Baek Na Yeon, Kim Jangwon, Lee Ji Eun, Kim Jae Hoon
Department of Physics, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul 03722, Republic of Korea.
ACS Omega. 2023 Mar 31;8(14):12702-12706. doi: 10.1021/acsomega.2c07778. eCollection 2023 Apr 11.
Terahertz spectroscopy has been increasingly utilized as an effective nondestructive tool for the diagnosis, analysis, and restoration of artworks. In particular, in the case of artist's pigments, the terahertz probe reveals the vibrational modes that are unique to a given pigment species under study, motivating the ongoing efforts to establish a comprehensive terahertz spectral database of representative pigments. Standard archived spectra are typically acquired at room temperature and susceptible to spectral broadening, which often renders pigment identification difficult, if not impossible. In this paper, we report the frequencies of the vibrational modes of minium (PbO, red lead) by performing terahertz time-domain spectroscopy at room temperature and also at low temperatures. Clear absorption peaks appear at 54.9, 62.1, 71.3, and 83.9 cm at room temperature and blue-shift as the temperature decreases. In addition, new absorption peaks of 59.8 and 66.4 cm are observed below 150 K, which signify a structural phase transition occurring at 170 K in minium. Our results are expected to enhance our understanding of the vibrational activity of minium and suggest a future direction for how to improve and refine the existing terahertz spectral databases for pigment analysis.
太赫兹光谱已越来越多地被用作艺术品诊断、分析和修复的有效无损工具。特别是对于艺术家颜料而言，太赫兹探测器揭示了所研究特定颜料种类特有的振动模式，这促使人们不断努力建立一个具有代表性颜料的综合太赫兹光谱数据库。标准存档光谱通常在室温下获取，并且容易出现光谱展宽，这常常使颜料识别变得困难，甚至无法识别。在本文中，我们通过在室温和低温下进行太赫兹时域光谱，报告了铅丹（PbO，红丹）振动模式的频率。在室温下，54.9、62.1、71.3和83.9厘米处出现清晰的吸收峰，并且随着温度降低发生蓝移。此外，在150 K以下观察到59.8和66.4厘米处的新吸收峰，这表明铅丹在170 K时发生了结构相变。我们的结果有望增进我们对铅丹振动活性的理解，并为如何改进和完善现有的用于颜料分析的太赫兹光谱数据库指明未来方向。
