DESCRIPTION

The full-field Transmission X-ray Microscopy beamline MISTRAL (E = 270eV – 1200eV) is devoted to cryo nano-tomography in the water window for biological applications. In addition, spectroscopic imaging (a series of 2D images over a range of X-ray wavelengths) at several interesting X-ray absorption edges such as, for example, Ca, Ni, O & Fe can be performed, as well as magnetic imaging.

The Transmission X-ray Microscope (TXM) works from 270 eV to 1200 eV. A single-reflection elliptical glass capillary condenser focuses monochromatic light on to the sample, which is at cryo-temperature. The transmitted signal is collected by an objective Fresnel Zone plate (of 25 or 40 nm outermost zone widths) and a magnified image is delivered to a direct illumination CCD camera. The routinely expected spatial resolution in 2D is 30 nm and ~50 nm for tomographies. An epifluorescence visible light microscope on-line with the TXM allows for correlative microscopy.

Facilities for cryo sample preparation and cryo-screening of samples after vitrification are available for the users, as well as dedicated software for data analysis

IM-MISTRAL_Endstation  IM-MISTRAL_Endstation2


STATUS

The beamline went into operation for users on February 12th 2013. 

 

TECHNICAL SPECIFICATIONS 

Source Bending magnet
Energy range 270-1200 eV
Energy resolution up to E/DE = 5*103
Zone plates available 25 nm and 40 nm
Sample support
TEM round grid (3.05 mm), FEI autogrid sample holder available for dual-axis tomography
CryoTomography YES
Visible Light Fluorescence Fluorescence microscope on line; excitation filters: 450-490 nm & 510-560 nm
Tilt range ± 70º (40nm ZP) & ± 65º (25nm ZP)
Detector PIXIS-XO: 1024 * 1024, pixel size = 13 µm
Raw data format file format: XRM, raw data, HDF5, TIFF
file size per image: ~ 4 MB
Data analysis software ImageJ, IMOD, TOMO3D, TOMOJ, XMIPP
Preparation lab

Bio-lab (safety level 2). Plunge freezing preparation available.
Sample screening at cryo temperatures in transmitted, reflected light and fluorescence.

 

LAYOUT

Polychromatic radiation is delivered by a bending magnet. A VLS Plane Grating Monochromator (PGM) fills an elliptical glass capillary with light, which, in turn, focuses the light on to the sample. The transmitted signal is collected by an objective Fresnel Zone Plate and a magnified image is delivered to an X-ray CCD.

The following sketch shows the optical layout of the optics. A Kirkpatrick-Baez system focus light vertically (VFM) on to the entrance slit (Sin) and horizontally (HFM) on to the exit slit (Sout) of the vertically dispersive PGM. The monochromator works in standard imaging conditions with a constant slit-to-slit magnification in the dispersive plane of 1/cff = 1/2.25. It is constituted by a plane mirror PM and two varied line spacing gratings (VLS G), covering the whole energy range. An elliptical cylinder mirror (VRFM) will refocus the beam vertically onto the exit slit. The source is de-magnified horizontally by a factor of 3, and vertically by a factor of 3*2.25 times at the exit slit position.

The beamline layout including the Transmission X-ray Microscope is shown below:

MISTRAL LayoutMISTRAL Layout