberg

Abstract:

“We introduce a programmable, high-rate scanning femtosecond pulse shaper based on a two-dimensional liquid crystal on a silicon spatial light modulator (SLM). While horizontal resolution of 1920 addressable pixels provides superior fidelity for generating complex waveforms, scanning across the vertical dimension (1080 pixels) has been used to facilitate at least 3 orders of magnitude speed increase as compared with typical liquid-crystal SLM-based pulse shapers. An update rate in excess of 100 kHz is demonstrated.”

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Publication: Optics Letters, (subscription required)

Issue/Year/DOI: Optics Letters, Vol. 32, Issue 11, pp. 1384-1386 (2007)
doi:10.1364/OL.32.001384

Femtosecond laser ablation elemental mass spectrometry

Author(s): Roland Hergenröder, Ota Samek, Vanja Hommes

Abstract:

“Laser ablation mass spectrometry (LA-MS) has always been an interesting method for the elemental analysis of solid samples. Chemical analysis with a laser requires small amounts of material. Depending on the analytical detection system, subpicogram quantities may be sufficient. In addition, a focused laser beam permits the spatial characterization of heterogeneity in solid samples typically with micrometer resolution in terms of lateral and depth dimensions. With the advent of high-energy, ultra-short pulse lasers, new possibilities arise. The task of this review is to discuss the principle differences between the ablation process of short (>1 ps) and ultra-short (<1 ps) pulses. Based on the timescales and the energy balance of the process that underlies an ablation event, it will be shown that ultra-short pulses are less thermal and cause less collateral damages than longer pulses. The confinement of the pulse energy to the focal region guarantees a better spatial resolution in all dimensions and improves the analytical figures of merit (e.g., fractionation). Applications that demonstrate these features and that will be presented are in-depth profiling of multi-layer samples and the elemental analysis of biological materials." Link to Publications Page

Publication: Mass Spectrometry Reviews (subscription required)

Issue/Year/DOI: Mass Spectrometry Reviews, Volume 25, Issue 4 , Pages 551 – 572 (2005)
doi:10.1002/mas.20077

Femtosecond pulse shaping using a liquid–crystal display: Applications to depth profiling analysis

Author(s): Ota Samek, Vanja Hommes, Roland Hergenröder, Sergei V. Kukhlevsky

Abstract:

“We report on a beam shaping technique for femtosecond laser pulses based on a liquid-crystal display. The system is capable of modifying femtosecond Gaussian beams to a flattop beam. A pattern projected onto liquid-crystal display modifies the incoming Gaussian beam intensity so that flattop intensity profile is obtained. The process is monitored online using a charge-coupled device camera so that the intensity distribution of each pulse is known. An experimental example of the depth profile of a Cr layer on a Si substrate obtained using such a modified beam is presented.”

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Publication: Review of Scientific Instruments, (subscription required)

Issue/Year/DOI: Rev. Sci. Instrum. 76, 086104 (2005);
DOI:10.1063/1.1994897