Nanosecond time-resolved characterization of a pentacene-based room-temperature MASER.
Nanosecond time-resolved characterization of a pentacene-based room-temperature MASER.
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DOI：
10.1038/srep41836
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发表时间：
2017-02-07
影响因子：
4.6
通讯作者：
Kay CW
中科院分区：
文献类型：
--
作者：
Salvadori E;Breeze JD;Tan KJ;Sathian J;Richards B;Fung MW;Wolfowicz G;Oxborrow M;Alford NM;Kay CW
已对工作频率为 1.45GHz 的室温零场 MASER 的性能进行了检查。纳秒激光脉冲在自旋动力学的时间尺度上本质上是瞬时的，允许将可见光到微波的转换效率和 MASER 的时间响应作为激发能量的函数进行测量。据观察，MASER 输出脉冲的时序和幅度与激光激发能量相关：在较高的激光能量下，微波脉冲比在较低的激光能量下记录的微波脉冲具有更大的幅度并且在更短的延迟后出现。播种实验表明，输出变化可以通过外部源稳定并确定所需的最小播种功率。 MASER 发射的动力学可以通过一对一阶非线性微分方程来建模，该微分方程源自 Lotka-Volterra 模型（捕食者-猎物），其中谐振器的微波模式是捕食者，并五苯三重态的自旋极化是猎物。模拟可以估计受激发射的爱因斯坦系数、自旋晶格弛豫以及对 MASER 发射有贡献的三重态数量。这些是合理改进基于自旋极化三重态分子的 MASER 的重要参数。
The performance of a room temperature, zero-field MASER operating at 1.45 GHz has been examined. Nanosecond laser pulses, which are essentially instantaneous on the timescale of the spin dynamics, allow the visible-to-microwave conversion efficiency and temporal response of the MASER to be measured as a function of excitation energy. It is observed that the timing and amplitude of the MASER output pulse are correlated with the laser excitation energy: at higher laser energy, the microwave pulses have larger amplitude and appear after shorter delay than those recorded at lower laser energy. Seeding experiments demonstrate that the output variation may be stabilized by an external source and establish the minimum seeding power required. The dynamics of the MASER emission may be modeled by a pair of first order, non-linear differential equations, derived from the Lotka-Volterra model (Predator-Prey), where by the microwave mode of the resonator is the predator and the spin polarization in the triplet state of pentacene is the prey. Simulations allowed the Einstein coefficient of stimulated emission, the spin-lattice relaxation and the number of triplets contributing to the MASER emission to be estimated. These are essential parameters for the rational improvement of a MASER based on a spin-polarized triplet molecule.