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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/cm2) 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. [ABSTRACT FROM AUTHOR]

The electronic spectra of the C 3 H - and C 3 D - anions have been studied above the lowest electron detachment threshold. On the basis of the vibrational, rotational analysis and ab initio calculations, the photodetachment spectrum is assigned to the d 3 A″←a 3 A″ Feshbach resonance in the bent chain C 3 H(D) - anion. The vibronic system is characterized by a long vibrational progression involving the CCH in plane bending mode ν 4 . The potential curves along this coordinate obtained from the spectral analysis and theoretical calculations reveal the importance of vibronic coupling in the electronic excited states. A strong Renner-Teller effect is thought to be the reason for the existence of the Feshbach resonance because the 4 Σ - neutral parent and the 3 Π anion excited states are close in energy. As for the neutral, ν 4 appears to be the active mode and drives the interaction between the Feshbach and the dipole bound states. [ABSTRACT FROM AUTHOR]

The rotational structure of the origin band for the 1 A′← X 1 Σ + electronic transition, lying just below the electron affinity of C 4 H, was recorded by means of a two-colour resonant photodetachment technique. This allowed a determination of the rotational constants in the X 1 Σ + ground and 1 A′ dipole bound excited state. The low lying A 2 Π excited state of C 4 H is inferred to be the parent of the dipole bound state. The excited electronic state is deduced to have a nonlinear planar structure whereas the ground is linear according to the spectral analysis. The rotational constants have been obtained: B ″ = 0.1552(2) cm -1 for the X 1 Σ + state, and A ′ = 30.73(1), B ′ = 0.1587(2), C ′ = 0.1581(2) cm -1} for the 1 A′ state. [ABSTRACT FROM AUTHOR]

The electronic spectrum of the C[sub 3]H(D)¯ anion has been studied near the lowest electron detachment threshold associated with the chain isomer. On the basis of the vibrational and rotationalanalyses, the photodetachment spectrum is assigned to the [sup 3]A ′′ ← X[sup ~3]A ′′ electronic transition of the cumulene-like C[sub 3]H(D)¯ anion. Thespectrum is characterized by a rich vibrational structure leading to the determination of almost all fundamental frequencies. The vibrational progression involving the CCH(D) in plane bending mode (ν′[sub 6])is fitted with a 1-dimensional potential energy curve along the CCH(D) angle. This fit and the rotational analysis enable the geometry of the upper state to be determined. Although this excited state isexpected to have dipole bound character, its neutral counterpart has a significantly different structure. The observation of an excited triplet state near the electron detachment threshold and close tothe the calculated transition state for the electron catalysed isomerization reaction leads to new insight into this process. [ABSTRACT FROM AUTHOR]

The A [sup 2]Δ[sub u]←X [sup 2]Π[sub g], B [sup 2]Σ[sub u][sup -]←X [sup 2]Π[sub g], and C [sup 2]Σ[sub u][sup +]←X [sup 2]Π[sub g] electronic transitions of C[sub 3][sup -] were observed in a neon matrix and in the gas phase, although the energy of the excited electronic states involved in these transitions is 1-1.5 eV above the photodetachment threshold. The excited Feshbach states are sufficiently long-lived that some of the bands in the gas-phase photodetachment spectrum exhibit rotational structure. Assignment of the transitions is made on the basis of rotational analysis or profile simulations and theoretical calculations. The b [sup 4]Π[sub u]←X [sup 2]Π[sub g] transition is also weakly observed. The presence of such discrete bands, though in the continuum, provides a means of detection for anions in the interstellar medium. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This study aims to investigate the impact of the π → π* excitation localised in one monomer on the equilibrium geometry and oscillations of the AA dimer. Several low-frequency vibrations appear in pairs in the LIF spectrum because oscillations involving intermolecular hydrogen bonds are coupled, generating approximately symmetric and antisymmetric combinations (especially the COOH rocking modes, LIF: 295 and 301 cm -1 ). Furthermore, quantitative evaluation based on the TDDFT(B3LYP) results indicates that a dozen among 90 intramolecular oscillations are strongly coupled. In contrast, most vibrations are decoupled or weakly coupled, since they involve remote parts of the monomers. This makes several single vibrations active in the LIF spectrum (including the bending mode of the NH···O intramolecular hydrogen bond associated the strongest vibronic band 442 cm -1 ), while the other in each pair remains inactive. The reason for decoupling of oscillations and symmetry breaking is that the π → π* electronic excitation is entirely localised within one of the monomers, which makes them no longer equivalent in terms of geometry and dynamics. Additionally, the excitation of one monomer induces strengthening and shortening by 6 pm of only one intermolecular hydrogen bond linking the carboxylic groups of both molecules. This causes the 1.7° in-plane distortion of the dimer and lowering of its symmetry to C s group (from C 2 h for the S 0 state). The distortion induces the activity of two low-frequency in-plane intermolecular vibrations, i.e. the geared oscillation (LIF: 58 cm -1 ) and the shearing motion (99 cm -1 ) of the monomers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In femtosecond Laser Ablation Ionisation Mass Spectrometry (fs-LIMS) short laser pulses are used to ablate, atomise, and ionise solid sample material shot-by-shot. When ablating non-conductive samples electric charging of the surface can occur. Depending on the geometry of the instrument, the surface charge can influence the spread of the ablation plume and reduce spectral quality. Methods to reduce surface charging were investigated using a non-conductive geological sample and a miniature fs-LIMS system with a co-linear ablation geometry. Pausing five seconds between consecutive laser bursts fired on non-coated material improved the spectral quality by giving surface charges more time to dissipate. However, best mass spectrometric results were achieved after the sample was sputter coated with a thin gold layer, as a conductive sample surface hinders charge build-up. Consequently, gold coating allowed operation of the laser system at much higher laser pulse energies improving sensitivity and reliability. It also removed the need to pause between laser bursts, speeding up the measurement acquisition., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Laser ablation is nowadays an extensively applied technology to probe the chemical composition of solid materials. It allows for precise targeting of micrometer objects on and in samples, and enables chemical depth profiling with nanometer resolution. An in-depth understanding of the 3D geometry of the ablation craters is crucial for precise calibration of the depth scale in chemical depth profiles. Herein we present a comprehensive study on laser ablation processes using a Gaussian-shaped UV-femtosecond irradiation source and present how the combination of three different imaging methods (scanning electron microscopy, interferometric microscopy, and X-ray computed tomography) can provide accurate information on the crater's shapes. Crater analysis by applying X-ray computed tomography is of considerable interest because it allows the imaging of an array of craters in one step with sub-µm accuracy and is not limited to the aspect ratio of the crater. X-ray computed tomography thereby complements the analysis of laser ablation craters. The study investigates the effect of laser pulse energy and laser burst count on a single crystal Ru(0001) sample. Single crystals ensure that there is no dependence on the grain orientations during the laser ablation process. An array of 156 craters of different dimensions ranging from <20 nm to ∼40 µm in depth were created. For each individually applied laser pulse, we measured the number of ions generated in the ablation plume with our laser ablation ionization mass spectrometer. We show to which extent the combination of these four techniques reveals valuable information on the ablation threshold, the ablation rate, and the limiting ablation depth. The latter is expected to be a consequence of decreasing irradiance upon increasing crater surface area. The ion signal generated was found to be proportional to the volume ablated up to the certain depth, which enables in-situ depth calibration during the measurement.

The investigation of chemical composition on planetary bodies without significant sample processing is of importance for nearly every mission aimed at robotic exploration. Moreover, it is a necessary tool to achieve the longstanding goal of finding evidence of life beyond Earth, for example, possibly preserved microbial remains within martian sediments. Our Laser Ablation Ionization Mass Spectrometer (LIMS) is a compact time-of-flight mass spectrometer intended to investigate the elemental, isotope, and molecular composition of a wide range of solid samples, including e.g., low bulk density organic remains in microfossils. Here, we present an overview of the instrument and collected chemical spectrometric data at the micrometer level from a Precambrian chert sample (1.88 Ga Gunflint Formation, Ontario, Canada), which is considered to be a martian analogue. Data were collected from two distinct zones-a silicified host area and a carbon-bearing microfossil assemblage zone. We performed these measurements using an ultrafast pulsed laser system (pulse width of ∼180 fs) with multiple wavelengths (infrared [IR]-775 nm, ultraviolet [UV]-387 nm, UV-258 nm) and using a pulsed high voltage on the mass spectrometer to reveal small organic signals. We investigated (1) the chemical composition of the sample and (2) the different laser wavelengths' performance to provide chemical depth profiles in silicified media. Our key findings are as follows: (1) microfossils from the Gunflint chert reveal a distinct chemical composition compared with the host mineralogy (we report the identification of 24 elements in the microfossils); (2) detection of the pristine composition of microfossils and co-occurring fine chemistry (rare earth elements) requires utilization of the depth profiling measurement protocol; and (3) our results show that, for analysis of heterogeneous material from siliciclastic deposits, siliceous sinters, and cherts, the most suitable wavelength for laser ablation/Ionization is UV-258 nm.

In this contribution, we present results of non-linear dimensionality reduction and classification of the fs laser ablation ionization mass spectrometry (LIMS) imaging dataset acquired from the Precambrian Gunflint chert (1.88 Ga) using a miniature time-of-flight mass spectrometer developed for in situ space applications. We discuss the data generation, processing, and analysis pipeline for the classification of the recorded fs-LIMS mass spectra. Further, we define topological biosignatures identified for Precambrian Gunflint microfossils by projecting the recorded fs-LIMS intensity space into low dimensions. Two distinct subtypes of microfossil-related spectra, a layer of organic contamination and inorganic quartz matrix were identified using the fs-LIMS data. The topological analysis applied to the fs-LIMS data allows to gain additional knowledge from large datasets, formulate hypotheses and quickly generate insights from spectral data. Our contribution illustrates the utility of applying spatially resolved mass spectrometry in combination with topology-based analytics in detecting signatures of early (primitive) life. Our results indicate that fs-LIMS, in combination with topological methods, provides a powerful analytical framework and could be applied to the study of other complex mineralogical samples., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Lukmanov, Riedo, Wacey, Ligterink, Grimaudo, Tulej, de Koning, Neubeck and Wurz.)