Atomic vibrations control all thermally activated processes in materials, including diffusion, heat transport, phase transformations and surface chemistry. Recent developments in scanning transmission electron microscopy (STEM) have enabled nanoscale probing of vibrational modes using electron energy-loss spectroscopy (EELS)1,2. Although atomically resolved analysis is routine in STEM, vibrational spectroscopy employing oscillating dipoles yields signals originating from regions tens of nanometres in size, because the scattering angles are only a few microradians3. Recently, it has been shown that energy-filtered images recorded at high scattering angles display atomic resolution4. Here we show, using conventional on-axis EELS, that non-dipole, impact scattering vibrational signals are present, and exhibit atomic resolution. This on-axis signal shows variations in the spectral peak shape and intensity as the electron probe is scanned across an individual atomic column in a Si sample. Although atomic spatial resolution in coherent elastic scattering will complicate the quantitative interpretation of spectra from crystals, the change in peak shape provides compelling evidence that the vibrational EELS excitation process is highly localized. High spatial resolution is also demonstrated in SiO2, an amorphous polar material. Our approach represents an important technical advance that will provide new insights into the local thermal, elastic and kinetic properties of materials.
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The experimental linescans and simultaneously acquired ADF signals analysed in this work have been uploaded to the Figshare repository. The data can be found at https://doi.org/10.6084/m9.figshare.c.4621640. Files have been uploaded in the easily readable 32-bit.tif image format. The data represented in Figs. 1b, 2c,d, 3b,c and 4a,c are available as Supplementary information files.
All of the MATLAB codes used to analyse the data are uploaded to B.D.A.L.’s GitHub page (https://github.com/bdalevin) under the repository titled ‘Background-Modelling-EELS-MATLAB-Code’.
Krivanek, O. L. et al. Vibrational spectroscopy in the electron microscope. Nature 514, 209–212 (2014).
Miyata, T. et al. Measurement of vibrational spectrum of liquid using monochromated scanning transmission electron microscopy–electron energy loss spectroscopy. Microscopy 63, 377–382 (2014).
Rez, P. Is localized infrared spectroscopy now possible in the electron microscope? Microsc. Microanal. 20, 671–677 (2014).
Hage, F. S., Kepaptsoglou, D. M., Ramasse, Q. M. & Allen, L. J. Phonon spectroscopy at atomic resolution. Phys. Rev. Lett. 122, 016103 (2019).
Lagos, M. J., Trugler, A., Hohenester, U. & Batson, P. E. Mapping vibrational surface and bulk modes in a single nanocube. Nature 543, 529–532 (2017).
Govyadinov, A. A. et al. Probing low-energy hyperbolic polaritons in van der Waals crystals with an electron microscope. Nat. Commun. 8, 95 (2017).
Idrobo, J. C. et al. Temperature measurement by a nanoscale electron probe using energy gain and loss spectroscopy. Phys. Rev. Lett. 120, 09590 (2018).
Lagos, M. J. & Batson, P. E. Thermometry with subnanometer resolution in the electron microscope using the principle of detailed balancing. Nano Lett. 18, 4556–4563 (2018).
Hage, F. S. et al. Nanoscale momentum-resolved vibrational spectroscopy. Sci. Adv. 4, eaar7495 (2018).
Jokisaari, J. R. et al. Vibrational spectroscopy of water with high spatial resolution. Adv. Mater. 30, 1802702 (2018).
Rez, P. et al. Damage-free vibrational spectroscopy of biological materials in the electron microscope. Nat. Commun. 7, 10945 (2016).
Haiber, D. & Crozier, P. A. Nanoscale probing of local hydrogen heterogeneity in disordered carbon nitrides with vibrational EELS. ACS Nano 12, 5463–5472 (2018).
Crozier, P. A., Aoki, T. & Liu, Q. Detection of water and its derivatives on individual nanoparticles using vibrational electron energy-loss spectroscopy. Ultramicroscopy 169, 30–36 (2016).
Egerton, R. F. Prospects for vibrational-mode EELS with high spatial resolution. Microsc. Microanal. 20, 658–663 (2014).
Forbes, B. D. & Allen, L. J. Modeling energy-loss spectra due to phonon excitation. Phys. Rev. B 94, 014110 (2016).
Dwyer, C. Localization of high-energy electron scattering from atomic vibrations. Phys. Rev. B 89, 054103 (2014).
Rez, P. Does phonon scattering give high-resolution images? Ultramicroscopy 52, 260–266 (1993).
Hohenester, U., Trügler, A., Batson, P. E. & Lagos, M. J. Inelastic vibrational bulk and surface losses of swift electrons in ionic nanostructures. Phys. Rev. B 97, 165418 (2018).
Spence, J. C. H. High Resolution Electron Microscopy 3rd edn (Oxford Science Publications, 2003).
Cowley, J. M. Image contrast in a transmission scanning electron microscope. Appl. Phys. Lett. 15, 58–59 (1969).
Ibach, H. & Mills, D. L. Electron Energy Loss Spectroscopy and Surface Vibrations (Academic Press, 1982).
Crozier, P. A. Vibrational and valence aloof beam EELS: a potential tool for nondestructive characterization of nanoparticle surfaces. Ultramicroscopy 180, 104–114 (2017).
Venkatraman, K., Rez, P., March, K. & Crozier, P. A. The influence of surfaces and interfaces on high spatial resolution vibrational EELS from SiO2. Microscopy 67, i14–i23 (2018).
Dwyer, C. et al. Electron-beam mapping of vibrational modes with nanometer spatial resolution. Phys. Rev. Lett. 117, 256101 (2016).
Jain, A. et al. Commentary: The Materials Project: a materials genome approach to accelerating materials innovation. APL Mater. 1, 011002 (2013).
Ong, S. P. et al. Python Materials Genomics (pymatgen): a robust, open-source python library for materials analysis. Comput. Mater. Sci. 68, 314–319 (2013).
Dolling, G. Lattice Vibrations in Crystals with the Diamond Structure (Atomic Energy of Canada Ltd, 1962).
Ashcroft, N. W. & Mermin, N. D. Solid State Physics (W.B. Saunders Company, 1976).
Kulda, J., Strauch, D., Pavone, P. & Ishii, Y. Inelastic-neutron-scattering study of phonon eigenvectors and frequencies in Si. Phys. Rev. B 50, 13347 (1994).
Haworth, R., Mountjoy, G., Corno, M., Ugliengo, P. & Newport, R. J. Probing vibrational modes in silica glass using inelastic neutron scattering with mass contrast. Phys. Rev. B 81, 060301 (2010).
Cueva, P., Hovden, R., Mundy, J. A., Xin, H. L. & Muller, D. A. Data processing for atomic resolution electron energy loss spectroscopy. Microsc. Microanal. 18, 667–675 (2012).
Zhu, J. T., Crozier, P. A., Ercius, P. & Anderson, J. R. Derivation of optical properties of carbonaceous aerosols by monochromated electron energy-loss spectroscopy. Microsc. Microanal. 20, 748–759 (2014).
Hall, M., Veeraraghavan, V., Rubin, H. & Winchell, P. The approximation of symmetric X-ray peaks by Pearson type VII distributions. J. Appl. Crystallogr. 10, 66–68 (1977).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).
Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).
Togo, A. & Tanaka, I. First principles phonon calculations in materials science. Scr. Mater. 108, 1–5 (2015).
Amali, A. & Rez, P. Theory of lattice resolution in high-angle annular dark-field images. Microsc. Microanal. 3, 28–46 (1997).
Financial support for K.V., B.D.A.L., P.R. and P.A.C. was provided by the US National Science Foundation (grant no. CHE-1508667) and for B.D.A.L. and P.A.C. by the US Department of Energy (grant no. DE-SC0004954). We also acknowledge the use of (S)TEM at John M. Cowley Center for High Resolution Electron Microscopy in the Eyring Materials Center at Arizona State University. P.A.C. acknowledges stimulating discussions on atomic-resolution vibrational spectroscopy with L. Allen. We acknowledge assistance from A. Singh in the use of Phonopy.
The authors declare no competing interests.
Peer review information Nature Physics thanks Robert Klie and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Venkatraman, K., Levin, B.D.A., March, K. et al. Vibrational spectroscopy at atomic resolution with electron impact scattering. Nat. Phys. 15, 1237–1241 (2019). https://doi.org/10.1038/s41567-019-0675-5
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