Abstract：
Cellulose nanofiber (CNFs) obtained through TEMPO oxidation was structurally characterized using FT-IR (Fourier Transformed Infrared) and SEM (Scanning Electron Microscopy) spectroscopy. The molecular aggregation and spectroscopic properties of Rhodamine B (Rh-B) in CNFs suspension were investigated using molecular absorption and steady-state fluorescence spectroscopy techniques. The interaction between CNFs particles in the aqueous suspension and the cationic dye compound was examined in comparison to its behavior in deionized water. This interaction led to significant changes in the spectral features of Rh-B, resulting in an increase in the presence of H-dimer and H-aggregate in CNFs suspension. The H-type aggregates of Rh-B in CNFs suspensions were defined by the observation of a blue-shifted absorption band compared to that of the monomer. Even at diluted dye concentrations, the formation of Rh-B\'s H-aggregate was observed in CNFs suspension. The pronounced aggregation in suspensions originated from the strong interaction between negatively charged carboxylate ions and the dye. The aggregation behavior was discussed with deconvoluted absorption spectra. Fluorescence spectroscopy studies revealed a significant reduction in the fluorescence intensity of the dye in CNFs suspension due to H-aggregates. Furthermore, the presence of H-aggregates in the suspensions caused a decrease in the quantum yield of Rh-B compared to that in deionized water.
摘要：
通过TEMPO氧化获得的纤维素纳米纤维（CNFs）使用FT-IR（傅立叶变换红外）和SEM（扫描电子显微镜）光谱进行结构表征。利用分子吸收和稳态荧光光谱技术研究了罗丹明B（Rh-B）在CNFs悬浮液中的分子聚集和光谱性质。与其在去离子水中的行为相比，检查了水性悬浮液中CNF颗粒与阳离子染料化合物之间的相互作用。这种相互作用导致Rh-B的光谱特征发生显著变化，导致CNFs悬浮液中H-二聚体和H-聚集体的存在增加。CNF悬浮液中Rh-B的H型聚集体通过与单体相比的蓝移吸收带的观察来定义。即使在稀释的染料浓度下，在CNFs悬浮液中观察到Rh-B的H-聚集体的形成。悬浮液中明显的聚集源于带负电荷的羧酸根离子与染料之间的强相互作用。用解卷积吸收光谱讨论了聚集行为。荧光光谱研究表明，由于H聚集体，CNF悬浮液中染料的荧光强度显着降低。此外，与去离子水相比，悬浮液中H聚集体的存在导致Rh-B的量子产率降低。
