Two-Dimensional (2D) NMR Methods

8 Multiple Acquisition Strategies

Nathaniel J. Traaseth

Department of Chemistry, New York University, New York, NY, USA

8.1 Introduction

Methodology advancements in NMR spectroscopy are typically classified as those involving improvements in sensitivity or resolution. The focus of this chapter is the detection of two or more free induction decays (FIDs) during a single experiment, referred to as multiple acquisitions. These detection schemes improve sensitivity of data collection since multiple datasets can be collected within the same time relative to the conventional experiment. Implementation of data collection requires suitable pulse sequences for detecting additional datasets and may involve the usage of two or more receivers for detecting FIDs on different nuclei. Several strategies and experiments are currently available, and this chapter classifies the approaches and underscores advantages relative to conventional experiments that detect a single FID.

8.2 Types of Multiple Acquisition Experiments

Acquisition of multiple datasets in one pulse sequence can be accomplished using sequential or simultaneous detection schemes (Figure 8.1). In the simplest form, two or more datasets can be collected with a single receiver, which requires detecting signals on the same nucleus concurrently or at different periods in the experiment (Figure 8.1a). The former method is called the time-shared experiment [1–3] and utilizes a single acquisition statement in the pulse sequence, whereas ...