Time resolved studies of pentacene triplets by electron spin echo spectroscopy

Yu, Hsiang-Lin; Lin, Tien‐Sung; Weissman, S. I.; Sloop, David J.

doi:10.1063/1.446491

Cited by 31 publications

(25 citation statements)

References 12 publications

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“…The spin-lattice relaxation rate and decay rates of the triplet sub-levels back to the singlet ground state are at least an order of magnitude slower than the spin dephasing rate so can be neglected. 22 Thus, the system is expected to be within the strong coupling regime since the predicted ensemble spin-photon coupling is an order of Fig. 1 Pentacene:p-terphenyl/STO cQED system.…”

Section: Resultsmentioning

confidence: 99%

Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states

et al. 2017

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The strong coupling regime is essential for efficient transfer of excitations between states in different quantum systems on timescales shorter than their lifetimes. The coupling of single spins to microwave photons is very weak but can be enhanced by increasing the local density of states by reducing the magnetic mode volume of the cavity. In practice, it is difficult to achieve both small cavity mode volume and low cavity decay rate, so superconducting metals are often employed at cryogenic temperatures. For an ensembles of N spins, the spin-photon coupling can be enhanced by ffiffiffi ffi N p through collective spin excitations known as Dicke states. For sufficiently large N the collective spin-photon coupling can exceed both the spin decoherence and cavity decay rates, making the strong-coupling regime accessible. Here we demonstrate strong coupling and cavity quantum electrodynamics in a solid-state system at room-temperature. We generate an inverted spin-ensemble with N~1015 by photo-exciting pentacene molecules into spin-triplet states with spin dephasing time T Ã 2 $ 3 μs. When coupled to a 1.45 GHz TE 01δ mode supported by a high Purcell factor strontium titanate dielectric cavity (V m $ 0:25 cm 3 , Q~8,500), we observe Rabi oscillations in the microwave emission from collective Dicke states and a 1.8 MHz normal-mode splitting of the resultant collective spin-photon polariton. We also observe a cavity protection effect at the onset of the strong-coupling regime which decreases the polariton decay rate as the collective coupling increases. 1 and a key feature is the strong coupling regime, where excitations are coherently transferred between different quantum systems over timescales significantly shorter than their lifetimes. A striking example is the Dicke state,

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Section: Resultsmentioning

confidence: 99%

Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states

et al. 2017

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“…For the NV − centers, the ground state is the triplet state, while in the case of pentacene, the ground state is the singlet state (S = 0). The zero-field splitting (ZFS) parameters D and E are 2870 MHz and ∼0 MHz for the NV − center and ∼1350 MHz and ∼42 MHz for pentacene in the excited state, the latter of which may vary depending on the host molecule (Yu et al, 1984). The electronic structure for these systems are shown in Fig.…”

Section: Discussion Open Accessmentioning

confidence: 99%

“…6(b)(c), η PBA p was estimated to be 0.565. The average electron polarization P P e between the two triplet sublevels over the field-sweep time was estimated using the populations over the zero-field eigenstates of the triplet state of pentacene doped in benzoic acid, which is known to be P x : P y : P z = 0.44 : 0.34 : 0.22 (Yu et al, 1984). Assuming that the external magnetic field is nearly perpendicular to the Z axis of the principal axis system of the ZFS tensor for the relevant electron-spin packets, we calculated the populations over the triplet sublevels in the magnetic field, and obtained P P e = 0.105 and η P t = 2/(3 − P P e ) = 0.69.…”

Section: Discussion Open Accessmentioning

confidence: 99%

“…x, y and z axes represent the principal axes of the ZFS tensor. (c) Orientational dependence of the polarization of the electron spins in the photo-excited triplet state of pentacene doped in benzoic acid in 0.39 T calculated from the zero-field population(Yu et al, 1984). The upper and lower rows correspond to the EPR transitions between the mS = +1 and the mS = 0 states, and between the mS = 0 and the mS = −1 states, respectively.…”

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Room temperature hyperpolarization of polycrystalline samples with optically polarized triplet electrons: Pentacene or Nitrogen-Vacancy center in diamond?

Miyanishi¹,

Segawa²,

Takeda³

et al. 2020

Preprint

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Abstract. We demonstrate room-temperature 13C hyperpolarization by dynamic nuclear polarization (DNP) using optically polarized triplet electron spins in two polycrystalline systems: pentacene-doped [carboxyl-13C] benzoic acid and microdiamonds containing NV- centers. For both samples, the integrated solid effect (ISE) is used to polarize the 13C spin system in magnetic fields of 350–400 mT. In the benzoic acid sample, the 13C spin polarization is enhanced up to 0.12 % through direct electron-to-13C polarization transfer without performing dynamic 1H polarization followed by 1H-13C cross polarization. In addition, ISE has been successfully applied for the first time to polarize naturally abundant 13C spins in a microdiamond sample to 0.01 %. To characterize the buildup of the 13C polarization, we discuss the efficiencies of direct polarization transfer between the electron and 13C spins as well as that of 13C–13C spin diffusion, examining various parameters which are beneficial or detrimental for successful bulk dynamic 13C polarization.

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“…by the desired application of the triplet system, triplet decay and SLR might not be disentangled in the kinetic data. For such intermediate cases, an approximate solution has been developed analytically [ 22 ] or found numerically by Runge-Kutta methods [ 23 , 24 ]. In the current manuscript we show that the exact differential equation system can be solved numerically to yield triplet decay as well as SLR kinetic parameters describing the experimental kinetic data in intermediate temperature regimes.…”

Section: Introductionmentioning

confidence: 99%

Heavy-atom effect on optically excited triplet state kinetics

2017

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In several fields of research, like e.g. photosensitization, photovoltaics, organic electroluminescent devices, dynamic nuclear polarization, or pulsed dipolar electron paramagnetic resonance spectroscopy, triplet state kinetics play an important role. It is therefore desirable to tailor the kinetics of photoexcited triplet states, e.g. by exploiting the intramolecular heavy-atom effect, and to determine the respective kinetic parameters. In this work, we set out to systematically investigate the photoexcited triplet state kinetics of a series of haloanthracenes by time-resolved electron paramagnetic resonance spectroscopy in combination with synchronized laser excitation. For this purpose, a procedure to simulate time traces by solving the differential equation system governing the triplet kinetics numerically is developed. This way, spin lattice relaxation rates and zero-field triplet life times are obtained concurrently by a global fit to experimental data measured at three different cryogenic temperatures.

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Time resolved studies of pentacene triplets by electron spin echo spectroscopy

Cited by 31 publications

References 12 publications

Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states

Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states

Room temperature hyperpolarization of polycrystalline samples with optically polarized triplet electrons: Pentacene or Nitrogen-Vacancy center in diamond?

Heavy-atom effect on optically excited triplet state kinetics

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