Tobias Beetz

High-resolution ab initio Three-dimensional X-ray Diffraction Microscopy

Coherent x-ray diffraction microscopy is a method of imaging nonperiodic isolated objects at resolutions limited, in principle, by only the wavelength and largest scattering angles recorded. We demonstrate x-ray diffraction imaging with high resolution in all three dimensions, as determined by a quantitative analysis of the reconstructed volume images. These images are retrieved from the three-dimensional diffraction data using no a priori knowledge about the shape or composition of the object, which has never before been demonstrated on a nonperiodic object. We also construct two-dimensional images of thick objects with greatly increased depth of focus (without loss of transverse spatial resolution). These methods can be used to image biological and materials science samples at high resolution with x-ray undulator radiation and establishes the techniques to be used in atomic-resolution ultrafast imaging at x-ray free-electron laser sources.

Biological imaging by soft x-ray diffraction microscopy

We have used the method of x-ray diffraction microscopy to image the complex-valued exit wave of an intact and unstained yeast cell. The images of the freeze-dried cell, obtained by using 750-eV x-rays from different angular orientations, portray several of the cells major internal components to 30-nm resolution. The good agreement among the independently recovered structures demonstrates the accuracy of the imaging technique. To obtain the best possible reconstructions, we have implemented procedures for handling noisy and incomplete diffraction data, and we propose a method for determining the reconstructed resolution. This work represents a previously uncharacterized application of x-ray diffraction microscopy to a specimen of this complexity and provides confidence in the feasibility of the ultimate goal of imaging biological specimens at 10-nm resolution in three dimensions.

Soft X-ray radiation-damage studies in PMMA using a cryo-STXM

Radiation damage sets a fundamental limit for studies with ionizing radiation; cryo-methods are known to ease these limits. Here, measurements on mass loss and the decrease in the C=O bond density as measured by oxygen-edge XANES (NEXAFS) spectroscopy in thin films of poly(methylmethacrylate) (PMMA), studied in a vacuum, are reported. While cryo-methods allow more than 95% of the mass to remain at doses up to 10(7) Gy, there is little difference in C=O bond density versus dose between 298 K and 113 K sample temperatures. At both temperatures the critical dose for bond breaking is approximately 15 x 10(6) Gy.

Polaron melting and ordering as key mechanisms for colossal resistance effects in manganites.

Polarons, the combined motion of electrons in a cloth of their lattice distortions, are a key transport feature in doped manganites. To develop a profound understanding of the colossal resistance effects induced by external fields, the study of polaron correlations and the resulting collective polaron behavior, i.e., polaron ordering and transition from polaronic transport to metallic transport is essential. We show that static long-range ordering of Jahn–Teller polarons forms a polaron solid which represents a new type of charge and orbital ordered state. The related noncentrosymmetric lattice distortions establish a connection between colossal resistance effects and multiferroic properties, i.e., the coexistence of ferroelectric and antiferromagnetic ordering. Colossal resistance effects due to an electrically induced polaron solid–liquid transition are directly observed in a transmission electron microscope with local electric stimulus applied in situ using a piezo-controlled tip. Our results shed light onto the colossal resistance effects in magnetic field and have a strong impact on the development of correlated electron-device applications such as resistive random access memory (RRAM).

Instrumentation advances and detector development with the Stony Brook scanning transmission X-ray microscope

Driven by the requirements of new x-ray microscopy instrumentation the Stony Brook microscopy beamline X-1A has undergone considerable evolution [1]. The room temperature scanning transmission X-ray microscope (STXM) has been completely redesigned improving performance, case of use and compatibility with other experiments. We present the highlights of the new design, the available detectors and the result of early tests of this new microscope.

An in-vacuum x-ray diffraction microscope for use in the 0.7–2.9 keV range

A dedicated in-vacuum coherent x-ray diffraction microscope was installed at the 2-ID-B beamline of the Advanced Photon Source for use with 0.7-2.9 keV x-rays. The instrument can accommodate three common implementations of diffractive imaging; plane wave illumination; defocused-probe (Fresnel diffractive imaging) and scanning (ptychography) using either a pinhole, focused or defocused probe. The microscope design includes active feedback to limit motion of the optics with respect to the sample. Upper bounds on the relative optics-to-sample displacement have been measured to be 5.8 nm(v) and 4.4 nm(h) rms/h using capacitance micrometry and 27 nm/h using x-ray point projection imaging. The stability of the measurement platform and in-vacuum operation allows for long exposure times, high signal-to-noise and large dynamic range two-dimensional intensity measurements to be acquired. Finally, we illustrate the microscopes stability with a recent experimental result.

Scanning transmission soft x-ray microscopy at beamline X-1A at the NSLS: advances in instrumentation and selected applications

Soft x-ray scanning transmission x-ray microscopy allows one to image dry and wet environmental science, biological, polymer, and geochemical specimens on a nanoscale. Recent advances in instrumentation at the X-1A beamline at the National Synchrotron Light Source at Brookhaven National Laboratory are described. Recent results on Nomarski differential phase contrast and first results on investigations at the oxygen K edge and iron L edge of hydrous ferric oxide transformations are presented.

SPECTROMICROSCOPY OF BIOLOGICAL AND ENVIRONMENTAL SYSTEMS AT STONY BROOK: INSTRUMENTATION AND ANALYSIS

Soft X-ray microscopy allows one to study nanoscale heterogeneities in dry and wet environmental science, biological, polymer, and geochemical specimens. Recent advances in instrumentation at the X-1A beamline at the National Synchrotron Light Source at Brookhaven National Laboratory are described. Spectromicroscopy data analysis methods including component mapping and principal component analysis (PCA) are then discussed.

SOFT X-RAY MICROSCOPY AT THE NSLS

TOBIAS BEETZ, MICHAEL FESER, HOLGER FLECKENSTEIN, BENJAMIN HORNBERGER, CHRIS JACOBSEN, JANOS KIRZ, MIRNA LEROTIC, ENJU LIMA, MING LU, 1 DAVID SAYRE, DAVID SHAPIRO, AARON STEIN, D O N TENNANT, AND SUE WIRICK 1 Department of Physics & Astronomy, Stony Brook University, Stony Brook NY 11794, USA 2 Brookhaven National Laboratory, Upton, NY 11973-5000, USA New Jersey Nanotechnology Consortium, 600-700 Mountain Ave, Murray Hill, NJ 07974, USA

Structure Determination of Isolated Single-Walled Carbon Nanotubes by Electron Diffraction and Diffraction Microscopy

Iijima discovered carbon nanotubes (CNTs) in 1991 as a by-product of the preparation method to produce fullerenes [1]. The exceptional mechanical, electrical and chemical properties of CNTs offer significant advantages over many existing materials. The structure of a CNT determines its properties and therefore much work has been done on determining the exact structure. Here we report the unambigous structure determination of isolated single-walled CNTs that were previously studied using Rayleigh scattering to probe the electronic transitions [2]. Electron diffraction patterns of isolated single-walled CNTs were collected using a JEOL3000F electron microscope at a reduced operating voltage to minimize radiation damage. We used a parallel illumination with a diameter of about 60 nm as described by Gao et al. [3]. Diffraction patterns were recorded on Fuji image plates which offer a good dynamic range and no ‘blooming’ effect compared to CCD cameras. This acquisition technique results in very clear diffraction patterns as shown in FIG.1.b). To determine the chiral vector of the nanotube, the experimental diffraction patterns were fitted with simulated ones of nanotubes that have a diameter consistent within the diameter range determined at imaging conditions. FIG.1.c) shows the experimental diffraction pattern overlaid with the simulated diffraction pattern of a (27,11) tube, which is perfectly matched and the structure is also consistent when the method used by Gao et al. [3] is applied to the experimental data.