Spin and spectral signatures of polaron pairs in pi-conjugated polymers
Spin and spectral signatures of polaron pairs in pi-conjugated polymers
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DOI：
10.1103/physrevb.56.4626
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发表时间：
1997-08-15
影响因子：
3.7
通讯作者：
Vardeny, ZV
中科院分区：
文献类型：
--
作者：
Lane, PA;Wei, X;Vardeny, ZV
利用光诱导吸收（PA）和光探测磁共振（ODMR）研究了多种共轭聚合物薄膜中极化子对的光激发。发光聚合物和非发光聚合物都已被研究。极化子之间的交换相互作用拓宽了它们的磁共振谱，使得可以通过ODMR明确地识别极化子对物种。已观察到各向同性和各向异性交换相互作用。各向同性交换相互作用拓宽了与极化子相关的自旋1/2共振，而各向异性交换相互作用产生全场和半场粉末图案。我们已经成功地模拟了所观察到的自旋1/2 ODMR谱，并估计了各向同性交换相互作用I的强度。在C-60掺杂的2，5-二辛氧基聚对苯乙炔和富cia的聚乙炔中观察到了各向异性交换相互作用。极化子和极化子对都具有两个吸收带。然而，极化子对的高能PA带相对于孤立极化子的PA带蓝移，并且极化子对的低能PA带相对较弱。我们还观察到了简并基态聚合物中的中性孤子对激发。
We have studied polaron pair photoexcitations in a variety of rr-conjugated polymer films by photoinduced absorption (PA) and optically detected magnetic resonance (ODMR). Both luminescent and nonluminescent polymers have been studied. An exchange interaction between polarons broadens their magnetic resonance spectrum, permitting the unambiguous identification of the polaron pair species by ODMR, Both isotropic and anisotropic exchange interactions have been observed. An isotropic exchange interaction broadens the spin-1/2 resonance associated with polarons, whereas an anisotropic exchange interaction gives rise to both full-field and half-field powder patterns. We have successfully modeled the observed spin-1/2 ODMR spectra and estimate the strength of the isotropic exchange interaction I. An anisotropic exchange interaction has been observed in C-60-doped 2,5-dioctyloxy poly(p-phenylene vinylene) and cia-rich polyacetylene. Both polarons and polaron pairs are characterized by two absorption bands. However, the high-energy PA band of polaron pairs is blueshifted with respect to that of isolated polarons and the low-energy PA band of polaron pairs is relatively weak. We have also observed neutral soliton pair excitations in polymers with degenerate ground states.