Boosting SABRE-SHEATH hyperpolarization with Coherent Control of Spin Dynamics

Signal Amplification By Reversible Exchange (SABRE) is a parahydrogen based hyperpolarization modality that is particularly simple, low-cost, and fast or even continuous. A more recent variant, SABRE-SHEATH (SABRE in SHield Enables Alignment Transfer to Heteronuclei) enables targeting ¹⁵N and ¹³C nuclei in a wide range of substrates, where hyperpolarization lifetimes can be particularly long. However, both SABRE and SABRE-SHEATH are limited by the incoherent nature of the hyperpolarization transfer process. Here we describe a pulsed variant of SABRE-SHEATH that takes coherent control over the spin dynamics and more than doubles achievable hyperpolarization levels. In addition, the pulsed SABRE-SHEATH experiments provide a new way of probing the hyperpolarization transfer, shedding new light on the limiting factors of this emerging technology.