Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Natural abundance 13C NMR spectra of sample I, defined in the text. (a) Direct polarization (DP) and (b) 1H → 13C cross polarization (CP). The contact time for 1H → 13C CP was 1.4 ms. The data shown were accumulated with 14512 scans, with a recycle delay of 5s. All spectra are referenced to adamantane.
