The adsorption and orientations of 2-(trichloroacetyl)pyrrole (TCAP) adsorbed on a fabricated silver-coated thin film (SCF), and gold-coated thin film (GCF) were investigated using surface-enhanced Raman scattering (SERS) studies and compared with the normal Raman scattering (nRs) spectrum of TCAP. The observed nRs and SERS spectra of TCAP were validated theoretically using DFT quantum chemical calculations. Initially, the molecular structure of TCAP, TCAP-Ag₃, and TCAP-Au₄ molecular systems were optimized and analyzed. The fabricated SCF and GCF are characterized using FESEM analysis, which confirms that the silver and gold nanoparticles of the corresponding films are spherical in shape. The obtained significant red-shift in UV-visible spectra of TCAP added on SCF and GCF surfaces reveal that the TCAP strongly adsorbed on SCF and GCF surfaces. The frontier molecular orbitals analysis authenticates the charge-transfer interaction from Ag₃ and Au₄ metal clusters to the TCAP molecule, leading to the adsorption of TCAP molecule on Ag₃ and Au₄ metal clusters, which validates the UV-vis results. SERS spectral analysis confirms that the TCAP chemisorbed on SCF and GCF surfaces with tilted orientation and the corresponding results were validated theoretically. The calculated SERS enhancement factor values illustrate that the GCF surface exhibits a higher SERS signal enhancement than the SCF surface. Therefore, the present investigation will be useful for the development of active SERS substrates and pyrrole-related biosensors.

中文翻译：

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2-(三氯乙酰基)吡咯化学吸附在银和金涂层薄膜表面的 SERS 和 DFT 研究：从生物传感器应用的角度来看

使用表面增强拉曼散射 (SERS) 研究研究了 2-(三氯乙酰基) 吡咯 (TCAP) 吸附在制造的镀银薄膜 (SCF) 和镀金薄膜 (GCF) 上的吸附和取向，并进行了比较与 TCAP 的正常拉曼散射 (nRs) 光谱。使用 DFT 量子化学计算在理论上验证了观察到的 TCAP 的 nR 和 SERS 光谱。最初，TCAP、TCAP-Ag ₃和 TCAP-Au _{4的分子结构}分子系统进行了优化和分析。使用 FESEM 分析对制造的 SCF 和 GCF 进行了表征，这证实了相应薄膜的银和金纳米颗粒是球形的。在 SCF 和 GCF 表面上添加的 TCAP 的紫外可见光谱中获得的显着红移表明 TCAP 强烈吸附在 SCF 和 GCF 表面上。_{前沿分子轨道分析验证了从 Ag 3}和 Au ₄金属簇到 TCAP 分子的电荷转移相互作用，导致 TCAP 分子吸附在 Ag ₃和 Au _4上金属簇，它验证了紫外可见结果。SERS光谱分析证实TCAP化学吸附在倾斜方向的SCF和GCF表面上，相应的结果在理论上得到了验证。计算的 SERS 增强因子值说明 GCF 表面比 SCF 表面表现出更高的 SERS 信号增强。因此，本研究将有助于开发活性 SERS 底物和吡咯相关生物传感器。