TY - JOUR

T1 - Magnetic field dependence of triplet-state ONP

T2 - theoretical analysis in terms of level anti-crossings

AU - Sosnovsky, Denis V.

AU - Ivanov, Konstantin L.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - A theoretical approach to Optical Nuclear Polarisation (ONP) is described, which is based on the analysis of Level Anti-Crossings (LACs) in triplet states. Here we consider ONP formed in molecular crystals doped with suitable guest molecules and ONP generated in diamond crystals containing negatively charged nitrogen-vacancy (NV–) centres. In both cases, electron spin polarisation of triplet states generated by light excitation is transferred to nuclei giving rise to ONP. Polarisation transfer is most efficient at LACs; for this reason, we consider in detail crossings of electron–nuclear energy levels and the role of different perturbation terms (coming from isotropic and anisotropic hyperfine coupling, zero-field splitting and sample orientation), which turn these crossings into LACs and give rise to ONP. Analytical results are supported by numerical calculations of the ONP field dependences. Thus, the outlined LAC analysis is a useful approach for interpreting the ONP magnetic field dependence.

AB - A theoretical approach to Optical Nuclear Polarisation (ONP) is described, which is based on the analysis of Level Anti-Crossings (LACs) in triplet states. Here we consider ONP formed in molecular crystals doped with suitable guest molecules and ONP generated in diamond crystals containing negatively charged nitrogen-vacancy (NV–) centres. In both cases, electron spin polarisation of triplet states generated by light excitation is transferred to nuclei giving rise to ONP. Polarisation transfer is most efficient at LACs; for this reason, we consider in detail crossings of electron–nuclear energy levels and the role of different perturbation terms (coming from isotropic and anisotropic hyperfine coupling, zero-field splitting and sample orientation), which turn these crossings into LACs and give rise to ONP. Analytical results are supported by numerical calculations of the ONP field dependences. Thus, the outlined LAC analysis is a useful approach for interpreting the ONP magnetic field dependence.

KW - molecular crystals

KW - NV-centres

KW - optical nuclear polarisation

KW - Spin hyperpolarisation

KW - triplet states

KW - MECHANISM

KW - OPTICAL NUCLEAR-POLARIZATION

KW - RELAXATION

KW - ANTHRACENE-TETRACYANOBENZENE

KW - SPIN POLARIZATION

KW - PROTONS

KW - ORIENTATION

KW - CONSEQUENCE

KW - CRYSTALS

KW - HYPERPOLARIZATION

UR - http://www.scopus.com/inward/record.url?scp=85051978467&partnerID=8YFLogxK

U2 - 10.1080/00268976.2018.1504996

DO - 10.1080/00268976.2018.1504996

M3 - Article

AN - SCOPUS:85051978467

VL - 117

SP - 2740

EP - 2755

JO - Molecular Physics

JF - Molecular Physics

SN - 0026-8976

IS - 19

ER -