Terahertz vibrational modes of sodium magnesium chlorophyllin and chlorophyll in plant leaves
Coquillat, Dominique and O'Connor, Emma and Brouillet, Etienne V. and Meriguet, Yoann and Bray, Cédric and Nelson, David J. and Faulds, Karen and Torres, Jeremie and Dyakonova, Nina (2023) Terahertz vibrational modes of sodium magnesium chlorophyllin and chlorophyll in plant leaves. Journal of Infrared, Millimeter and Terahertz Waves, 44 (3-4). 245–264. ISSN 1866-6906 (https://doi.org/10.1007/s10762-023-00905-6)
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Abstract
The low-frequency (terahertz) vibrational spectroscopy has been investigated experimentally for two chlorophyll species, Chl- and one of its magnesium derivatives (Chl-Mg-Na). The combination of terahertz time-domain spectroscopy and Fourier transform infrared spectroscopy has enabled a broad frequency range to be covered (0.2 to 18 THz). For Chl-Mg-Na, the terahertz spectra show clear and well-marked features at 1.44, 1.64, and 1.83 THz dominated by intermolecular interactions. The frequency dependent refractive index and absorption coefficient of Chl-Mg-Na were both determined using the Fit@TDS software. Below 1.0 THz, a refractive index of 2.09 was measured. In order to acquire further understanding of the observed vibrational modes, a detailed study of the temperature dependence of the line positions of the lowest modes in Chl-Mg-Na was performed. As the temperature was increased from 88 K to 298 K, the feature at 1.83 THz experienced a notable red shift of frequency and line shape broadening, whereas the feature at 1.44 THz showed little change. These results suggest that the 1.83 THz feature is dominated by intermolecular motions occurring over the crystalline unit cell of the Chl-Mg-Na molecular crystal. Finally, terahertz time-domain spectroscopy was used to acquire the spectra of an ornamental plant bearing yellow-green variegated leaves (ivy, Aureomarginata variety), the yellow sectors having lower chlorophyll content compared to the green sectors. In dehydrated green tissue, the chlorophyll molecules showed well-marked intermolecular vibrational modes at 1.86 THz, indicating that chlorophyll molecules are prone to packing with an ordered molecular arrangement. These results demonstrate the potential application of THz spectroscopy in the field of agronomy.
ORCID iDs
Coquillat, Dominique, O'Connor, Emma, Brouillet, Etienne V. ORCID: https://orcid.org/0000-0001-5854-1983, Meriguet, Yoann, Bray, Cédric, Nelson, David J. ORCID: https://orcid.org/0000-0002-9461-5182, Faulds, Karen ORCID: https://orcid.org/0000-0002-5567-7399, Torres, Jeremie and Dyakonova, Nina;-
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Item type: Article ID code: 83755 Dates: DateEvent1 April 2023Published27 January 2023Published Online13 January 2023AcceptedSubjects: Science > Chemistry > Organic chemistry Department: Faculty of Science > Pure and Applied Chemistry
Strategic Research Themes > Health and Wellbeing
Technology and Innovation Centre > BionanotechnologyDepositing user: Pure Administrator Date deposited: 19 Jan 2023 13:36 Last modified: 29 Nov 2024 01:19 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/83755