Ilya Kuznetsov

Three-dimensional nanoscale molecular imaging by extreme ultraviolet laser ablation mass spectrometry

Analytical probes capable of mapping molecular composition at the nanoscale are of critical importance to materials research, biology and medicine. Mass spectral imaging makes it possible to visualize the spatial organization of multiple molecular components at a samples surface. However, it is challenging for mass spectral imaging to map molecular composition in three dimensions (3D) with submicron resolution. Here we describe a mass spectral imaging method that exploits the high 3D localization of absorbed extreme ultraviolet laser light and its fundamentally distinct interaction with matter to determine molecular composition from a volume as small as 50 zl in a single laser shot. Molecular imaging with a lateral resolution of 75 nm and a depth resolution of 20 nm is demonstrated. These results open opportunities to visualize chemical composition and chemical changes in 3D at the nanoscale.

Ablation and transmission of thin solid targets irradiated by intense extreme ultraviolet laser radiation

The interaction of an extreme ultraviolet (EUV) laser beam with a parylene foil was studied by experiments and simulation. A single EUV laser pulse of nanosecond duration focused to an intensity of 3 × 1010 W cm−2 perforated micrometer thick targets. The same laser pulse was simultaneously used to diagnose the interaction by a transmission measurement. A combination of 2-dimensional radiation-hydrodynamic and diffraction calculations was used to model the ablation, leading to good agreement with experiment. This theoretical approach allows predictive modelling of the interaction with matter of intense EUV beams over a broad range of parameters.

Characterization of extreme ultraviolet laser ablation mass spectrometry for actinide trace analysis and nanoscale isotopic imaging

We demonstrate a new technique for trace analysis that has nanometer scale resolution imaging capability: Extreme Ultraviolet Time-of-Flight Laser Ablation Mass Spectrometry (EUV TOF). We describe the characterization of this technique and discuss its advantages. Using the well-standardized NIST 61x glasses, the results show the EUV TOF spectra contain well defined signatures of U, Th, and their oxides, with far fewer spectral interferences than observed in Time-of-Flight Secondary Ion Mass Spectrometry (SIMS TOF). We demonstrate that the ratio of U and Th ions to the oxide ion signatures is adjustable with EUV laser pulse energy. Sample utilization efficiency (SUE) which measures the ratio of detected ions to atoms in the ablated volume was used as a measure of trace analysis sensitivity of EUV TOF. For U and Th, SUE is 0.014% and 0.017%, respectively, which is comparable to SIMS TOF in the same mass range. In imaging mode EUV TOF is capable to map variations in composition with a lateral resolution of 80 nm. Such high lateral resolution enabled mapping of the isotope distribution of 238U and 235U in closely spaced micron-size uranium oxide particles from isotope standard materials. Trace elemental sensitivity and nanometer spatial resolution gives EUV TOF great potential to dramatically improve the state-of-the-art laser ablation/ionization mass spectrometry and elemental spectro-microscopy for applications such as geochemical, forensic and environmental analysis.

Nanoscale 3D composition imaging by soft x-ray laser ablation mass spectrometry

We demonstrate a novel mass spectrometry nanoprobe that uses soft x-ray laser ablation to map chemical composition. Composition maps of metal/dielectric/polymer samples with 250nm surface and 50nm depth resolution were obtained.

Soft x-ray ablation mass spectrometry: high sensitivity elemental trace analysis

We have previously shown soft x-ray laser ablation time-of-flight mass spectrometry has the ability to detect singly ionized alanine molecules arising from the single shot ablation of a ∼50 zeptoliter volume. This superior sensitivity results from the ability to focus the 46.9 nm wavelength (26.4 eV energy per photon) laser beam to the diffraction limit, the strong absorption, and the efficient photoionization of the soft x-ray photons. In this paper we describe results on the application of soft x-ray laser mass spectrometry to elemental trace analysis in inorganic materials. Two dimensional imaging with spatial resolution of 80 nm in inorganic samples is also demonstrated.

Volumetric Composition Imaging at the Nanoscale by Soft X-Ray Laser Ablation Mass Spectrometry

Single shot soft x-ray laser ablation in combination with mass spectrometry is shown to make it possible to detect intact molecular ions from organic and inorganic materials from atto-liter volumes with high sensitivity. The technique is demonstrated to record 3D composition images of heterogeneous samples.

Soft X-Ray Laser Ablation Mass Spectrometry for Chemical Composition Imaging in Three Dimensions (3D) at the Nanoscale

Analytical probes capable of assessing the molecular composition and mapping it in 3D at the nanoscale will transform materials research, biology, and medicine. Herein, we describe recent advances of soft X-ray laser ablation mass spectral imaging that highlight the unique capabilities of the method to identify intact molecular content in dielectrics and fullerenes and to map the molecular composition of single microorganisms in 3D at the nanoscale.

Soft x-ray laser ablation mass spectrometry for materials study and nanoscale chemical imaging

There are significant advantages for using a compact capillary discharge soft x-ray laser (SXRL) with wavelength of 46.9 nm for mass spectrometry applications. The 26.4 eV energy photons provide efficient single-photon ionization while preserving the structure of molecules and clusters. The tens of nanometers absorption depth of the radiation coupled with the focusing of the laser beam to diameter of ∼100 nm result in the ablation of atto-liter scale craters which in turn enable high resolution mass spectral imaging of solid samples. In this paper we describe results on the analysis of composition depth-profiling of multilayer oxide stack and material studies in photoresists, ionic crystals, and magnesium corrosion products using SXRL ablation mass spectrometry, a method first demonstrated by our group. These materials are used in a variety of soft x-ray applications such as detectors, multilayer optics, and many more.