Non-Standard Sample Environments Martin A. Schroer SAXS group - - PowerPoint PPT Presentation
Non-Standard Sample Environments Martin A. Schroer SAXS group Non-standard sample environments options at P12 Disclaimer Might not work for all samples Might not make sense for all samples You will likely need more sample
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Disclaimer
however
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Robotic sample changer SEC-SAXS/MALS
Stopped Flow Microfluidics (e.g. for THz) Laser excitation
28/02/2020
detection system
User setups:
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Air gap
Higher X-ray absorption by air Higher background signal (air + windows + sample cell)
In vacuum:
In air
Try to reduce the air gap as much as possible! Use proper window material!
+ BSA + buffer + buffer + BSA + buffer + buffer
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Sample changer temperature range
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Temperature controlled capillary holder
damage)
A good choice for:
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Examples:
Têmp.-induced melting of lamellar structures
Phase transition
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ATP
Josts et al, Structure 28, 348 (2020).
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Continuous change of Rg
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Continuous change of Rg
Continuous change of Rg But NOT overlapping Radiation Damage
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Continuous change of Rg
Continuous change of Rg But NOT overlapping Radiation Damage
Pump – probe scheme
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Continuous change of Rg
Continuous change of Rg But NOT overlapping Radiation Damage
Pump – probe scheme
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No unneeded exposure of sample Example:
+ Allows to determine the kinetics/reaction
(fibre port to P12 hutch experiments)
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To fibre Direct
Energy per pulse [mJ]
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0.5 1 1.5 2
q[nm-1]
104 105 106
I(q) [arb. u.]
0 s 30 s 60 s 120 s
50 100 150
delay time [s]
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
volume fraction
Monomer Dimer
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Real space maps of SAXS patterns
sized structures (shape, size) and orientation
tissue,...
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Example: Mineral particle distribution within a swordfish sword
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THz radiation
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Fröhlich‘s prediction
moment (Fröhlich condensation) Such collective vibrations (normal modes) may lead to long-range conformational changes. Such changes can be probed by SAXS. THz excitation & SAXS probe
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Such a noval type of experiment needs
(80 x 120 µm2) & smaller now!
Setup I Setup II
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Combined THz-SAXS measurements demand dedicated sample environment
sample excitation
3D printed Polystyrene cell with mylar X-ray windows W = 0.2 mm <-> optimized for THz T = 2 mm <-> optimized for X-rays
(TH Lübeck)
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Low as PS apolar
No absorption lines
Access to proteins of different molecular weight
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X-ray THz Noval cell design:
Setup installed at P12
The same stop of the sample is illuminated
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