The detailed chemical structure of graphite oxide (GO), a layered material prepared from graphite almost 150 years ago and a precursor to chemically modified graphenes, has not been previously resolved because of the pseudo-random chemical functionalization of each layer, as well as variations in exact composition. Carbon-13 ( ¹³ C) solid-state nuclear magnetic resonance (SSNMR) spectra of GO for natural abundance ¹³ C have poor signal-to-noise ratios. Approximately 100% ¹³ C-labeled graphite was made and converted to ¹³ C-labeled GO, and ¹³ C SSNMR was used to reveal details of the chemical bonding network, including the chemical groups and their connections. Carbon-13–labeled graphite can be used to prepare chemically modified graphenes for ¹³ C SSNMR analysis with enhanced sensitivity and for fundamental studies of ¹³ C-labeled graphite and graphene.

The authors report on time-resolved near-field spectroscopy of $\mathrm{Zn}\mathrm{O}∕\mathrm{Zn}\mathrm{Mg}\mathrm{O}$ nanorod double-quantum-well structures (DQWs) for a nanometer-scale photonic device. They observed nutation of the population between the resonantly coupled exciton states of DQWs. Furthermore, they demonstrated switching dynamics by controlling the exciton excitation in the dipole-inactive state via an optical near field. The results of time-resolved near-field spectroscopy of isolated DQWs described here are a promising step toward designing a nanometer-scale photonic switch and related devices.