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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Photolysis of CH3CN Ices by Soft X-rays: Implications for the Chemistry of Astrophysical Ices at the Surroundings of X-ray Sources

Full text
Author(s):
Carvalho, G. A. [1] ; Pilling, S. [1]
Total Authors: 2
Affiliation:
[1] Univ Vale Paraiba UNIVAP, Inst Pesquisa & Desenvolvimento IP&D, BR-12244000 Sao Jose Dos Campos, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Journal of Physical Chemistry A; v. 124, n. 41, p. 8574-8584, OCT 15 2020.
Web of Science Citations: 1
Abstract

In this work, broad-band soft X-ray (6-2000 eV) was employed to irradiate frozen acetonitrile CH3CN, at the temperature 13 K, with different photon fluences up to 1.5 x 10(18) photons cm(-2). Here, acetonitrile is considered as a representative complex organic molecule (COM) present in astrophysical water-rich ices. The experiments were conduced at the Brazilian synchrotron facility (LNLS/CNPEM) employing infrared spectroscopy (FTIR) to monitor chemical changes induced by radiation. The effective destruction cross section of acetonitrile and effective formation cross section for daughter species formed inside the ice were obtained. The identified radiation products were HCN, CH4, H2CCNH, and CH3NC showing that fragmentation and rearrangement contribute to acetonitrile destruction. Chemical equilibrium and molecular abundances at this stage were determined, which also includes the abundance estimates of unknown molecules, produced but not directly detected, in the ice. The chemical equilibrium was reached at fluence around 1.5 x 10(18) photons cm(-2). Time scales for ices, at hypothetical snow line distances, to reach chemical equilibrium around compact objects, young stellar objects, and O/B stars and inside solar system were given. Among the obtained results are the time scales for reaching chemical equilibrium around different astronomical strong X-ray emitters, e.g., 14 days (for the Sun at 5 AU), 41 and 82 days (for O/B stars at 5 AU), 10(9)-10(11) years (for white dwarfs at 1 LY), 450 years (for Crab pulsar at 2.25 LY), around 10(7) years (for Vela pulsar at 2.25 LY), and 7.5 x 10(6) years (for Sagittarius A{*} at 3 LY). (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
FAPESP's process: 15/10492-3 - Study about the chemical evolution of astrophysical ices in the vicinity of young stellar objects employing experimental data in the infrared and computational modeling codes
Grantee:Will Robson Monteiro Rocha
Support Opportunities: Scholarships in Brazil - Post-Doctoral