J. Maul

Direct Evidence for Condensation in the Early Solar System and Implications for Nebular Cooling Rates

We have identified in an acid resistant residue of the carbonaceous chondrite Murchison a large number (458) of highly refractory metal nuggets (RMNs) that once were most likely hosted by Ca,Al-rich inclusions (CAIs). While osmium isotopic ratios of two randomly selected particles rule out a presolar origin, the bulk chemistry of 88 particles with sizes in the submicron range determined by energy dispersive X-ray (EDX) spectroscopy shows striking agreement with predictions of single-phase equilibrium condensation calculations. Both chemical composition and morphology strongly favor a condensation origin. Particularly important is the presence of structurally incompatible elements in particles with a single-crystal structure, which also suggests the absence of secondary alteration. The metal particles represent the most pristine early solar system material found so far and allow estimation of the cooling rate of the gaseous environment from which the first solids formed by condensation. The resulting value of 0.5 K yr–1 is at least 4 orders of magnitude lower than the cooling rate of molten CAIs. It is thus possible, for the first time, to see through the complex structure of most CAIs and infer the thermal history of the gaseous reservoir from which their components formed by condensation.

Quantum confinement observed in the x-ray absorption spectrum of size distributed meteoritic nanodiamonds

We present a near edge x-ray absorption fine structure study of artificial chemical vapor deposition diamonds with sizes in the micron range and of size distributed nanodiamonds extracted from the Murchison meteorite. The modified peak shape in the case of the nanodiamond sample is explained by the interplay between the size distribution of the nanodiamonds and quantum confinement effects within a quantitative analysis based on the effective mass approximation theory.

Optical magnetic circular dichroism in threshold photoemission from a magnetite thin film

Threshold photoemission excited by polarization-modulated ultraviolet femtosecond laser light is exploited for phase-sensitive detection of magnetic circular dichroism (MCD) for a magnetite thin film. Magnetite (Fe(3)O(4)) shows a magnetic circular dichroism of ∼(4.5 ± 0.3) × 10(-3) for perpendicularly incident circularly polarized light and a magnetization vector switched parallel and antiparallel to the helicity vector by an external magnetic field. The asymmetry in threshold photoemission is discussed in comparison to the magneto-optical Kerr effect. The optical MCD contrast in threshold photoemission will provide a basis for future laboratory photoemission studies on magnetic surfaces.

At-wavelength inspection of sub-40 nm defects in extreme ultraviolet lithography mask blank by photoemission electron microscopy

A new at-wavelength inspection technology to probe nanoscale defects buried underneath Mo/Si multilayers on an extreme ultraviolet (EUV) lithography mask blank has been implemented using EUV photoemission electron microscopy (EUV-PEEM). EUV-PEEM images of programmed defect structures of various lateral and vertical sizes recorded at an ~13.5 nm wavelength show that 35 nm wide and 4 nm high buried line defects are clearly detectable. The imaging technique proves to be sensitive to small phase jumps, enhancing the edge visibility of the phase defects, which is explained in terms of a standing wave enhanced image contrast at resonant EUV illumination.

Transmission photoemission electron microscopy for lateral mapping of the X-ray absorption structure of a metalloprotein in a liquid cell

We use photoemission electron microscopy in an X-ray transmission mode for full-field imaging of the X-ray absorption structure of copper in the respiratory metalloprotein hemocyanin KLH1. It contains 160 oxygen binding sites. Each site reversibly binds one molecule oxygen between two copper atoms. In our setup, hemocyanin is dissolved in aqueous solution and enclosed in an ultra-high vacuum compatible liquid sample cell with silicon nitride membranes. The local X-ray absorption structure of the liquid sample is converted into photoelectrons at the microscope side of the cell acting as a photocathode. In this way, different copper valencies are laterally distinguished under in vivo-like conditions, attributed to Cu(I) in the deoxy-state and Cu(II) in the oxy-state.

Measurement of nanoparticle mass distributions by laser desorption/ionization time-of-flight mass spectrometry

In this paper, access to the mass distribution analysis of nanoparticles is described based on laser desorption/ionization and time of flight mass spectrometry. Two examples are given, demonstrating the accurate mass distribution analysis of nanoparticles fabricated both ex situ and in situ during the laser-assisted desorption process. The potentials and the limitations of the method are discussed, with special emphasis on carbonaceous clusters and molecules.

Actinic inspection of sub-50 nm EUV mask blank defects

A new actinic mask inspection technology to probe nano-scaled defects buried underneath a Mo/Si multilayer reflection coating of an Extreme Ultraviolet Lithography mask blank has been implemented using EUV Photoemission Electron Microscopy (EUV-PEEM). EUV PEEM images of programmed defect structures of various lateral and vertical sizes recorded at around 13 nm wavelength show that 35 nm wide and 4 nm high buried line defects are clearly detectable. The imaging technique proves to be sensitive to small phase jumps enhancing the visibility of the edges of the phase defects which is explained in terms of a standing wave enhanced image contrast at resonant EUV illumination.