Mann Sarah K, Cowley-Semple Angus, Bryan Emma, Huang Ziqiu, Heutz Sandrine, Attwood Max, Bayliss Sam L
James Watt School of Engineering, University of Glasgow, Glasgow G12 8QQ, U.K.
Department of Materials and London Centre for Nanotechnology, Imperial College London, Prince Consort Road, London SW7 2AZ, U.K.
J Am Chem Soc. 2025 Jul 2;147(26):22911-22918. doi: 10.1021/jacs.5c05505. Epub 2025 Jun 17.
Optical detection of magnetic resonance enables spin-based quantum sensing with high spatial resolution and sensitivity─even at room temperature─as exemplified by solid-state defects. Molecular systems provide a complementary, chemically tunable, platform for room-temperature optically detected magnetic resonance (ODMR)-based quantum sensing. A critical parameter governing sensing sensitivity is the optical contrast─i.e., the difference in emission between two spin states. In state-of-the-art solid-state defects such as the nitrogen-vacancy center in diamond, this contrast is approximately 30%. Here, capitalizing on chemical tunability, we show that room-temperature ODMR contrasts of 40% can be achieved in molecules. Using a nitrogen-substituted analogue of pentacene (6,13-diazapentacene), we enhance contrast compared to pentacene and, by determining the triplet kinetics through time-dependent pulsed ODMR, show how this arises from accelerated anisotropic intersystem crossing. Furthermore, we translate high-contrast room-temperature pulsed ODMR to self-assembled nanocrystals. Overall, our findings highlight the synthetic handles available to optically readable molecular spins and the opportunities to capitalize on chemical tunability for room-temperature quantum sensing.
磁共振的光学检测能够实现基于自旋的量子传感，具有高空间分辨率和灵敏度，甚至在室温下也是如此，固态缺陷就是例证。分子系统为基于室温光学检测磁共振（ODMR）的量子传感提供了一个互补的、化学可调的平台。决定传感灵敏度的一个关键参数是光学对比度——即两种自旋态之间的发射差异。在诸如金刚石中的氮空位中心等先进固态缺陷中，这种对比度约为30%。在此，利用化学可调性，我们表明在分子中可以实现40%的室温ODMR对比度。使用并五苯的氮取代类似物（6,13-二氮杂并五苯）相比并五苯，我们提高了对比度，并通过随时间变化的脉冲ODMR确定三重态动力学，展示了这是如何由加速各向异性系间窜越产生 的。此外，我们将高对比度室温脉冲ODMR转化为自组装纳米晶体。总体而言我们研究结果突出了可用于光学可读分子自旋的合成手段，以及利用化学可调性实现室温量子传感 的机会。
