Search

The recognition of biosignatures on planetary bodies requires the analysis of the putative microfossil with a set of complementary analytical techniques. This includes localized elemental and isotopic analysis of both, the putative microfossil and its surrounding host matrix. If the analysis can be performed with spatial resolution at the micrometer level and ppm detection sensitivities, valuable information on the (bio)chemical and physical processes that influenced the sample material can be gained. Our miniaturized laser ablation ionization mass spectrometry (LIMS)-time-of-flight mass spectrometer instrument is a valid candidate for performing the required chemical analysis in situ. However, up until now it was limited by the spatial accuracy of the sampling. In this contribution, we introduce a newly developed microscope system with micrometer accuracy for Ultra High Vacuum application, which allows a significant increase in the measurement capabilities of our miniature LIMS system. The new enhancement allows identification and efficient and accurate sampling of features of micrometer-sized fossils in a host matrix. The performance of our system is demonstrated by the identification and chemical analysis of signatures of micrometer-sized fossil structures in the 1.9 billion-year-old Gunflint chert.

Rationale: There is an increasing interest in the quest for low molecular weight biomarkers that can be studied on extra-terrestrial objects by direct laser desorption mass spectrometry (LD-MS). Although molecular structure investigations have recently been carried out by direct LD-MS approaches, there is still a lack of suitable instruments for implementation on a spacecraft due to weight, size and power consumption demands. In this contribution we demonstrate the feasibility of LD-MS structural analysis of molecular species by a miniature laser desorption-ionization mass spectrometer (instrument name LMS) originally designed for in situ elemental and isotope analysis of solids in space research., Methods: Direct LD-MS studies with molecular resolution were carried out by means of a Laser Ablation/Ionization Mass Spectrometry (LIMS) technique. Two polymer samples served as model systems: neutral polyethylene glycol (PEG) and cationic polymerizates of imidazole and epichlorohydrin (IMEP). Optimal conditions for molecular fragmentation could be identified for both polymers by tuning the laser energy and the instrument-sample distance., Results: PEG and IMEP polymers show sufficient stability over a relatively wide laser energy range. Under mild LD conditions only moderate fragmentation of the polymers takes place so that valuable structural characterization based on fragment ions can be achieved. As the applied laser pulse energy rises, the abundance of fragment ions increases, reaches a plateau and subsequently drops down due to more severe fragmentation and atomization of the polymers. At this final stage, usually referred to as laser ablation, only elemental/isotope analysis can be achieved., Conclusions: Our investigations demonstrate the versatility of the LMS instrument that can be tuned to favourable laser desorption conditions that successfully meet molecule-specific requirements and deliver abundant fragment ion signals with detailed structural information. Overall, the results show promise for use in similar studies on planetary surfaces beyond Earth where no or minimal sample preparation is essential., (Copyright © 2016 John Wiley & Sons, Ltd.)

Key performance features of a miniature laser ablation time-of-flight mass spectrometer designed for in situ investigations of the chemical composition of planetary surfaces are presented. This mass spectrometer is well suited for elemental and isotopic analysis of raw solid materials with high sensitivity and high spatial resolution. In this study, ultraviolet laser radiation with irradiances suitable for ablation (< 1 GW/cm(2)) is used to achieve stable ion formation and low sample consumption. In comparison to our previous laser ablation studies at infrared wavelengths, several improvements to the experimental setup have been made, which allow accurate control over the experimental conditions and good reproducibility of measurements. Current performance evaluations indicate significant improvements to several instrumental figures of merit. Calibration of the mass scale is performed within a mass accuracy (Δm/m) in the range of 100 ppm, and a typical mass resolution (m/Δm) ~600 is achieved at the lead mass peaks. At lower laser irradiances, the mass resolution is better, about (m/Δm) ~900 for lead, and limited by the laser pulse duration of 3 ns. The effective dynamic range of the instrument was enhanced from about 6 decades determined in previous study up to more than 8 decades at present. Current studies show high sensitivity in detection of both metallic and non-metallic elements. Their abundance down to tens of ppb can be measured together with their isotopic patterns. Due to strict control of the experimental parameters, e.g. laser characteristics, ion-optical parameters and sample position, by computer control, measurements can be performed with high reproducibility., (Copyright © 2012 John Wiley & Sons, Ltd.)

Sn solder bumps on Cu pillars and the quantification of incorporated organic impurities are of urgent interest to the microchip industry. In this report, the fundamentals of laser–matter interaction using femtosecond laser ablation ionization mass spectrometry (fs-LIMS) are described, including studies on the ablation rate of a dual layer system Sn/Cu as well as on three different laser ablation approaches that (i) address the highly different material properties of Sn and Cu and (ii) allow for a significant reduction of side-wall contributions, which is a crucial prerequisite for chemical depth profiling. [ABSTRACT FROM AUTHOR]

Detectors of scientific instruments on spacecraft flying through Jupiter radiation belts need to be protected from high fluxes of penetrating radiation by means of radiation shields. Electrons constitute the most difficult component of Jupiter’s magnetosphere to shield from, because of their abundance, penetration depth in matter, and intensity of bremsstrahlung radiation generated upon interaction with the shielding material. For the Neutral and Ion Mass spectrometer (NIM) of the Particle Environment Package (PEP) instrument suite on board the European Space Agency’s mission JUpiter Icy moons Explorer (JUICE), we devised a shielding design made of an aluminum and tantalum stack to reduce the radiation-induced noise on its Micro-Channel Plate (MCP) detector. To predict the expected radiation background in the mass spectra in space, we manufactured a flight-like shielded detector and submitted it to radiation testing at the Paul Scherrer Institut with an electron beam in the energy range ~ 30 to ~ 345 MeV. The results of this test provide a verification of the NIM capability to fulfill its science requirements in the mission’s worst-case scenario (the Europa flyby), and give insights into new directions of optimization of shielding elements’ design for NIM and similar instrument bound to operate in a harsh radiation environment. [ABSTRACT FROM PUBLISHER]

Laser ablation ionization mass spectrometry studies on polished surface structures of hard, high melting point multicomponent interconnect structures using our femtosecond-laser time-of-flight mass spectrometer have previously been proven capable of providing spatially resolved chemical depth profile data at the micro- and nanometer level. Transfer of experimental protocols tailored to suit such type of samples to low melting point materials with high surface roughness, however, is highly challenging, as thermal effects caused by interactions of the laser light with the targeted surface play a severe role in the latter case and may significantly deteriorate the analysis outcome. In this contribution we present a dedicated and detailed comparison of the distinct effects of near infrared and ultraviolet irradiation on the ablation process in femtosecond laser ablation ionization mass spectrometry studies on low melting point materials. As model substrate we use high surface roughness, as-deposited SnAg solder alloy, a material of major industrial relevance in microchip fabrication. We will demonstrate herein that polydimethylsiloxane replica casting is possible also from granularly structured, high surface roughness samples. Characterization of the laser ablation craters as well as of their polydimethylsiloxane replicas is carried out by mass spectrometric analysis, Scanning Electron Microscopy imaging, and furthermore, as a novel approach for this purpose, by white light interferometry. Integration of all obtained results significantly adds to the detailed understanding of laser ablation processes on low melting point, high surface roughness materials and allows identifying optimal depth profiling conditions for these demanding samples. [Display omitted] • Laser ablation studies on technologically highly relevant SnAg bump. • Measurement procedure for low melting point, high surface roughness, solder alloys. • Demonstration of improved fs-LIMS capabilities by moving from NIR to UV irradiation. • UV reduces thermal effects, increases ablation rate and decreases the crater size. • UV laser ablation provides better shot-to-shot stability of the ablation process. [ABSTRACT FROM AUTHOR]