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Research Highlight

Electrifying Neutrons: Identifying Isotopes in the Electron Microscope with Nanoscale Spatial Resolution

Identifying Single Isotopes
(Top) L-Alanine (L-Ala) enriched with 13C at carboxylate site exhibits significant shift in C-O stretching mode frequency. (Middle) Electron energy loss (EEL) spectra acquired between 12C and 13C nanoclusters. (Bottom) C-O peak positions used to distinguish between 12C and 13C L-Ala.

Scientific Achievement

First use of the electron microscope to identify site-specific isotopic labels with nanoscale resolution.

Significance and Impact

Method opens a pathway towards real-space tracking of labeled proteins in whole cell samples and direct observation of dynamic chemistry.

Research Details

– Vibrations between atoms in amino acids are measured without damaging the sample using state-of-the-art electron microscopy and spectroscopy.

– The results are validated and vibrational modes assigned with accurate 1st principles calculations.

– The technique identifies isotopes at individual atomic sites in amino acids on the same sample regions separated by nm-scale distances.

J.A. Hachtel, J. Huang, I. Popovs, S. Jansone-Popova, J.K. Keum, J. Jakowski, T.C. Lovejoy, N. Dellby, O.L. Krivanek, and J.C. Idrobo, “Identification of Site-Specific Isotopic Labels by Vibrational Spectroscopy in the Electron Microscope, ” Science, 363, 525 (2019).   DOI: 10.1126/science.aav5845