Related Experiment Video
Updated: Jan 30, 2026

Reconstitution of Nucleosomes with Differentially Isotope-labeled Sister Histones
Published on: March 26, 2017
Identification of site-specific isotopic labels by vibrational spectroscopy in the electron microscope
Jordan A Hachtel1, Jingsong Huang2,3, Ilja Popovs4
1Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. hachtelja@ornl.gov idrobojc@ornl.gov.
Abstract:
The identification of isotopic labels by conventional macroscopic techniques lacks spatial resolution and requires relatively large quantities of material for measurements. We recorded the vibrational spectra of an α amino acid, l-alanine, with damage-free "aloof" electron energy-loss spectroscopy in a scanning transmission electron microscope to directly resolve carbon-site-specific isotopic labels in real space with nanoscale spatial resolution. An isotopic red shift of 4.8 ± 0.4 milli-electron volts in C-O asymmetric stretching modes was observed for 13C-labeled l-alanine at the carboxylate carbon site, which was confirmed by macroscopic infrared spectroscopy and theoretical calculations. The accurate measurement of this shift opens the door to nondestructive, site-specific, spatially resolved identification of isotopically labeled molecules with the electron microscope.
Related Concept Videos
Isotopes
An element's atomic mass, or weight,...
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...
Elements: Chemical Symbols and Isotopes
Some symbols are derived from the common English name of the element; others are abbreviations of the name in another language — Latin, Greek or German. For example, the symbol for aluminum (common name)...
Electron Microscope Tomography and Single-particle Reconstruction
Electron Tomography
Electron tomography can be performed either in TEM or STEM (scanning transmission...
UV–Vis Spectroscopy: Molecular Electronic Transitions

