| Full text | |
| Author(s): |
Total Authors: 2
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| Affiliation: | [1] Univ Vale Paraiba, Sao Jose Dos Campos, SP - Brazil
Total Affiliations: 1
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| Document type: | Journal article |
| Source: | SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 123, p. 436-446, APR 5 2014. |
| Web of Science Citations: | 13 |
| Abstract | |
We present a code, called NKABS, to determine optical constants (complex refractive index) of thin films directly from the absorbance data in the infrared. The code is written in the Python language, which is more accurate and faster than previous methods in the literature. For solving the Kramers-Kronig relationship, we used the Maclaurin's methodology. Unlike other codes, which found convergence in 30-40 iterations, the NKABS reach the convergence in just 4 or 5 iterations. Additionally, to evaluate the error, this code calculates the MAPE (Mean Absolute Percentage Error) and the chi-square chi(2). The typical MAPE error obtained using NKABS is less than 1 x 10(-3)%. To illustrate the functionality of this code, we calculate the optical constants in the infrared spectral region of 28 different samples of astrophysical interest at different temperatures (10-300 K), which simulates molecules in space environments, mostly the ones called astrophysical ices. The samples were obtained from the condensation of pure gases (e.g. CO, CO2, NH3, SO2), from the sublimation in vacuum of pure liquids (e.g. water, acetone, acetonitrile, acetic acid, formic acid, ethanol and methanol) and from mixtures of different species (e.g. H2O:CO2, H2O:CO:NH3, H2O:CO2:NH3:CH4). Additionally films of solid biomolecules samples of astrochemistry/astrobiology interest (e.g. glycine, adenine) were probed. The code and the data-base obtained here are available on-line. The NKABS can also be employed to calculate refractive index of processed samples (by heating or radiation). Such data and the refractive index of virgin samples are required as input in several astrophysical models that calculate the radiative transfer in dusty astrophysical environments such as protoplanetary disks and circumstellar environments as well as dense molecular clouds. (C) 2013 Elsevier B.V. All rights reserved. (AU) | |
| FAPESP's process: | 13/07657-5 - Computational modeling of circumstellar environment of protostars by employing data of bombarded ices with cosmic rays simulated in laboratory. |
| Grantee: | Will Robson Monteiro Rocha |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 09/18304-0 - Synthesis and degradation of prebiotic molecular species at planetary atmospheres, comets and interstellar ice analogs |
| Grantee: | Sergio Pilling Guapyassu de Oliveira |
| Support Opportunities: | Research Grants - Young Investigators Grants |