Method and system for determining molecular structure
AssigneeFEI Company
InventorsBart Buijsse, Abhay Kotecha
Life of this patent
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Abstract
Molecular structure may be determined based on structure factors solved from the diffraction pattern and the electron microscopy image of the sample. In particular, the amplitudes of the structure factors may be determined based on intensities of diffraction peaks in the multiple diffraction patterns. The phases of the structure factors may be determined based on electron microscopy images and the intensities of the diffraction peaks.
Claims18
A method for determining a molecular structure of a sample, comprising:
- acquiring multiple diffraction patterns of the sample while tilting the sample relative to an incident beam;
- determining an amplitude of a structure factor based on intensities of a diffraction peak in the multiple diffraction patterns;
- acquiring a first electron microscopy (EM) image of the sample;
- after acquiring the first EM image, acquiring a second EM image with a current density higher than a current density for acquiring the first EM image;
- determining a phase of the structure factor based on the first EM image, the second EM image and the intensities of the diffraction peak in the multiple diffraction patterns;
- and
- determining the molecular structure of the sample based on the amplitude of the structure factor and the phase of the structure factor.
A non-transitory computer-readable medium comprising instructions that, when executed, cause a processor to:
- acquire multiple diffraction patterns of a sample while titling the sample relative to an incident beam;
- determine amplitudes of structure factors based on intensities of each diffraction peak in the multiple diffraction patterns;
- acquire multiple electron microscopy (EM) images of the sample at multiple tilt angles;
- determine intensities of Friedel pairs of the structure factors based on the intensities of the diffraction peaks;
- determine phases of the structure factors based on the multiple EM images and the intensities of Friedel pairs of the structure factors;
- and
- determine a molecular structure of the sample based on the amplitudes of the structure factors and the phases of the structure factors.
A system for determining a molecular structure of a sample, comprising:
- an electron source for generating an electron beam;
- a sample holder for tilting the sample relative to the electron beam;
- a first detector for acquiring a diffraction pattern of the sample;
- a second detector for acquiring an electron microscopy (EM) image of the sample;
- a controller with computer readable instructions stored in a non-transitory medium, configured to:
- direct the electron beam towards a first location of the sample and acquire multiple electron diffraction patterns of the sample via the first detector while the sample is tilted relative to the electron beam via the sample holder;
- determine an amplitude of a structure factor based on intensities of a diffraction peak in the multiple diffraction patterns;
- direct the electron beam to a second location of the sample and acquire a low dose EM image of the sample via the second detector;
- determine a phase of the structure factor based on the low dose EM image and the intensities of the diffraction peak;
- and
- determine the molecular structure of the sample based on the amplitude of the structure factor and the phase of the structure factor.
Dependencies are inferred from the claim text.