Morphologies, compositions and spectrum features of palm leaves

Liu, Yike; Liu, Yutong; Xu, Xin­guang; Wei, Yanying; Ma, Mingming; Hong-Zhao, Zhu; Chun-Qian, Ma; Rui-Jiao, Zou; Ding, Lixin; Luo, Min

doi:10.7498/aps.64.068701

Cited by 3 publications

(1 citation statement)

References 20 publications

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“…An attractive feature of THz probing of chlorophyll in plants is i) its non-invasive character which allows the measurement on leaves during long periods of time, ii) the relatively low scattering losses due to long wavelengths compared to the leaf roughness [23], iii) the possibility to probe all the chlorophyll located in the different layers of the leaf. Surprisingly, to the best of our knowledge, only a few reports are available of attempts to discover chlorophyll-𝑎 (Chl-𝑎) ngerprint in plant leaves at THz frequencies [21,24]. Chlorophyll is a group of fatsoluble magnesium porphyrin complex which is widely found in green sectors of plants.…”

Section: Introductionmentioning

confidence: 99%

Terahertz Vibrational Modes of Sodium Magnesium Chlorophyllin and Chlorophyll in Plant Leaves

Coquillat

O'Connor

Brouillet

et al. 2023

J Infrared Milli Terahz Waves

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The low-frequency (terahertz) vibrational spectroscopy of two chlorophyll species, Chl-𝑎 and one of its magnesium derivatives (Chl-Mg-Na), has been investigated experimentally. 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 coe cient of Chl-Mg-Na were 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 is increased from 88 K to 298 K, the feature at 1.83 THz experiences a notable red shift of frequency and line shape broadening, whereas the feature at 1.44 THz shows 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 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 green sectors. In dehydrated green tissue, the chlorophyll molecules showed well-marked intermolecular vibrational modes at 1.85 THz, indicating that chlorophyll molecules are prone to pack with an ordered molecular arrangement. These results demonstrate the potential application of THz spectroscopy in agricultural sciences.

show abstract

Section: Introductionmentioning

confidence: 99%

Terahertz Vibrational Modes of Sodium Magnesium Chlorophyllin and Chlorophyll in Plant Leaves

Coquillat

O'Connor

Brouillet

et al. 2023

J Infrared Milli Terahz Waves

View full text Add to dashboard Cite

show abstract

Terahertz Vibrational Modes of Sodium Magnesium Chlorophyllin and Chlorophyll in Plant Leaves

Coquillat

O'Connor

Brouillet

et al. 2022

Preprint

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The low-frequency (terahertz) vibrational spectroscopy of two chlorophyll species, Chl-𝑎 and one of its magnesium derivatives (Chl-Mg-Na), has been investigated experimentally. 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 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 is increased from 88 K to 298 K, the feature at 1.83 THz experiences a notable red shift of frequency and line shape broadening, whereas the feature at 1.44 THz shows 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 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 green sectors. In dehydrated green tissue, the chlorophyll molecules showed well-marked intermolecular vibrational modes at 1.85 THz, indicating that chlorophyll molecules are prone to pack with an ordered molecular arrangement. These results demonstrate the potential application of THz spectroscopy in agricultural sciences.

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Experimental and theoretical study on terahertz spectra of all-trans -carotene

Yan¹,

Ma²,

Zelin³

et al. 2017

Acta Phys. Sin.

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The -carotene is a short chain polyene molecule containing nine -electron conjugated double-bonds. Because of its special molecular structure, -carotene has been used widely in many fields, including functional materials, optoelectronic devices and biological applications of light collection, light protection, anti-cancer, etc. Recently, new applications of -carotene in generation and detection of terahertz (THz) wave have also attracted great attention. In this work, all-trans -carotene films are prepared by spray coating, and the THz spectra in a wavenumber range of 30-400 cm-1 (a frequency range of 0.9-12 THz) of the as-prepared products are experimentally measured at room temperature by Fourier transform infrared spectroscopy. For comparison, the THz spectra in 0.5-3.0 THz are also characterized at the same temperature by THz time-domain spectroscopy. Based on these measurements, the fingerprint peaks of all-trans -carotene in the THz region are experimentally identified to be located at 54 cm-1 (1.62 THz), 57 cm-1 (1.71 THz), 64 cm-1 (1.91 THz), 77 cm-1 (2.32 THz), 90 cm-1 (2.69 THz), 98 cm-1 (2.95 THz), 115 cm-1 (3.45 THz), 124 cm-1 (3.72 THz), 134 cm-1 (4.02 THz), 170 cm-1 (5.11 THz), 247 cm-1 (7.42 THz), and 279 cm-1 (8.38 THz), respectively. It is worth noting that the recent results about the THz spectra of palm leaves are thus verified. Particularly, the B3 LYP method of density functional theory is further utilized in this work to theoretically simulate the THz spectra of all-trans -carotene molecule. It is revealed that the theoretical simulation results accord well with those experimentally measured data. In addition, we also find that the absorption peaks are caused by the torsion, deformation and rocking vibration of the molecules. Accordingly, the vibrational modes of the measured THz characteristic peaks at 148 cm-1 (4.44 THz), 132 cm-1 (3.96 THz), 115 cm-1 (3.45 THz), 76 cm-1 (2.28 THz) and 52 cm-1 (1.56 THz) are theoretically assigned, which provides a reference to explain the formation mechanism of the THz spectra. The valuable results presented in this work will be helpful for promoting the studies of the THz spectral features and response mechanisms of the organics.

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Morphologies, compositions and spectrum features of palm leaves

Cited by 3 publications

References 20 publications

Terahertz Vibrational Modes of Sodium Magnesium Chlorophyllin and Chlorophyll in Plant Leaves

Terahertz Vibrational Modes of Sodium Magnesium Chlorophyllin and Chlorophyll in Plant Leaves

Terahertz Vibrational Modes of Sodium Magnesium Chlorophyllin and Chlorophyll in Plant Leaves

Experimental and theoretical study on terahertz spectra of all-trans -carotene

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