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Mackie CJ, Candian A, Lee TJ, Tielens AGGM. Anharmonicity and the IR Emission Spectrum of Neutral Interstellar PAH Molecules. J Phys Chem A 2022; 126:3198-3209. [PMID: 35544706 DOI: 10.1021/acs.jpca.2c01849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The characteristics of the CH stretching and out-of-plane bending modes in polycyclic aromatic hydrocarbon molecules are investigated using anharmonic density functional theory (DFT) coupled to a vibrational second-order perturbation treatment taking resonance effects into account. The results are used to calculate the infrared emission spectrum of vibrationally excited species in the collision-less environment of interstellar space. This model follows the energy cascade as the molecules relax after the absorption of a UV photon in order to calculate the detailed profiles of the infrared bands. The results are validated against elegant laboratory spectra of polycyclic aromatic hydrocarbon absorption and emission spectra obtained in molecular beams. The factors which influence the peak position, spectral detail, and relative strength of the CH stretching and out-of-plane bending modes are investigated, and detailed profiles for these modes are derived. These are compared to observations of astronomical objects in space, and the implications for our understanding of the characteristics of the molecular inventory of space are assessed.
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Affiliation(s)
- Cameron J Mackie
- Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alessandra Candian
- van 't Hoff Institute for Molecular Science, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands
| | - Timothy J Lee
- NASA Ames Research Center, Moffett Field, California 94035-1000, United States
| | - Alexander G G M Tielens
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands.,Astronomy Department, University of Maryland, College Park, Maryland 20742, United States
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2
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Lacinbala O, Calvo F, Dubosq C, Falvo C, Parneix P, Rapacioli M, Simon A, Pino T. Radiative relaxation in isolated large carbon clusters: Vibrational emission versus recurrent fluorescence. J Chem Phys 2022; 156:144305. [DOI: 10.1063/5.0080494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recurrent fluorescence (RF) from isolated carbon clusters containing between 24 and 60 atoms is theoretically investigated as a function of internal energy, cluster size, and structural features. The vibrational relaxation kinetics and the associated IR emission spectra are determined by means of a Monte Carlo approach with vibrational density of states computed in the harmonic approximation. RF is generally found to be highly competitive with vibrational emission. The behaviors predicted for clusters of various sizes and archetypal structures indicate that the IR emission spectra are strongly influenced by RF, an energy gap law being obtained for the evolution of the RF rate constant depending on the electronic excitation state. The present results are relevant to the photophysics of the interstellar medium and could contribute to elucidating the carriers of the extended red emission bands and the continuum emission lying below the aromatic infrared bands believed to originate from mixed aromatic–aliphatic compounds.
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Affiliation(s)
- O. Lacinbala
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay (ISMO), 91405 Orsay, France
| | - F. Calvo
- Université Grenoble-Alpes, CNRS, LIPhy, 38000 Grenoble, France
| | - C. Dubosq
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université de Toulouse, CNRS, 31062 Toulouse, France
| | - C. Falvo
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay (ISMO), 91405 Orsay, France
- Université Grenoble-Alpes, CNRS, LIPhy, 38000 Grenoble, France
| | - P. Parneix
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay (ISMO), 91405 Orsay, France
| | - M. Rapacioli
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université de Toulouse, CNRS, 31062 Toulouse, France
| | - A. Simon
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université de Toulouse, CNRS, 31062 Toulouse, France
| | - T. Pino
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay (ISMO), 91405 Orsay, France
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3
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Mackie CJ, Candian A, Lee TJ, Tielens AGGM. Modeling the infrared cascade spectra of small PAHs: the 11.2 μm band. Theor Chem Acc 2021; 140:124. [PMID: 34720707 PMCID: PMC8549957 DOI: 10.1007/s00214-021-02807-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 07/02/2021] [Indexed: 11/18/2022]
Abstract
The profile of the 11.2 μm feature of the infrared (IR) cascade emission spectra of polycyclic aromatic hydrocarbon (PAH) molecules is investigated using a vibrational anharmonic method. Several factors are found to affect the profile including: the energy of the initially absorbed ultraviolet (UV) photon, the density of vibrational states, the anharmonic nature of the vibrational modes, the relative intensities of the vibrational modes, the rotational temperature of the molecule, and blending with nearby features. Each of these factors is explored independently and influence either the red or blue wing of the 11.2 μm feature. The majority impact solely the red wing, with the only factor altering the blue wing being the rotational temperature.
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Affiliation(s)
- Cameron J Mackie
- Kenneth S. Pitzer Center for Theoretical Chemistry Department of Chemistry, University of California, Berkeley, CA 94720 USA.,Lawrence Berkeley National Laboratory, Chemical Sciences Division, Berkeley, CA 94720 USA
| | - Alessandra Candian
- van 't Hoff Institute for Molecular Science, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands
| | - Timothy J Lee
- NASA Ames Research Center, Moffett Field, CA 94035-1000 USA
| | - Alexander G G M Tielens
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands.,Astronomy Department, University of Maryland, College Park, MD 20742 USA
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Zhang X, Peng Z, Li P, Mao Y, Shen R, Tao R, Diao X, Liu L, Zhao Y, Luo X. Complex Internal Microstructure of Feather Follicles on Chicken Skin Promotes the Bacterial Cross-Contamination of Carcasses During the Slaughtering Process. Front Microbiol 2020; 11:571913. [PMID: 33042079 PMCID: PMC7527466 DOI: 10.3389/fmicb.2020.571913] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 08/19/2020] [Indexed: 11/29/2022] Open
Abstract
Chicken skin is considered the most susceptible to bacterial contamination during slaughter. It is rich in bushy feather follicles with complex internal structures that can absorb bacteria via cross-contamination during slaughter. Until now, the microstructural changes and local bacterial composition of feather follicles during slaughter have not been thoroughly investigated. This study used hematoxylin-eosin (HE) staining of the tissue paraffin section to investigate the structure of the feather follicles on chicken skin. In addition, the biopsy sampling method was employed for the high-throughput sequencing of 16S RNA genes to study the composition and source of bacterial contamination during slaughter. The results show that the feather follicles on chicken skin form a closed cavity structure during the slaughtering process. The volume of the irregular follicle cavity was about Ø: 200 μm × D: 1040 μm, which provides a place for the bacteria to absorb and resist the cleaning and disinfection during the slaughtering process. The composition of bacteria in the feather follicle was mainly Acinetobacter (37%), Psychrobacter (8%), Macrococcus (5%), and Comamonas (2%). The heat map obtained via the species abundance analysis of the feather follicle samples as well as the slaughter environment samples suggests that the gastrointestinal feces contaminated the feather follicles on the chicken skin mainly during the evisceration, defeathering, and chilling processes, and the last-stage chilling water also caused severe cross-contamination to the feather follicles during the chilling process.
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Affiliation(s)
- Xibin Zhang
- College of Food Science and Engineering, Shandong Agricultural University, Tai'an, China.,New Hope Liuhe Co., Ltd., Laboratory of Feed and Livestock and Poultry Products Quality & Safety Control, Ministry of Agriculture, Beijing, China
| | - Zixin Peng
- Key Laboratory of Food Safety Risk Assessment, Ministry of Health, China National Center for Food Safety Risk Assessment, Beijing, China
| | - Peng Li
- Department of Food Science and Engineering, Qingdao Agricultural University, Qingdao, China
| | - Yanwei Mao
- College of Food Science and Engineering, Shandong Agricultural University, Tai'an, China
| | - Ru Shen
- New Hope Liuhe Co., Ltd., Laboratory of Feed and Livestock and Poultry Products Quality & Safety Control, Ministry of Agriculture, Beijing, China
| | - Rui Tao
- New Hope Liuhe Co., Ltd., Laboratory of Feed and Livestock and Poultry Products Quality & Safety Control, Ministry of Agriculture, Beijing, China
| | - Xiuguo Diao
- New Hope Liuhe Co., Ltd., Laboratory of Feed and Livestock and Poultry Products Quality & Safety Control, Ministry of Agriculture, Beijing, China
| | - Longhai Liu
- New Hope Liuhe Co., Ltd., Laboratory of Feed and Livestock and Poultry Products Quality & Safety Control, Ministry of Agriculture, Beijing, China
| | - Yuzhong Zhao
- New Hope Liuhe Co., Ltd., Laboratory of Feed and Livestock and Poultry Products Quality & Safety Control, Ministry of Agriculture, Beijing, China
| | - Xin Luo
- College of Food Science and Engineering, Shandong Agricultural University, Tai'an, China
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5
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Mulas G, Falvo C, Cassam-Chenaï P, Joblin C. Anharmonic vibrational spectroscopy of polycyclic aromatic hydrocarbons (PAHs). J Chem Phys 2018; 149:144102. [PMID: 30316271 DOI: 10.1063/1.5050087] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
While powerful techniques exist to accurately account for anharmonicity in vibrational molecular spectroscopy, they are computationally very expensive and cannot be routinely employed for large species and/or at non-zero vibrational temperatures. Motivated by the study of Polycyclic Aromatic Hydrocarbon (PAH) emission in space, we developed a new code, which takes into account all modes and can describe all infrared transitions including bands becoming active due to resonances as well as overtone, combination, and difference bands. In this article, we describe the methodology that was implemented and discuss how the main difficulties were overcome, so as to keep the problem tractable. Benchmarking with high-level calculations was performed on a small molecule. We carried out specific convergence tests on two prototypical PAHs, pyrene (C16H10) and coronene (C24H12), aiming at optimising tunable parameters to achieve both acceptable accuracy and computational costs for this class of molecules. We then report the results obtained at 0 K for pyrene and coronene, comparing the calculated spectra with available experimental data. The theoretical band positions were found to be significantly improved compared to harmonic density functional theory calculations. The band intensities are in reasonable agreement with experiments, the main limitation being the accuracy of the underlying calculations of the quartic force field. This is a first step toward calculating moderately high-temperature spectra of PAHs and other similarly rigid molecules using Monte Carlo sampling.
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Affiliation(s)
- Giacomo Mulas
- IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
| | - Cyril Falvo
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, University of Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | | | - Christine Joblin
- IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 Av. du Colonel Roche, 31028 Toulouse Cedex 4, France
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Mackie CJ, Chen T, Candian A, Lee TJ, Tielens AGGM. Fully anharmonic infrared cascade spectra of polycyclic aromatic hydrocarbons. J Chem Phys 2018; 149:134302. [DOI: 10.1063/1.5038725] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Cameron J. Mackie
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
| | - Tao Chen
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
- Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, 10691 Stockholm, Sweden
| | - Alessandra Candian
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
| | - Timothy J. Lee
- NASA Ames Research Center, Moffett Field, California 94035-1000, USA
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7
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Féraud G, Pino T, Falvo C, Parneix P, Combriat T, Bréchignac P. Intramolecular Processes Revealed Using UV-Laser-Induced IR-Fluorescence: A New Perspective on the "Channel Three" of Benzene. J Phys Chem Lett 2014; 5:1083-1090. [PMID: 26274453 DOI: 10.1021/jz402697u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Radiative relaxation in the infrared (IR) is common following nonradiative electronic relaxation processes, but it is rarely measured. We present ultraviolet laser-induced infrared fluorescence (UV-LIIRF) excitation spectroscopy and dispersed UV-LIIRF spectroscopy of gas phase benzene vibronically excited around the onset of channel 3, using a homemade spectrometer. We found that the vibrational IR fluorescence yield is clearly higher when benzene is excited above the onset than when it is excited below. Significant changes in dispersed IR emission profiles resulting from excitations below and above the onset of channel 3 were also observed. These results suggest that isomerization of benzene toward fulvene occurs efficiently below the opening of channel 3 and confirm that channel 3 involves a photophysical relaxation pathway that efficiently competes with isomerization.
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Affiliation(s)
- G Féraud
- Institut des Sciences Moléculaires d'Orsay, CNRS, Univ Paris-Sud, 91405 Orsay Cedex, France
| | - T Pino
- Institut des Sciences Moléculaires d'Orsay, CNRS, Univ Paris-Sud, 91405 Orsay Cedex, France
| | - C Falvo
- Institut des Sciences Moléculaires d'Orsay, CNRS, Univ Paris-Sud, 91405 Orsay Cedex, France
| | - P Parneix
- Institut des Sciences Moléculaires d'Orsay, CNRS, Univ Paris-Sud, 91405 Orsay Cedex, France
| | - T Combriat
- Institut des Sciences Moléculaires d'Orsay, CNRS, Univ Paris-Sud, 91405 Orsay Cedex, France
| | - Ph Bréchignac
- Institut des Sciences Moléculaires d'Orsay, CNRS, Univ Paris-Sud, 91405 Orsay Cedex, France
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Falvo C, Friha H, Pino T, Dhaouadi Z, Parneix P, Calvo F, Bréchignac P. Effects of hydrogen dissociation on the infrared emission spectra of naphthalene: theoretical modeling. Phys Chem Chem Phys 2013; 15:10241-50. [DOI: 10.1039/c3cp44703k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Falvo C, Calvo F, Parneix P. Probing the spin multiplicity of gas-phase polycyclic aromatic hydrocarbons through their infrared emission spectrum: a theoretical study. J Chem Phys 2012; 137:064303. [PMID: 22897269 DOI: 10.1063/1.4739468] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The anharmonic infrared emission spectrum following an optical excitation has been calculated for a variety of polycyclic aromatic hydrocarbon molecules in their ground singlet electronic state or in their triplet state. The computational protocol relies on second-order perturbation theory and involves a quartic vibrational Hamiltonian, the vibrational quantum numbers being sampled according to a Monte Carlo procedure. In the case of neutral naphthalene, the IR spectrum obtained in the (ground) singlet state differs significantly from the spectrum in the triplet state, especially for out-of-plane CH bending modes. Although not as prominent, spectral differences in larger molecules are still observable.
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Affiliation(s)
- Cyril Falvo
- Institut des Sciences Moléculaires d'Orsay, UMR CNRS 8214, Université Paris Sud, F91405 Orsay Cedex, France.
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