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A New Mechanism of Raman Enhancement and its Application

机译：拉曼增强的新机制及其应用

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Strong electronic Raman bands corresponding to the transition between ~4I_(9/2) and ~4I_(11/2) manifolds of Ndo~(3+), caused by a Raman-enhancement effect, are observed in the FT-Raman spectrum of Nd_2O_3. neither resonance enhancement (RR) nor surface enhancement (SERS) accounts for the Raman enhancement observed here. We propose a new mechanism of Raman enhancement called the "feed-back" mechanism. A YAG laser excites the final state of the Raman transition (~4I_(11/2) of Nd~(3+)) to the ~4F_(3/2) state and causes a significant decrease in the population of Nd~(3+) at the ~4I_(11/2) state. This causes the population ratio of Nd~(3+) at ~4I_(9/2) and ~4I_(11/2) to deviate from the value required by Boltzmann's law. To restore equilibrium, Raman scattering is enhanced so that more Nd~(3+) ions are brought from the ~4I_(9/2) state to the ~4I_(11/2) state. This hypothesis gets support from the temperature-variable FT-Raman spectroscopic results. Additionally, obvious differences between the Stokes and anti-Stokes Raman spectrum of Nd~(3+) provide further evidence to support the feed-back mechanism. The Raman-enhancement effect confers on the electronic Raman bands a special ability to reflect the variation of coordinated structure around metal ions. The structural variations in polymer-metal ion composites and biomineralization systems have been investigated by using the electronic Raman bands.
机译：在拉曼光谱的FT-拉曼光谱中观察到强电子拉曼能带，对应于Ndo〜（3+）的〜4I_（9/2）和〜4I_（11/2）流形之间的过渡。 Nd_2O_3。共振增强（RR）和表面增强（SERS）都不能解释此处观察到的拉曼增强。我们提出了一种拉曼增强的新机制，称为“反馈”机制。 YAG激光激发拉曼跃迁的最终状态（Nd〜（3+）的〜4I_（11/2））到〜4F_（3/2）状态，并导致Nd〜（3 +）处于〜4I_（11/2）状态。这导致〜4I_（9/2）和〜4I_（11/2）处Nd〜（3+）的人口比偏离了玻耳兹曼定律要求的值。为了恢复平衡，增强了拉曼散射，以使更多的Nd〜（3+）离子从〜4I_（9/2）状态变为〜4I_（11/2）状态。该假设得到了温度可变的FT拉曼光谱结果的支持。另外，Nd〜（3+）的斯托克斯和反斯托克斯拉曼光谱之间的明显差异为支持反馈机制提供了进一步的证据。拉曼增强效应使电子拉曼带具有一种特殊能力，可以反映金属离子周围配位结构的变化。聚合物-金属离子复合材料和生物矿化系统的结构变化已通过使用电子拉曼谱带进行了研究。

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