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Zhao XM, Wei YK, Zhang K, Zhao ZW, Wang S, Miao W, Du SX, Zhang SJ, Li WF, Guan CL, Shi LP, Lu XP, Xu SK. Temperature effect on vibrational properties of crystalline Dibenz[a,h]anthracene. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 274:121107. [PMID: 35259706 DOI: 10.1016/j.saa.2022.121107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/28/2022] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
Vibrational properties associated with the intra- and intermolecular bonding of the crystalline Dibenz[a,h]anthracene at low temperatures are investigated by Raman scattering. A complete characterization of phonon spectra is given for this material. In the 120-150 K temperature region, several lattice modes show abrupt changes of splitting and the discontinuities in the temperature shift, but no emergence of new modes. Moreover, the intensity ratio of I68/38 is greater than 1 below 130 K. Meanwhile, the aromatic C-C stretching modes exhibit anomalous behaviors in frequencies, widths, and intensities at about 130 K. These spectroscopic results demonstrate a disorder-order transition occurred at about 130 K. However, the modes, corresponding to C-H out-of-plane bending, C-H in-plane bending, and/or C-H rocking, have no significant change in the whole temperature range. It indicates that the transition mainly results from the change of the tilt angle between the molecules. Our work is of great significance to understand the internal vibrational properties of Dibenz[a,h]anthracene, and it also provides considerable supports for the further study of this material.
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Affiliation(s)
- Xiao-Miao Zhao
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China; Henan Province Engineering Research Center of New Cermet Matrix Composites, Zhengzhou 450001, China.
| | - Yong-Kai Wei
- College of Science, Henan University of Technology, Zhengzhou 450001, China
| | - Kai Zhang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China; Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
| | - Zhi-Wei Zhao
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China; Henan Province Engineering Research Center of New Cermet Matrix Composites, Zhengzhou 450001, China.
| | - Shun Wang
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Wei Miao
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Su-Xuan Du
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Shi-Jie Zhang
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Wen-Feng Li
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Chun-Long Guan
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Li-Ping Shi
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin 150001, China
| | - Xin-Po Lu
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - San-Kui Xu
- College of Materials Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
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2
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Bertoldo Menezes D, Reyer A, Benisek A, Dachs E, Pruner C, Musso M. Raman spectroscopic insights into the glass transition of poly(methyl methacrylate). Phys Chem Chem Phys 2021; 23:1649-1665. [PMID: 33411861 DOI: 10.1039/d0cp05627h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Poly(methyl methacrylate) (PMMA) is a very versatile polymer which is used as a glass substitute or as an economical alternative to polycarbonate for many types of important applications, due to its particular physical properties. In this study we deal with the Raman spectroscopic characterization of the glass transition of PMMA, the value of the glass transition temperature being generally a decisive parameter for determining the application of polymers. The information obtained by two-dimensional correlation spectroscopy (2DCOS) analysis and perturbation-correlation moving-windows spectroscopy (PCMW2D) analysis of the temperature dependent depolarized Raman spectra enabled us to recognize that the glass transition of PMMA is ruled by intermolecular interactions which influence the vibrational modes of the molecular groups associated with ν(C[double bond, length as m-dash]O), δa(C-H) of α-CH3 and/or O-CH3, ν(C-O-C), ν(C-COO), and ν(C-C-O). This information was employed for the temperature dependent study of the Raman shift and of the full width at half maximum of the Raman peaks obtained through anisotropic and isotropic Raman spectra, of the depolarization ratio, of the Raman spectroscopic noncoincidence effect, and of the Raman peak intensities represented by Arrhenius-type plots, all results supporting the outcomes of this work. The comparison with results obtained by differential scanning calorimetry and with published results in molecular dynamics studies was also part of this work. As the main result, one can highlight the peak associated with the ν(C-O-C) stretching mode at around 812 cm-1 as the one which presents the better outcome for explaining the glass transition from the molecular point of view.
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Affiliation(s)
- D Bertoldo Menezes
- Federal Institute of Triângulo Mineiro, 1020, 38400-970, Uberlândia, Minas Gerais, Brazil. and Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020, Salzburg, Austria
| | - A Reyer
- Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020, Salzburg, Austria
| | - A Benisek
- Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020, Salzburg, Austria
| | - E Dachs
- Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020, Salzburg, Austria
| | - C Pruner
- Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020, Salzburg, Austria
| | - M Musso
- Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020, Salzburg, Austria
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Hestand NJ, Strong SE, Shi L, Skinner JL. Mid-IR spectroscopy of supercritical water: From dilute gas to dense fluid. J Chem Phys 2019; 150:054505. [DOI: 10.1063/1.5079232] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Nicholas J. Hestand
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Steven E. Strong
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Liang Shi
- School of Natural Sciences, University of California, Merced, California 95344, USA
| | - J. L. Skinner
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
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Hetmańczyk J, Nowicka-Scheibe J, Maurin JK, Pawlukojć A. Low temperature investigations of dynamic properties in l-leucine - chloranilic acid complex. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 200:281-289. [PMID: 29702418 DOI: 10.1016/j.saa.2018.03.070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 03/20/2018] [Accepted: 03/25/2018] [Indexed: 06/08/2023]
Abstract
Inelastic neutron scattering (INS) and infra-red (IR) spectroscopy methods were used for determination of dynamic structure of l-leucine - chloranilic acid complex. A theoretical dynamic pattern calculated by the density functional theory (DFT) method for periodic boundary conditions accompanied the experimental ones. Normal modes in the vibrational spectra were defined and described. The characteristic presence of the Hadži's trio enriched by numerous submaxima is observed in the wavenumber range 3200-800 cm-1. Bands assigned to CH3 torsion vibrations in the leucine cation were observed at 231 cm-1 and 258 cm-1 in the INS spectrum. Temperature-dependent far-infrared spectra in the temperature range 9 K-290 K were obtained. Vibrational bands were analyzed as a function of temperature. Activation energies for reorientational motion of CH3 and CH2 groups were determined by means of the band shape analysis performed for torsional and twisting vibrations of these groups. The estimated energy is equal to Ea = 2.7 ± 0.2 kJ/mol and Ea = 2.17 ± 0.12 kJ/mol for CH3 and CH2 groups, respectively. A phase transition at about 130 K in the l-leucine - chloranilic acid complex was observed.
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Affiliation(s)
- J Hetmańczyk
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2 str., 30-387 Cracow, Poland
| | - J Nowicka-Scheibe
- Faculty of Chemical Technology and Engineering, Institute of Chemistry and Environmental Protection, West Pomeranian University of Technology, Al. Piastów 42, 71-065 Szczecin, Poland
| | - J K Maurin
- National Medicines Institute, Chełmska 30/34 str., 00-725 Warsaw, Poland; National Centre for Nuclear Research, Sołtana 7, 05-400 Otwock, Poland
| | - A Pawlukojć
- Institute of Nuclear Chemistry and Technology, Dorodna 16 str., 03-195 Warszawa, Poland; Joint Institute for Nuclear Research, 141-980 Dubna, Russia.
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Samanta T, Dutta R, Biswas R, Bagchi B. Infrared spectroscopic study of super-critical water across the Widom line. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2018.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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6
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Bertoldo Menezes D, Reyer A, Musso M. Investigation of the Brill transition in nylon 6,6 by Raman, THz-Raman, and two-dimensional correlation spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 190:433-441. [PMID: 28961527 DOI: 10.1016/j.saa.2017.09.055] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/19/2017] [Accepted: 09/19/2017] [Indexed: 06/07/2023]
Abstract
The Brill transition is a phase transition process in polyamides related with structural changes between the hydrogen bonds of the lateral functional groups (CO) and (NH). In this study, we have used the potential of Raman spectroscopy for exploring this phase transition in polyamide 6,6 (nylon 6,6), due to the sensitivity of this spectroscopic technique to small intermolecular changes affecting vibrational properties of relevant functional groups. During a step by step heating and cooling process of the sample we collected Raman spectra allowing us from two-dimensional Raman correlation spectroscopy to identify which spectral regions suffered the largest influence during the Brill transition, and from Terahertz Stokes and anti-Stokes Raman spectroscopy to obtain complementary information, e.g. on the temperature of the sample. This allowed us to grasp signatures of the Brill transition from peak parameters of vibrational modes associated with (CC) skeletal stretches and (CNH) bending, and to verify the Brill transition temperature at around 160°C, as well as the reversibility of this phase transition.
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Affiliation(s)
- D Bertoldo Menezes
- Federal Institute of the Triângulo Mineiro, Mailbox: 1020, Zip Code 38400-970, Uberlândia, Minas Gerais, Brazil; Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020 Salzburg, Austria.
| | - A Reyer
- Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020 Salzburg, Austria
| | - M Musso
- Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, 5020 Salzburg, Austria
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7
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Bertoldo Menezes D, Reyer A, Marletta A, Musso M. Determination of the temperatures of the γ, β and α relaxation processes in nylon 6,6 by Raman spectroscopy. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.10.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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8
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Chaikina YA. Local random structure of supercritical carbon dioxide. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2015. [DOI: 10.1134/s1990793114080041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Kramberger C, Thurakitseree T, Einarsson E, Takashima A, Kinoshita T, Muro T, Maruyama S. From isotope labeled CH₃CN to N₂ inside single-walled carbon nanotubes. NANOSCALE 2014; 6:1525-1528. [PMID: 24322271 DOI: 10.1039/c3nr04729f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The observation of one-dimensional N₂ inside single-walled carbon nanotubes raises the questions, how are the N₂ molecules formed and how do they manage to make their way to this peculiar place? We have used N(15) and C(13) isotope labeled acetonitrile during the synthesis of single-walled carbon nanotubes to investigate this process. The isotope shifts of phonons and vibrons are observed by Raman spectroscopy and X-ray absorption. We identify the catalytic decomposition of acetonitrile as the initial step in the reaction pathway to single-walled carbon nanotubes containing encapsulated N₂.
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Suzuki H, Matsuzaki Y, Muraoka A, Tachikawa M. Raman spectroscopy of optically levitated supercooled water droplet. J Chem Phys 2012; 136:234508. [DOI: 10.1063/1.4729476] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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11
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Tassaing T, Soetens JC, Vyalov I, Kiselev M, Idrissi A. Supercritical ammonia: A molecular dynamics simulation and vibrational spectroscopic investigation. J Chem Phys 2010; 133:214505. [PMID: 21142306 DOI: 10.1063/1.3506868] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- T Tassaing
- Institut des Sciences Moléculaires, Université Bordeaux 1, UMR-CNRS 5255, 351 cours de la Libération, 33405 Talence Cedex, France
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12
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Kajiya D, Saitow KI. Site-Selective Solvation in Supercritical CO2Observed by Raman Spectroscopy: Phenyl Group Leads to Greater Attractive Energy than Chloro Group. J Phys Chem B 2010; 114:16832-7. [DOI: 10.1021/jp107820j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Daisuke Kajiya
- Natural Science Center for Basic Research and Development (N-BARD) and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
| | - Ken-ichi Saitow
- Natural Science Center for Basic Research and Development (N-BARD) and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
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13
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Idrissi A, Vyalov I, Damay P, Frolov A, Oparin R, Kiselev M. Assessment of the Spatial Distribution in Sub- and Supercritical CO2 Using the Nearest Neighbor Approach: A Molecular Dynamics Analysis. J Phys Chem B 2009; 113:15820-30. [DOI: 10.1021/jp9042107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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14
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15
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Kajiya D, Mouri Y, Saitow KI. Difference of Solute−Solvent Interactions of cis- and trans-1,2-Dichloroethylene in Supercritical CO2 Investigated by Raman Spectroscopy. J Phys Chem B 2008; 112:7980-3. [DOI: 10.1021/jp803875x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Daisuke Kajiya
- Natural Science Center for Basic Research and Development (N-BARD), Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, and PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Yutaka Mouri
- Natural Science Center for Basic Research and Development (N-BARD), Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, and PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Ken-ichi Saitow
- Natural Science Center for Basic Research and Development (N-BARD), Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, and PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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16
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Vibrational and rotational relaxation of hexafluorobenzene studied by Raman scattering in the supercritical domain. J Mol Liq 2006. [DOI: 10.1016/j.molliq.2005.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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17
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Saitow KI, Sasaki J. Attractive and repulsive interactions among methanol molecules in supercritical state investigated by Raman spectroscopy and perturbed hard-sphere theory. J Chem Phys 2005; 122:104502. [PMID: 15836327 DOI: 10.1063/1.1858442] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The short-range structure of supercritical methanol (CH(3)OH) is investigated by measuring the spontaneous Raman spectra of the C-O stretching mode. The spectra are obtained at a reduced temperature, T(r)=T/T(c)=1.02 (522.9 K), which permits the neat fluid to be studied isothermally as a function of density. As the density increases, the spectral peaks shift toward the lower energy side and the spectra broaden. In the supercritical region, the amount of shifting shows nonlinear density dependence and the width becomes anomalously large. We use the perturbed hard-sphere model to analyze these density dependencies along the vibrational coordinate. The amount of shifting is decomposed into attractive and repulsive components, and the changes in attractive and repulsive energies are evaluated as functions of density and packing fraction, both of which are continuously varied by a factor of 120. Here we show that the shift amount consists principally of the attractive component at all densities, since the attractive energy is about eight times the repulsive energy. The density dependence of the widths is analyzed by calculating homogeneous and inhomogeneous widths as a function of density. The results show that, although vibrational dephasing and density inhomogeneity contribute similarly to the width at low and middle densities, at high density the main contributor turns out to be the vibrational dephasing. We estimate the local density enhancements of supercritical CH(3)OH as function of bulk density by two methods. The results of these analyses show common features, and both the estimated local density enhancements of CH(3)OH are considerably larger than the local density enhancements of simple fluids, i.e., those having nonhydrogen bonding. It is revealed that the local density of supercritical CH(3)OH is 40%-60% greater than the local densities of the simple fluids. We also estimate the local density fluctuation using the obtained values of attractive shift, inhomogeneous width, and local density. The density fluctuation in the vicinity of a vibrating molecule is compared to the fluctuation of bulk density, which is obtained from the thermodynamic calculation.
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Affiliation(s)
- Ken-ichi Saitow
- Department of Physics, Faculty of Science, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan.
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18
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Egorov SA, Lawrence CP, Skinner JL. A Mode-Coupling Theory of Vibrational Line Broadening in Near-Critical Fluids. J Phys Chem B 2005; 109:6879-83. [PMID: 16851774 DOI: 10.1021/jp0449861] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We present a fully microscopic mode-coupling theory of near-critical line broadening. All the structural and dynamical input required by the theory is calculated directly from intermolecular potentials. We compute vibrational frequency time-correlation functions and line shapes as the critical point is approached along both the critical isochore and the liquid-gas coexistence curve. Theory is shown to be in good agreement with simulation.
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Affiliation(s)
- S A Egorov
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
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19
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Sugimoto K, Fujiwara H, Koda S. Raman spectroscopic study on the local structure around O2 in supercritical water. J Supercrit Fluids 2004. [DOI: 10.1016/j.supflu.2003.12.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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20
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Saitow KI, Nakayama H, Ishii K, Nishikawa K. Attractive and Repulsive Intermolecular Interactions of a Polar Molecule: Short-Range Structure of Neat Supercritical CHF3 Investigated by Raman Spectroscopy. J Phys Chem A 2004. [DOI: 10.1021/jp049225c] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Ken-ichi Saitow
- Department of Physics, Faculty of Science, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan
| | - Hideyuki Nakayama
- Department of Chemistry, Faculty of Science, Gakushuin University, Mejiro, Toshima, Tokyo 171-8588, Japan
| | - Kikujiro Ishii
- Department of Chemistry, Faculty of Science, Gakushuin University, Mejiro, Toshima, Tokyo 171-8588, Japan
| | - Keiko Nishikawa
- Division of Diversity Science, Graduate School of Science and Technology, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan
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Lawrence CP, Skinner JL. On the mode-coupling theory of vibrational line broadening in near-critical fluids. J Chem Phys 2004; 120:8651-61. [PMID: 15267794 DOI: 10.1063/1.1689954] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular-dynamics simulations of a neat atomic fluid, coupled with a simple model for vibrational frequency perturbations, are used to investigate vibrational line broadening near the liquid-gas critical point. All features of our simulations are in qualitative agreement with recent Raman experiments on nitrogen. We also use our simulation results to assess the validity of the mode-coupling theories that have been used to analyze experiment. We find that the theoretical results are not in good agreement with simulation, both for the temperature dependence of the linewidth, and for the frequency time-correlation functions. However, the mode-coupling prediction that critical line broadening is due to the diverging correlation time of the frequency fluctuations is shown to be correct.
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Affiliation(s)
- C P Lawrence
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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22
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Everitt KF, Lawrence CP, Skinner JL. Density-Dependent Isotropic Raman Line Shapes in Compressed Room-Temperature Nitrogen. J Phys Chem B 2004. [DOI: 10.1021/jp0379446] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- K. F. Everitt
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - C. P. Lawrence
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - J. L. Skinner
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
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23
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Roychowdhury S, Bagchi B. Simulation and theory of vibrational phase relaxation in the critical and supercritical nitrogen: Origin of observed anomalies. J Chem Phys 2003. [DOI: 10.1063/1.1587699] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Roychowdhury S, Bagchi B. Vibrational phase relaxation along the critical isochore of nitrogen: the role of local density fluctuations in the rate enhancement. PHYSICAL REVIEW LETTERS 2003; 90:075701. [PMID: 12633246 DOI: 10.1103/physrevlett.90.075701] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2002] [Indexed: 05/24/2023]
Abstract
Vibrational dephasing of the nitrogen molecule is known to show highly interesting anomalies near its gas-liquid critical point. Here we present theoretical and computational studies of the Raman linewidth of nitrogen along the critical isochore. The linewidth is found to have a lambda-shaped temperature dependence near the critical point. As observed in experimental studies, the calculated line shape becomes Gaussian as the critical temperature (T(c)) is approached. Both the present simulation and a mode coupling theory analysis show that the slow decay of the enhanced density fluctuations near the critical point, probed at the subpicosecond time scales by vibrational frequency modulation, along with an enhanced vibration-rotation coupling, are the main causes of the observed anomalies.
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Affiliation(s)
- Swapan Roychowdhury
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560012, India
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25
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Saitow KI, Otake K, Nakayama H, Ishii K, Nishikawa K. Local density enhancement in neat supercritical fluid due to attractive intermolecular interactions. Chem Phys Lett 2003. [DOI: 10.1016/s0009-2614(02)01851-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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