Determining the complex refractive index of cellulose nanocrystals by combination of Beer-Lambert and immersion matching methods

Niskanen, Ilpo; Suopajärvi, Terhi; Fabritius, Tapio; Heikkilä, Rauno; Thungström, Göran

doi:10.1016/j.jqsrt.2019.06.023

Cited by 46 publications

(23 citation statements)

References 32 publications

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“…After applying the methods, the absorption coefficient of the films was determined by the Beer-Lambert Method [38]. For the 120 min films, the Envelope Method was also used for the purpose of comparing the behavior of the curves for the functions of the coefficient found, and then the Bandgap of the films by the Tauc method was found.…”

Section: Methodsmentioning

confidence: 99%

Optical-Electrical Properties and Thickness Analysis of TiO2 Thin Films Obtained by Magnetron Sputtering

Sobrinho¹,

Neto

Lima

et al. 2020

Braz J Phys

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The study of thin films with properties that meet specific needs and improve people's quality of life has been the focus of many researchers. However, knowing and controlling the production techniques of these films have been a challenge for the industry of optical-electronic devices, functional coatings, and energy conservation. The thickness of thin films is a parameter that influences the optical and electrical characteristics of these materials, thus being one of the most important information in the plasma deposition process. Because of the need for precision in measuring the thickness of thin transparent films, this work proposes to evaluate the Swanepoel methods (envelope) and the PUMA, computational method, from optical transmittance curves and compare them with the measurements directly made by microscopy. Scanning electronics for thin films of TiO 2 deposited by magnetron sputtering in different conditions. The results of this study showed that the PUMA method is capable of calculating film thicknesses of a few hundred nanometers and with few interference fringes. The PUMA method showed convergence with high precision for films produced with 30 and 60 min of treatment and a difference of 17% for films with 120 min of deposition concerning the measurements made by microscopy.

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Section: Methodsmentioning

confidence: 99%

Optical-Electrical Properties and Thickness Analysis of TiO2 Thin Films Obtained by Magnetron Sputtering

Sobrinho¹,

Neto

Lima

et al. 2020

Braz J Phys

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“…There are various experimental methods for RI measurement of holocellulose in the condensed/dense form (fibers, powder, pressed, etc.). [ 19–23 ] However, such values might differ from an effective RI of the TW, which is of practical importance for the application development. The RI of delignified wood can also be estimated using solvent‐assisted methods, [ 24 ] although considerable experimental work is required.…”

Section: Introductionmentioning

confidence: 99%

Light Propagation in Transparent Wood: Efficient Ray‐Tracing Simulation and Retrieving an Effective Refractive Index of Wood Scaffold

Pang

Baitenov

Montanari

et al. 2021

Advanced Photonics Research

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Transparent wood (TW), a biocomposite material demonstrating optical transparency in the visible range, has attracted much interest in recent years due to great potential for ecofriendly applications, for instance, in construction industry and functionalized organic materials. Optical properties of TW, including transparency and haze, depend on a particular structure of cellulose‐based backbone compound, (mis‐)matching of the refractive indices (RIs) between TW compounds, and the polymer matrix. Although there are data of cellulose RIs for various forms of cellulose (fibers, powder, hot‐pressed films, etc.), these values might differ from an effective RI of the TW substrate. Herein, a numerical model of light propagation in the TW, based on the real cellular structure in wood, is presented and applied to estimate an effective RI of the delignified wood reinforcement in the experimentally investigated TW material. Ray‐tracing and rigorous electromagnetic approaches are compared for modeling light propagation in the TW. Ray tracing demonstrates considerably simplified yet accurate and efficient solutions. The work brings substantial progress toward realistic and practical wood modeling for the purpose of applications, materials design, and fundamental studies.

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“…The optical properties of nanocellulose are important parameters for films and nanopapers, and they may also be affected by elevated temperatures (thermal stress) (Pakharenko et al 2021). The optical properties of nanocellulose films have been commonly investigated by analysing the reflection, absorption, scattering or polarisation of light to obtain different variables, such as transmittance (Sun et al 2018), complex refractive index (Niskanen et al 2019b), optical activity (Zlenko et al 2019), colour (Vardanyan et al 2015), birefringence (Orellana et al 2018), opacity (Zhu et al 2011), and gloss (Kong et al 2019). The knowledge of the transformation of the optical characteristics of nanocellulose materials as a function of temperature is still incomplete, and the previous studies have mainly addressed the colour of cellulose nanomaterials (Pakharenko et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…In our previous work, we developed a method of determining the complex refractive index of cellulose nanocrystals (CNCs) as a function of wavelength by combining the Beer-Lambert and immersion-matching methods (Niskanen et al 2019b). The sizes of nanocelluloses (CNCs and CNFs) were in turn analysed using Rayleigh approximation and the Mie theory (Niskanen et al 2019a).…”

Section: Introductionmentioning

confidence: 99%

Alteration of the Optical and Mechanical Characteristics of Cellulose Nanofibre Films Under Thermal Treatment

Niskanen

Zhang

Liimatainen

et al. 2021

Preprint

Self Cite

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Nanocelluloses and their different designs, such as films and nanopapers, have gained considerable interest in many application areas due to their unique properties. For many purposes, such as for packaging and electronics, the thermal stability of nanocellulose materials is a crucial characteristic. In this study, the effects of heat treatment (100ºC, 150ºC and 200ºC) on the optical and mechanical properties of 2,2,6,6-tetramethylpiperidinyl-1-oxy radical-oxidised cellulose nanofibre (TO-CNF) films were investigated, especially the alteration of the colour, complex refractive index and birefringence of the films. Exposing TO-CNF films to high temperatures (> 150ºC) induced permanent transformations in the CNF structure, leading to an increase in the refractive index, decreases in the birefringence and crystallinity index, colour darkening and significant deterioration of the mechanical properties.

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Determining the complex refractive index of cellulose nanocrystals by combination of Beer-Lambert and immersion matching methods

Cited by 46 publications

References 32 publications

Optical-Electrical Properties and Thickness Analysis of TiO2 Thin Films Obtained by Magnetron Sputtering

Optical-Electrical Properties and Thickness Analysis of TiO2 Thin Films Obtained by Magnetron Sputtering

Light Propagation in Transparent Wood: Efficient Ray‐Tracing Simulation and Retrieving an Effective Refractive Index of Wood Scaffold

Alteration of the Optical and Mechanical Characteristics of Cellulose Nanofibre Films Under Thermal Treatment

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