Open AccessTerahertz Spectroscopic Analysis of the Vermilion Pigment in Free-Standing and Polyethylene-Mixed Forms
Author(s) -
Ji Eun Lee,
Howon Lee,
Jangwon Kim,
Taek Sun Jung,
Jonghyeon Kim,
Na Yeon Baek,
You Na Song,
Han Hyoung Lee,
Jae-Hoon Kim
Publication year - 2021
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.1c01336
Subject(s) - vermilion , materials science , polyethylene , terahertz radiation , spectroscopy , spectral line , pigment , analytical chemistry (journal) , optics , optoelectronics , chemistry , composite material , organic chemistry , physics , quantum mechanics , astronomy
Terahertz spectroscopy can be utilized as an effective nondestructive identification tool for the study of artist's pigments. Consequently, extensive measurements have been conducted on representative pigment species, and a few terahertz spectral databases have been constructed. However, the reported spectra were often acquired from pigment samples mixed with polyethylene at room temperature with low resolution, which often led to low-quality spectra with unresolved overlapping lines further broadened due to thermal effects. Here, we present our study of vermilion (HgS, mercury sulfide) as an illustration of how we can overcome such difficulties by studying free-standing oil-paint samples at room temperature and then by performing low-temperature measurements on polyethylene-mixed samples to minimize line broadening due to thermal effects. Our results identify clearly resolved absorption peaks due to lattice vibrations of vermilion at 40.4, 44.5, and 89.9 cm -1 at 2 K. The temperature dependence of the peak shift and line broadening reveals anharmonic characteristics of these lattice vibrational modes. Our approach will definitely suggest new ways to improve and enhance existing terahertz spectral databases of ancient and modern pigments toward actual analysis, diagnosis, and conservation of heritage artworks.