Chemical Identification in the Specular and Off-Specular Rough-Surface Scattered Terahertz Spectra Using Wavelet Shrinkage
We present the development and implementation of a novel wavelet shrinkage technique for the retrieval of obscured characteristic resonant signatures in the scattered terahertz (THz) reflectivity of molecular crystals. In this implementation, the wavelet basis functions associated with the absorptio...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
IEEE
2021-01-01
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| Series: | IEEE Access |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/9354630/ |
| _version_ | 1818932206926561280 |
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| author | Mahmoud E. Khani M. Hassan Arbab |
| author_facet | Mahmoud E. Khani M. Hassan Arbab |
| author_sort | Mahmoud E. Khani |
| collection | DOAJ |
| description | We present the development and implementation of a novel wavelet shrinkage technique for the retrieval of obscured characteristic resonant signatures in the scattered terahertz (THz) reflectivity of molecular crystals. In this implementation, the wavelet basis functions associated with the absorption features were identified using the second-order total variation of the wavelet coefficients. Additionally, wavelet coefficients at certain scales were modified using the phase function corrections and wavelet hard thresholding. Reconstruction of the original spectra using these modified wavelet coefficients yielded the exact resonant frequencies of the chemicals, which were otherwise unrecognizable in the spectral artifacts of the rough surface scattering. We examined the robustness of this method over controlled levels of rough surface scattering, validated using the Kirchhoff approximation, in spectroscopic targets made from α-lactose monohydrate and 4-aminobenzoic acid (PABA), which have close spectral lines. We successfully retrieved the spectral absorption fingerprints in both specular and off-specular reflection geometries. This technique can be utilized for stand-off material characterization using the THz reflection spectroscopy in uncontrolled environments and potentially can be adopted for other broadband spectroscopic modalities. |
| first_indexed | 2024-12-20T04:28:49Z |
| format | Article |
| id | doaj.art-17ac8783dee3483e8acd7583a6a48f4c |
| institution | Directory Open Access Journal |
| issn | 2169-3536 |
| language | English |
| last_indexed | 2024-12-20T04:28:49Z |
| publishDate | 2021-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Access |
| spelling | doaj.art-17ac8783dee3483e8acd7583a6a48f4c2022-12-21T19:53:26ZengIEEEIEEE Access2169-35362021-01-019297462975410.1109/ACCESS.2021.30594249354630Chemical Identification in the Specular and Off-Specular Rough-Surface Scattered Terahertz Spectra Using Wavelet ShrinkageMahmoud E. Khani0https://orcid.org/0000-0002-3058-6247M. Hassan Arbab1https://orcid.org/0000-0002-6565-3358Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USADepartment of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USAWe present the development and implementation of a novel wavelet shrinkage technique for the retrieval of obscured characteristic resonant signatures in the scattered terahertz (THz) reflectivity of molecular crystals. In this implementation, the wavelet basis functions associated with the absorption features were identified using the second-order total variation of the wavelet coefficients. Additionally, wavelet coefficients at certain scales were modified using the phase function corrections and wavelet hard thresholding. Reconstruction of the original spectra using these modified wavelet coefficients yielded the exact resonant frequencies of the chemicals, which were otherwise unrecognizable in the spectral artifacts of the rough surface scattering. We examined the robustness of this method over controlled levels of rough surface scattering, validated using the Kirchhoff approximation, in spectroscopic targets made from α-lactose monohydrate and 4-aminobenzoic acid (PABA), which have close spectral lines. We successfully retrieved the spectral absorption fingerprints in both specular and off-specular reflection geometries. This technique can be utilized for stand-off material characterization using the THz reflection spectroscopy in uncontrolled environments and potentially can be adopted for other broadband spectroscopic modalities.https://ieeexplore.ieee.org/document/9354630/Chemical identificationmaximal overlap discrete wavelet transform (MODWT)phase function effectspyramid algorithmreflection-mode spectroscopyrough surface scattering |
| spellingShingle | Mahmoud E. Khani M. Hassan Arbab Chemical Identification in the Specular and Off-Specular Rough-Surface Scattered Terahertz Spectra Using Wavelet Shrinkage IEEE Access Chemical identification maximal overlap discrete wavelet transform (MODWT) phase function effects pyramid algorithm reflection-mode spectroscopy rough surface scattering |
| title | Chemical Identification in the Specular and Off-Specular Rough-Surface Scattered Terahertz Spectra Using Wavelet Shrinkage |
| title_full | Chemical Identification in the Specular and Off-Specular Rough-Surface Scattered Terahertz Spectra Using Wavelet Shrinkage |
| title_fullStr | Chemical Identification in the Specular and Off-Specular Rough-Surface Scattered Terahertz Spectra Using Wavelet Shrinkage |
| title_full_unstemmed | Chemical Identification in the Specular and Off-Specular Rough-Surface Scattered Terahertz Spectra Using Wavelet Shrinkage |
| title_short | Chemical Identification in the Specular and Off-Specular Rough-Surface Scattered Terahertz Spectra Using Wavelet Shrinkage |
| title_sort | chemical identification in the specular and off specular rough surface scattered terahertz spectra using wavelet shrinkage |
| topic | Chemical identification maximal overlap discrete wavelet transform (MODWT) phase function effects pyramid algorithm reflection-mode spectroscopy rough surface scattering |
| url | https://ieeexplore.ieee.org/document/9354630/ |
| work_keys_str_mv | AT mahmoudekhani chemicalidentificationinthespecularandoffspecularroughsurfacescatteredterahertzspectrausingwaveletshrinkage AT mhassanarbab chemicalidentificationinthespecularandoffspecularroughsurfacescatteredterahertzspectrausingwaveletshrinkage |