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Measuring the Aerosol Light Absorption Coefficient - a Not-So-Easy Task With Relevance for the Global and Regional Climate
Griša Močnik, 2022, unpublished invited conference lecture

Abstract: The photothermal interferometer measurement of aerosol absorption, using pump lasers (532, 1064 nm) and phase sensitive detection results in 4 and 6% measurement uncertainty. It is calibrated traceably to primary standards and thereby a potential reference.
Keywords: aerosol absorption, black carbon, climate change
Published in RUNG: 20.07.2022; Views: 1560; Downloads: 0
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35.
Measuring aerosol absorption directly - PTI methods to the rescue
Griša Močnik, unpublished invited conference lecture

Keywords: aerosol absorption, black carbon, climate change
Published in RUNG: 19.07.2022; Views: 1455; Downloads: 0
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Optical emission diagnosis of carbon nanoparticle incorporated chlorophyll for sensing applications
Mohanachandran Nair Sindhu Swapna, RAJ VIMAL, SARITHA DEVI H V, Sankararaman S, 2019, original scientific article

Abstract: Chlorophyll fluorescence (Chl F) is widely used in sensing applications to understand terrestrial vegetation and environmental and climatic variations. The increasing rates of industrialization and carbon emission from internal combustion engines (ICEs) pose a threat to sustainable development. This study analyses the impact of carbon nanoparticles (CNPs) from ICEs on the optical absorption and fluorescence emission of leaf pigments. Leaf pigments without and with CNPs were subjected to UV-visible and photo-luminescence (PL) spectroscopy analyses. The field emission scanning electron microscopy and high-resolution transmission electron microscopy images of CNPs showed their morphology. The Jablonski diagram of the CNP-incorporated chlorophyll system helped in understanding the fluorescence emission,internal conversion, and the exchange of energy between them. The variations in (i) total chlorophyll, (ii) optical absorbance by total chlorophyll, (iii) PL emission peak (at 675 nm and 718 nm) intensities for different excitation wavelengths, and (iv) normalized absorbance at the PL emission peaks with different CNP concentrations were analysed by dividing into three regions. In Region I (0–0.625 mg ml−1 ), the radiative component dominated the nonradiative component as a result of energy transfer from CNPs to chlorophyll. In Region II (0.625–1.2 mg ml−1 ), the increase in CNP concentration initiated diffusion into chloroplasts, resulting in the increase in the nonradiative part of total energy and decrease in PL peak intensity. In Region III (1.2–2.5 mg ml−1 ), the energy absorbed by the CNPs dissipated more nonradiatively, leading to a slow rate of increase in the radiative part. The visual response of PL emission, color purity, and the distribution of the emitted energy over the spectrum studied with the help of CIE plots, power spectrum, and confocal fluorescence microscopy revealed the fluorescence emission in the red region. This study suggests the possibility of employing Chl F in agricultural, environmental, and biological fields for sensing applications.
Keywords: carbon nanoparticle, optical emission, fluorescence
Published in RUNG: 05.07.2022; Views: 1298; Downloads: 0
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39.
Order fluctuation induced tunable light emission from carbon nano system
Mohanachandran Nair Sindhu Swapna, Sankararaman S, 2019, original scientific article

Abstract: The paper reports the thermal-induced order fuctuations, in a carbon nanosystem with carbon nanotubes (CNTs) synthesized by the incomplete combustion of gingelly oil. The sample annealed at diferent temperatures (30–400 °C) is subjected to various morphological and spectroscopic characterizations. The ultraviolet–visible spectroscopic and thermogravimetric analyses reveal the CNTs in the sample. The high-resolution transmission electron microscopy (HR-TEM) also confrms the formation of CNTs in the sample. The Raman spectrum and X-ray difraction pattern show the signature of multi-walled to single-walled CNT transformation and thus an order fuctuation on annealing. The quantum yield of the sample, measured by integrating sphere method, yields 46.15% at an emission wavelength of 575 nm. When the excitation wavelength is varied from 350 to 510 nm, the CIE coordinate moves from the white region to the yellowish-green region. The varying amount of CNTs in the soot, upon annealing is found to vary the luminescence emission from the sample. The study reveals the thermal-induced oscillatory order in carbon nanosystem with carbon nanotubes (CNTs) leading to tunable excitation/ thermal-dependent luminescence emission and thereby suggesting the possibility of converting the futile soot for fruitful applications in photonics and nanoelectronics.
Keywords: Carbon nanosystem, Single-walled carbon nanotubes, Multi-walled carbon nanotubes, Raman spectroscopy, Thermogravimetric analysis, CIE plot, Quantum yield, gingelly oil
Published in RUNG: 05.07.2022; Views: 1440; Downloads: 0
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40.
Carbon nanoparticles assisted energy transport mechanism in leaves: A thermal lens study
Mohanachandran Nair Sindhu Swapna, 2019, original scientific article

Abstract: In the world of increasing population and pollution due to carbon emissions, the research for effective utilization of futile diesel soot for fruitful applications has become a necessity for a sustainable development. The contribution to pollution from vehicles and industries due to the aging of engines has caused a crisis. Carbon nanoparticles (CNPs) have been the subject of interest because of their good physical, chemical, and biological properties. The present work investigates the role of CNPs produced by internal combustion engines on the energy transport mechanism among leaf pigments using the sensitive and nondestructive single beam thermal lens technique. The studies reveal the absorption changes by various chlorophyll pigments with the concentration of CNPs sprayed on the leaves. Though for low concentrations CNPs lower the photon absorbance by chlorophyll pigments, the effect gets reversed at higher concentrations. The variation of thermal diffusivity with CNP concentration and its role in the energy transport mechanism among chlorophyll pigments are also studied. It is found that CNP concentrations of 625-2500mg/l are good for better intra-pigment energy transport leading to increased rate of photosynthesis and plant yield and thereby helping in attaining food security. The variation of CNP assisted energy transport among leaf pigments on the production of nicotinamide adenine dinucleotide phosphate (NADPH) and carbohydrates is also studied with ultraviolet (UV) and near-infrared (NIR) spectroscopy.
Keywords: carbon nanoparticle, soot, energy transport, thermal lens, photosynthesis
Published in RUNG: 05.07.2022; Views: 1311; Downloads: 0
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