Estimation of optical properties of neuroendocrine pancreas tumor with double-integrating-sphere system and inverse Monte Carlo model

(1) Background: This study investigated the miscibility of carbon-based fillers within industrial scale polymers for the preparation of superior quality polymer composites. It focuses on finding the light distribution in gamma irradiated ultra-high molecular weight polyethylene (UHMWPE). (2) Methods: The Kubleka–Munk model (KMM) was used to extract the optical properties, i.e., absorption coefficients (μa) and scattering coefficients (μs). Samples amounting to 30 kGy and 100 kGy of irradiated (in the open air) UHMWPE from 630 nm to 800 nm were used for this purpose. Moreover, theoretical validation of experimental results was performed while using extracted optical properties as inputs for the Monte Carlo model of light transport (MCML) code. (3) Conclusions: The investigations revealed that there was a significant decrease in absorption and scattering coefficient (μa & μs) values with irradiation, and 30 kGy irradiated samples suffered more compared to 100 kGy irradiated samples. Furthermore, the simulation of light transport for 800 nm showed an increase in penetration depth for UHMWPE after gamma irradiation. The decrease in dimensionless transport albedo μs(μa+μs) from 0.95 to 0.93 was considered responsible for this increase in photon absorption per unit area with irradiation. The report results are of particular importance when considering the light radiation (from 600 nm to 899 nm) for polyethylene modification and/or stabilization via enhancing the polyethylene chain mobility.

Download Full-text

Energy transport in conjugated polymers: electronic structure and kinetic Monte Carlo simulations

10.21826/viiiseedmol202076 ◽

2020 ◽

Author(s):

Laura Simonassi Raso de Paiva ◽

Leonardo Evaristo de Sousa ◽

Pedro Henrique de Oliveira Neto

Keyword(s):

Monte Carlo ◽

Optical Properties ◽

Conjugated Polymers ◽

Energy Transport ◽

Kinetic Monte Carlo ◽

Monte Carlo Model ◽

Active Materials ◽

Exciton Diffusion ◽

Polymeric Chains ◽

Kinetic Monte Carlo Simulations

Conjugated polymers are materials that have attracted much attention from the research community because of their charge and energy transport properties. In this sense, it is necessary to understand the mechanism behind exciton transfer in this particular class of systems. However, direct application of procedures done for different organic compounds is not straightforward for long polymeric chains, because such procedures would be computationally impracticable. In that matter, alternative treatments are required. In this work, we perform spectrum simulations for poly-thiophene (PTH) and poly(p-phenylene vinylene) (PPV) chains by analyzing the evolution of electronic properties with oligomer sizes and its effects on exciton diffusion. Furthermore, employing a kinetic Monte Carlo model, we also investigate the efficiency of intrachain exciton diffusion. Our results show a reliable description of the optical properties for long polymeric chains, and a comparison is made between the different approaches in describing the optical properties of such polymers. This study may be useful in the development of more sophisticated optoelectronic devices that use conjugated polymers as its active materials.

Download Full-text