Quantitative surface composition analysis using very high intensity nonresonant multiphoton ionization

He, Chun; Basler, Julian N.; Paul, A.; Becker, Christopher H.

doi:10.1116/1.579965

Cited by 8 publications

(7 citation statements)

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“…Higher postionization irradiance can be obtained by further reducing laser spot. However, mass discrimination of ablated atoms with different motion velocities and, therefore, low mass resolution by the space charge effect in such a small postionization volume cannot be neglected . The larger postionization area is adopted, the more alleviative elemental fractionation is acquired.…”

Section: Methodsmentioning

confidence: 99%

“…Signal-to-noise ratio (SNR) is calculated by the ratio between peak intensities and 3σ values. a LOD of 57 Fe is chosen to calculate LOD for Fe rather than 54 Fe in GBW 921b due to the saturation of 56 Fe signal and 27 Al 2 + interference peak.…”

Section: Improved Detection Sensitivity Of Elements In Standard Allmentioning

confidence: 99%

“…However, mass discrimination of ablated atoms with different motion velocities and, therefore, low mass resolution by the space charge effect in such a small postionization volume cannot be neglected. [54][55][56] The larger postionization area is adopted, the more alleviative elemental fractionation is acquired. Under comprehensive consideration, some tradeoff was made among sensitivity, spectral resolution, and potential fractionation.…”

Section: Introductionmentioning

confidence: 99%

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Improved detection sensitivity of elements in solids via laser postionization in laser desorption time‐of‐flight mass spectrometry

et al. 2018

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A newly constructed laser desorption (532 nm, 5 ns) and laser postionization (266 nm, 5 ns) time-of-flight mass spectrometer (LD-LPI-TOFMS) has been applied for improving the detection sensitivity of elements in solid samples. This method affords to acquire the information of the elemental impurities in solid standards as well as limit of detection (LOD) down to 10 g/g for some elements. Neutral atoms of solids are generated by low-irradiance laser desorption (< 10 W/cm ), followed by high-irradiance laser postionization (~ 10 W/cm ) of the desorbed atoms, facilitating to decouple the desorption and ionization processes in spatial and temporal domain. This non-interacting feature overcomes the discrimination between deteriorating spectral resolution at high irradiance (10 -10 W/cm ) and limited detectable elemental species and high LOD at low or medium irradiance (below 10 W/cm ). The utilization of originally "wasted" neutral atoms by laser postionization will help improve atom utilization and instrumental sensitivity. In this work, getting the utmost out of the consumed neutral atoms instead of an increment in sampling amounts is given attention with high priority for achieving high sensitivity and low LOD, which is especially useful on the occasions where very low sample consumption is desired.

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Section: Methodsmentioning

confidence: 99%

Section: Improved Detection Sensitivity Of Elements In Standard Allmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved detection sensitivity of elements in solids via laser postionization in laser desorption time‐of‐flight mass spectrometry

et al. 2018

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“…Furthermore, in a very small ionization volume, poor spectral resolution derived from the space charge effect can be inevitable. 40,41 There is a trade-off in implementing desirable sensitivity and reasonable spectral resolution. Thus, a focused spot size of ∼500 μm in diameter was utilized for "capturing" neutral atoms.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Microtrace Analysis of Rare Earth Element Residues in Femtogram Quantities by Laser Desorption and Laser Postionization Mass Spectrometry

Yin

Liu

et al. 2017

Anal. Chem.

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A newly developed laser desorption and laser postionization time-of-flight mass spectrometer (LD-LPI-TOFMS) for the direct microtrace determination of rare earth elements (REEs) in residues has been presented. Benefiting from spatially and temporally separated processes between desorption and ionization, LD-LPI-TOFMS plays a dual role in alleviating the barriers of deteriorating spectral resolution at high irradiance, serious matrix effects and elemental fractionation effects at low irradiance. Compared with the conventional laser desorption/ionization (LDI) method, this technique offers unambiguous full-elemental determination of 15 REEs with more uniform relative sensitivity coefficients (RSCs) ranging from 0.5 to 2.5 for all REEs investigated, satisfying the semiquantitative analysis criteria. More importantly, a highly sensitive analysis of REEs with very little consumption was achieved by getting the utmost out of desorbed neutral atoms instead of increasing the amount of the sample, resulting in outstanding relative and absolute limits of detection (LODs and ALODs) of ∼ng/mL and ∼femtogram. The results presented here indicate that LD-LPI-TOFMS offers great potential in microtrace determination for elements in solution samples with minor sample preparation.

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“…For quantitative surface and material analysis, Becker and He et al [19][20][21][22] have studied some gases (Ar, Kr, NO, Xe, N 2 , and O 2 ) and solid samples (SiO 2 , GaAs, SiC and C1154 alloy) using a high intensity (10 14 -10 15 Wcm À2 ) 35 ps laser at 532 nm with time-of-flight mass spectrometry. The results, with the relative sensitivity factors (RSFs) close to unity, showed that the saturation of the multiphoton ionisation and uniform ionisation yields were achieved even for species with different ionisation potentials.…”

mentioning

confidence: 99%

Uniform molecular analysis using femtosecond laser mass spectrometry

Fang

Ledingham

Graham

et al. 1999

Rapid Commun. Mass Spectrom.

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The potential of femtosecond laser time-of-flight mass spectrometry (FLMS) for uniform quantitative analysis of molecules has been investigated. Various samples of molecular gases and vapours have been studied, using ultra-fast ( approximately 50 fs) laser pulses with very high intensity (up to 1.6 x 10(16) Wcm(-2)) for non-resonant multiphoton ionisation/tunnel ionisation. Some of these molecules have high ionisation potentials, requiring up to ten photons for non-resonant ionisation. The relative sensitivity factors (RSF) have been determined as a function of the laser intensity and it has been demonstrated that for molecules with very different masses and ionisation potentials, uniform ionisation has been achieved at the highest laser intensities. Quantitative laser mass spectrometry of molecules is therefore a distinct possibility. Copyright 1999 John Wiley & Sons, Ltd.

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Quantitative surface composition analysis using very high intensity nonresonant multiphoton ionization

Cited by 8 publications

References 0 publications

Improved detection sensitivity of elements in solids via laser postionization in laser desorption time‐of‐flight mass spectrometry

Improved detection sensitivity of elements in solids via laser postionization in laser desorption time‐of‐flight mass spectrometry

Microtrace Analysis of Rare Earth Element Residues in Femtogram Quantities by Laser Desorption and Laser Postionization Mass Spectrometry

Uniform molecular analysis using femtosecond laser mass spectrometry

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