Confocal Raman microscopy was used as a non‐destructive tool for in situ investigation of the diffusion of CI Reactive Blue 194 in viscose fibres. Dyed fibres were analysed by Raman depth imaging along the radius at different dyeing times (30, 60, 90, 120, 150, 180, 240, 300, 600, 900, 1200, 1500, 1800, 2100 and 2400 seconds) and temperatures (30, 40, 50, 60, 70 and 80°C). The dye concentration in the fibre was expressed by normalising the characteristic peak of dyes at 1577 cm⁻¹ to eliminate the interference of the fibre. The Raman depth mapping images showed that dye molecules gradually diffused to the interior of the fibre with an increase in dyeing time, remaining ring‐shaped in the state of diffusion. In addition, the diffusion rate increased with increases in the dyeing temperature. This was understandable because dye molecules with a higher kinetic energy move faster. It was also found that the external structure of fibres played a significant role in the diffusion behaviour of CI Reactive Blue 194 during the initial stage of dyeing. The concentration gradient distribution of CI Reactive Blue 194 in the fibre was reflected by Raman depth mapping. The study demonstrates the potential of confocal Raman microscopy for monitoring the dynamic diffusion of dye molecules in fibres.

中文翻译：

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共聚焦拉曼显微镜研究活性染料在纤维素纤维中的扩散行为

共焦拉曼显微镜被用作非破坏性工具，用于原位研究CI反应性蓝194在粘胶纤维中的扩散。通过拉曼深度成像在不同的染色时间（30、60、90、120、150、180、240、300、600、900、1200、1500、1800、2100和2400秒）和半径下沿半径分析染色的纤维30、40、50、60、70和80°C）。通过归一化染料在1577 cm ^-1处的特征峰来表达纤维中的染料浓度消除光纤的干扰。拉曼深度图显示，随着染色时间的增加，染料分子逐渐扩散到纤维内部，并在扩散状态下保持环形。另外，扩散速度随着染色温度的升高而增加。这是可以理解的，因为具有较高动能的染料分子移动得更快。还发现在染色的初始阶段，纤维的外部结构在CI活性蓝194的扩散行为中起重要作用。纤维中CI反应蓝194的浓度梯度分布通过拉曼深度图反映。该研究证明了共聚焦拉曼显微镜在监测纤维中染料分子动态扩散方面的潜力。