Commissioning and performance characterisation of a high-resolution laser ablation ionisation mass spectrometer
BORIS DOI
Abstract
Direct chemical analysis of solid material, especially of features with
dimensions in the micrometre scale, is of significant interest in a wide variety of
industrial and scientific fields. Capturing the chemical information of such features
requires specialised instrumentation capable of conducting analysis with high
spatial resolution, high sensitivity, and accurate quantification. This dissertation
presents the performance characterisation of the Laser Mass Spectrometer – Gran
Turismo (LMS–GT) instrument, a recently realised fs-Laser Ablation Ionisation Mass
Spectrometer capable of achieving mass resolution exceeding 10’000 m/ΔmFWHM.
An evaluation of the element analysis performance by developing
measurement procedures and data analysis routines tailored to the characteristics
of the LMS–GT was carried out. Applying these protocols to analyse metallic
standard reference materials (SRMs) showed that the LMS–GT is capable of
quantitative element analysis with high sensitivity. The achieved mass accuracy
facilitated confident identification of monatomic, polyatomic, and multiply charged
species, which led to accurate quantification of these species.
The use of UV laser radiation was found to be essential when analysing
dielectric materials. Identification and quantification of a wide range of trace
element isotopes with abundances down to single-digit ppb atomic fraction was
realised, while IR radiation only yielded detection of abundances at the percent level.
This denotes an improvement in detection limits of two orders of magnitude over
traditional LIMS instrumentation with UV radiation.
The next step in the performance evaluation involved isotope ratio analysis,
entailing the investigation of six different isotope systems spanning the full mass
range (i.e., from lithium to lead). The development of a robust data analysis
procedure tailored to data produced by LMS–GT is documented in this thesis. The
developed procedure yielded precisions below the per mill level, which is a
substantial improvement over commercially available LIMS instrumentation. After
correcting for observed instrument mass fractionation, lead isotope ratios were
derived with an accuracy below per mill, yielding uncertainties of ±10 Myrs in the
context of the Pb-Pb dating system.
Several technical developments on the hardware of the LMS–GT were realised
during this project, all aimed at improving its performance characteristics. The
implementation of a mass-selective beam blanking device let to a shift down by
almost two orders of magnitude in the investigated concentration range, facilitating
an improvement of detection limits of the same factor.
In summary, the results presented in this thesis show the tremendous potential
of the LMS–GT. The combination of performance metrics specific to the instrument
make it a valuable addition to the existing suite of quantitative microscale analytical
techniques. Improving the sensitivity, e.g., through post-ionisation of the ablation
plume, has the potential to push detection limits to parts-per-trillion, which would
allow the LMS–GT to occupy an analytical niche beyond what competing
techniques can achieve.
dimensions in the micrometre scale, is of significant interest in a wide variety of
industrial and scientific fields. Capturing the chemical information of such features
requires specialised instrumentation capable of conducting analysis with high
spatial resolution, high sensitivity, and accurate quantification. This dissertation
presents the performance characterisation of the Laser Mass Spectrometer – Gran
Turismo (LMS–GT) instrument, a recently realised fs-Laser Ablation Ionisation Mass
Spectrometer capable of achieving mass resolution exceeding 10’000 m/ΔmFWHM.
An evaluation of the element analysis performance by developing
measurement procedures and data analysis routines tailored to the characteristics
of the LMS–GT was carried out. Applying these protocols to analyse metallic
standard reference materials (SRMs) showed that the LMS–GT is capable of
quantitative element analysis with high sensitivity. The achieved mass accuracy
facilitated confident identification of monatomic, polyatomic, and multiply charged
species, which led to accurate quantification of these species.
The use of UV laser radiation was found to be essential when analysing
dielectric materials. Identification and quantification of a wide range of trace
element isotopes with abundances down to single-digit ppb atomic fraction was
realised, while IR radiation only yielded detection of abundances at the percent level.
This denotes an improvement in detection limits of two orders of magnitude over
traditional LIMS instrumentation with UV radiation.
The next step in the performance evaluation involved isotope ratio analysis,
entailing the investigation of six different isotope systems spanning the full mass
range (i.e., from lithium to lead). The development of a robust data analysis
procedure tailored to data produced by LMS–GT is documented in this thesis. The
developed procedure yielded precisions below the per mill level, which is a
substantial improvement over commercially available LIMS instrumentation. After
correcting for observed instrument mass fractionation, lead isotope ratios were
derived with an accuracy below per mill, yielding uncertainties of ±10 Myrs in the
context of the Pb-Pb dating system.
Several technical developments on the hardware of the LMS–GT were realised
during this project, all aimed at improving its performance characteristics. The
implementation of a mass-selective beam blanking device let to a shift down by
almost two orders of magnitude in the investigated concentration range, facilitating
an improvement of detection limits of the same factor.
In summary, the results presented in this thesis show the tremendous potential
of the LMS–GT. The combination of performance metrics specific to the instrument
make it a valuable addition to the existing suite of quantitative microscale analytical
techniques. Improving the sensitivity, e.g., through post-ionisation of the ablation
plume, has the potential to push detection limits to parts-per-trillion, which would
allow the LMS–GT to occupy an analytical niche beyond what competing
techniques can achieve.
Date of Publication
2023
Year of graduation
2023
Theses Type
dissertation
Subject(s)
Language(s)
en
Author(s)
Faculty/Graduate School
Institute
Access(Rights)
open.access
Primary OA Publication
true