The Semi-selective 2D HMQC experiment is a simple modification of the 2D HMQC pulse sequence in which one of the two carbon 90 degree pulses is applied selectively on a specified region. The main purpose is to achieve better resolution in the indirect dimension and therefore is recommended when high overlapped carbon spectra precludes an easy resonance assignment. This same approach can be applied in the Semi-selective 2D HSQC experiment.

Easy implementation on any AVANCE spectrometer equipped with an inverse probehead.

A basic sequence was reported in 94JMRA100-111 . A gradient-enhanced version has also been published ( 94JMRA248-108 )

In order to achieve improved resolution, the user can also use digital filtering in the acquired proton dimension and apply linear prediction when data processing.

The semi-selective 2D HMQC experiment can be recorded in routine/automation modes. The most important parameter to optimize is the semi-selective carbon pulse length which determines the carbon spectral width to be excited.

Tutorials: 2D inverse experiments

Tutorials: 2D gradient-based inverse experiments

The spectrum offers the same correlation map as the conventional HMQC experiment.

Related experiments:

2D Inverse experiments

2D Inverse gradient-enhanced experiments