TY - JOUR
T1 - Unraveling the Room-Temperature Spin Dynamics of Photoexcited Pentacene in Its Lowest Triplet State at Zero Field
AU - Wu, Hao
AU - Ng, Wern
AU - Mirkhanov, Shamil
AU - Amirzhan, Arman
AU - Nitnara, Supamas
AU - Oxborrow, Mark
N1 - Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/10/3
Y1 - 2019/10/3
N2 - Photoexcited pentacene, upon arriving via intersystem crossing into its lowest triplet state, has been extensively studied due to the large and relatively long-lived spin polarization that it exhibits. However, the spin dynamics of these triplets has not hitherto been accurately determined, with glaring inconsistencies between published values. Using zero-field transient electron paramagnetic resonance (ZF-trEPR), we here report the determination of a complete set of depopulation and spin-lattice relaxation rates for the lowest triplet state of pentacene doped at 0.1% into a p-terphenyl host crystal at room temperature in zero applied magnetic field. The rates of spin-lattice relaxation between the triplet's sublevels are found to be highly anisotropic (i.e., transition-specific) and not negligible compared to the rates of depopulation from the same three sublevels back to pentacene's ground state. The spin dynamics, as well as the ZF-trEPR technique reported here, can aid the rational, quantitative engineering of applications such as room-temperature masers and triplet dynamic nuclear polarization.
AB - Photoexcited pentacene, upon arriving via intersystem crossing into its lowest triplet state, has been extensively studied due to the large and relatively long-lived spin polarization that it exhibits. However, the spin dynamics of these triplets has not hitherto been accurately determined, with glaring inconsistencies between published values. Using zero-field transient electron paramagnetic resonance (ZF-trEPR), we here report the determination of a complete set of depopulation and spin-lattice relaxation rates for the lowest triplet state of pentacene doped at 0.1% into a p-terphenyl host crystal at room temperature in zero applied magnetic field. The rates of spin-lattice relaxation between the triplet's sublevels are found to be highly anisotropic (i.e., transition-specific) and not negligible compared to the rates of depopulation from the same three sublevels back to pentacene's ground state. The spin dynamics, as well as the ZF-trEPR technique reported here, can aid the rational, quantitative engineering of applications such as room-temperature masers and triplet dynamic nuclear polarization.
UR - http://www.scopus.com/inward/record.url?scp=85073106255&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.9b08439
DO - 10.1021/acs.jpcc.9b08439
M3 - Article
AN - SCOPUS:85073106255
SN - 1932-7447
VL - 123
SP - 24275
EP - 24279
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 39
ER -