Editing Dynamic nuclear polarization (section)

===DNP-NMR===
DNP can be performed to enhance NMR signals but also to introduce an inherent spatial dependence: the magnetization enhancement takes place in the vicinity of the irradiated electrons and propagates throughout the sample. Spatial selectivity can finally be obtained using [[magnetic resonance imaging]] (MRI) techniques, so that signals from similar parts can be separated based on their location in the sample.<ref>{{cite journal |last1=Moroz |first1=Ilia B. |last2=Leskes |first2=Michal |title=Dynamic Nuclear Polarization Solid-State NMR Spectroscopy for Materials Research |journal=Annual Review of Materials Research |date=1 July 2022 |volume=52 |issue=1 |pages=25–55 |doi=10.1146/annurev-matsci-081720-085634 |bibcode=2022AnRMS..52...25M |s2cid=247375660 |url=https://www.annualreviews.org/doi/abs/10.1146/annurev-matsci-081720-085634 |language=en |issn=1531-7331|doi-access=free }}</ref><ref name="sciencedirect.com">{{cite journal |last1=Bagheri |first1=Khashayar |last2=Deschamps |first2=Michael |last3=Salager |first3=Elodie |title=Nuclear magnetic resonance for interfaces in rechargeable batteries |journal=Current Opinion in Colloid & Interface Science |date=1 April 2023 |volume=64 |pages=101675 |doi=10.1016/j.cocis.2022.101675 |s2cid=255364390 |url=https://hal.science/hal-03925315/file/20221126_COCIS_revised.pdf |language=en |issn=1359-0294}}</ref>
DNP has triggered enthusiasm in the NMR community because it can enhance sensitivity in [[Solid-state nuclear magnetic resonance|solid-state NMR]]. In DNP, a large electronic [[spin polarization]] is transferred onto the nuclear spins of interest using a microwave source. There are two main DNP approaches for solids. If the material does not contain suitable unpaired electrons, exogenous DNP is applied: the material is impregnated by a solution containing a specific radical. When possible, endogenous DNP is performed using the electrons in [[transition metal]] ions (metal-ion dynamic nuclear polarization, MIDNP) or [[Valence and conduction bands|conduction electrons]]. The experiments usually need to be performed at low temperatures with [[magic angle spinning]]. It is important to note that DNP was only performed ex situ as it usually requires low temperature to lower electronic relaxation.<ref name="sciencedirect.com"/>