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Chapter 18

Singlet Spin Order Originating from Para-H2

Parahydrogen induced singlet spin order provides an excellent tool for many NMR/MRI applications in the natural sciences and medicine. The huge benefit of para-H2 for NMR experiments is two-fold: it represents a pure spin state that can be very efficiently used in hyperpolarization experiments, and its singlet spin order may make it long-lived because it is immune to many relaxation mechanisms. By the method of Parahydrogen Induced Polarization (PHIP), para-H2 can be introduced in certain molecules giving rise to hyperpolarized long-lived singlet spin states under favourable experimental conditions. In this chapter, the quantum mechanical properties of H2 are briefly introduced, the procedure for para-H2 enrichment is explained and the basic concept of para-H2 induced polarization (PHIP) is presented. The application of PHIP for the generation of hyperpolarized long-lived states in low and high magnetic fields is summarized. Because singlet spin states are NMR inactive, a special focus must be set on strategies for a controlled conversion of the singlet state into an NMR detectable triplet state. The advantages and disadvantages of several methods for accomplishing this goal are discussed.

Publication details

Print publication date
15 Apr 2020
Copyright year
2020
Print ISBN
978-1-78801-568-4
PDF eISBN
978-1-78801-997-2
ePub eISBN
978-1-78801-998-9

From the book series:
New Developments in NMR