Computing the relative gas-phase populations of C60 and C70: Beyond the traditional ΔHf,298o scale

Zdeněk Slanina, Xiang Zhao, Noriyuki Kurita, Hitoshi Gotoh, Filip Uhlík, Jerzy M. Rudziński, Kee Hag Lee, Ludwik Adamowicz

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Computations and experiments have shown that the relative heat of formation (i.e., the heat of formation per carbon atom) of C70 is lower than of C60. Moreover, various computations suggest that this is actually a general trend among fullerene cages. The relationship is particularly important for gas-phase fullerenes. Experiments have shown that C60 is typically more populated than C70 when produced in high-temperature gas-phase synthesis. It is not immediately obvious how to reconcile those two terms, or whether the relative heats of formation and the relative populations are in conflict or in agreement. This article deals with this problem, treating it as a general task of relative stabilities of gas-phase clusters of different dimensions (i.e., nonisomeric clusters) under different types of thermodynamic equilibria. The results are then applied to C60 and C70 and point out that the conventional standard pressure of 1 atm is considerably different from actual fullerene-synthesis conditions. Apparently, we should expect considerably lower cluster pressures in carbon-arc synthesis. At 1 atm, C70 is more populated than C60, but at the conditions of a saturated carbon vapor the stability order is reversed in favor of C60 so that an agreement with experiment is obtained already within the thermodynamic treatment. The pressure effects are modeled using the MNDO, AM1, PM3, and SAM1 quantum-chemical semi-empirical methods as well as the available experimental data. The computations consistently show that, if the pressure effects are considered, C60 becomes more populated than C70. Relationships of the thermodynamic treatment to more sophisticated but impractical kinetic analysis are also discussed.

Original languageEnglish (US)
Pages (from-to)216-221
Number of pages6
JournalJournal of Molecular Graphics and Modelling
Volume19
Issue number2
DOIs
StatePublished - Apr 2001

Fingerprint

Fullerenes
heat of formation
fullerenes
Pressure effects
Carbon
Gases
Thermodynamics
pressure effects
vapor phases
synthesis
carbon arcs
thermodynamics
carbon
Experiments
high temperature gases
thermodynamic equilibrium
Vapors
vapors
trends
Atoms

Keywords

  • Gibbs function
  • Relative heats of formation
  • Relative populations of fullerenes
  • Semiempirical methods
  • Stability measures

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Atomic and Molecular Physics, and Optics

Cite this

Computing the relative gas-phase populations of C60 and C70 : Beyond the traditional ΔHf,298o scale. / Slanina, Zdeněk; Zhao, Xiang; Kurita, Noriyuki; Gotoh, Hitoshi; Uhlík, Filip; Rudziński, Jerzy M.; Lee, Kee Hag; Adamowicz, Ludwik.

In: Journal of Molecular Graphics and Modelling, Vol. 19, No. 2, 04.2001, p. 216-221.

Research output: Contribution to journalArticle

Slanina, Zdeněk ; Zhao, Xiang ; Kurita, Noriyuki ; Gotoh, Hitoshi ; Uhlík, Filip ; Rudziński, Jerzy M. ; Lee, Kee Hag ; Adamowicz, Ludwik. / Computing the relative gas-phase populations of C60 and C70 : Beyond the traditional ΔHf,298o scale. In: Journal of Molecular Graphics and Modelling. 2001 ; Vol. 19, No. 2. pp. 216-221.
@article{0e10506ff8bc44b188f77118ddf3dbcd,
title = "Computing the relative gas-phase populations of C60 and C70: Beyond the traditional ΔHf,298o scale",
abstract = "Computations and experiments have shown that the relative heat of formation (i.e., the heat of formation per carbon atom) of C70 is lower than of C60. Moreover, various computations suggest that this is actually a general trend among fullerene cages. The relationship is particularly important for gas-phase fullerenes. Experiments have shown that C60 is typically more populated than C70 when produced in high-temperature gas-phase synthesis. It is not immediately obvious how to reconcile those two terms, or whether the relative heats of formation and the relative populations are in conflict or in agreement. This article deals with this problem, treating it as a general task of relative stabilities of gas-phase clusters of different dimensions (i.e., nonisomeric clusters) under different types of thermodynamic equilibria. The results are then applied to C60 and C70 and point out that the conventional standard pressure of 1 atm is considerably different from actual fullerene-synthesis conditions. Apparently, we should expect considerably lower cluster pressures in carbon-arc synthesis. At 1 atm, C70 is more populated than C60, but at the conditions of a saturated carbon vapor the stability order is reversed in favor of C60 so that an agreement with experiment is obtained already within the thermodynamic treatment. The pressure effects are modeled using the MNDO, AM1, PM3, and SAM1 quantum-chemical semi-empirical methods as well as the available experimental data. The computations consistently show that, if the pressure effects are considered, C60 becomes more populated than C70. Relationships of the thermodynamic treatment to more sophisticated but impractical kinetic analysis are also discussed.",
keywords = "Gibbs function, Relative heats of formation, Relative populations of fullerenes, Semiempirical methods, Stability measures",
author = "Zdeněk Slanina and Xiang Zhao and Noriyuki Kurita and Hitoshi Gotoh and Filip Uhl{\'i}k and Rudziński, {Jerzy M.} and Lee, {Kee Hag} and Ludwik Adamowicz",
year = "2001",
month = "4",
doi = "10.1016/S1093-3263(00)00113-3",
language = "English (US)",
volume = "19",
pages = "216--221",
journal = "Journal of Molecular Graphics and Modelling",
issn = "1093-3263",
publisher = "Elsevier Inc.",
number = "2",

}

TY - JOUR

T1 - Computing the relative gas-phase populations of C60 and C70

T2 - Beyond the traditional ΔHf,298o scale

AU - Slanina, Zdeněk

AU - Zhao, Xiang

AU - Kurita, Noriyuki

AU - Gotoh, Hitoshi

AU - Uhlík, Filip

AU - Rudziński, Jerzy M.

AU - Lee, Kee Hag

AU - Adamowicz, Ludwik

PY - 2001/4

Y1 - 2001/4

N2 - Computations and experiments have shown that the relative heat of formation (i.e., the heat of formation per carbon atom) of C70 is lower than of C60. Moreover, various computations suggest that this is actually a general trend among fullerene cages. The relationship is particularly important for gas-phase fullerenes. Experiments have shown that C60 is typically more populated than C70 when produced in high-temperature gas-phase synthesis. It is not immediately obvious how to reconcile those two terms, or whether the relative heats of formation and the relative populations are in conflict or in agreement. This article deals with this problem, treating it as a general task of relative stabilities of gas-phase clusters of different dimensions (i.e., nonisomeric clusters) under different types of thermodynamic equilibria. The results are then applied to C60 and C70 and point out that the conventional standard pressure of 1 atm is considerably different from actual fullerene-synthesis conditions. Apparently, we should expect considerably lower cluster pressures in carbon-arc synthesis. At 1 atm, C70 is more populated than C60, but at the conditions of a saturated carbon vapor the stability order is reversed in favor of C60 so that an agreement with experiment is obtained already within the thermodynamic treatment. The pressure effects are modeled using the MNDO, AM1, PM3, and SAM1 quantum-chemical semi-empirical methods as well as the available experimental data. The computations consistently show that, if the pressure effects are considered, C60 becomes more populated than C70. Relationships of the thermodynamic treatment to more sophisticated but impractical kinetic analysis are also discussed.

AB - Computations and experiments have shown that the relative heat of formation (i.e., the heat of formation per carbon atom) of C70 is lower than of C60. Moreover, various computations suggest that this is actually a general trend among fullerene cages. The relationship is particularly important for gas-phase fullerenes. Experiments have shown that C60 is typically more populated than C70 when produced in high-temperature gas-phase synthesis. It is not immediately obvious how to reconcile those two terms, or whether the relative heats of formation and the relative populations are in conflict or in agreement. This article deals with this problem, treating it as a general task of relative stabilities of gas-phase clusters of different dimensions (i.e., nonisomeric clusters) under different types of thermodynamic equilibria. The results are then applied to C60 and C70 and point out that the conventional standard pressure of 1 atm is considerably different from actual fullerene-synthesis conditions. Apparently, we should expect considerably lower cluster pressures in carbon-arc synthesis. At 1 atm, C70 is more populated than C60, but at the conditions of a saturated carbon vapor the stability order is reversed in favor of C60 so that an agreement with experiment is obtained already within the thermodynamic treatment. The pressure effects are modeled using the MNDO, AM1, PM3, and SAM1 quantum-chemical semi-empirical methods as well as the available experimental data. The computations consistently show that, if the pressure effects are considered, C60 becomes more populated than C70. Relationships of the thermodynamic treatment to more sophisticated but impractical kinetic analysis are also discussed.

KW - Gibbs function

KW - Relative heats of formation

KW - Relative populations of fullerenes

KW - Semiempirical methods

KW - Stability measures

UR - http://www.scopus.com/inward/record.url?scp=0035020745&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035020745&partnerID=8YFLogxK

U2 - 10.1016/S1093-3263(00)00113-3

DO - 10.1016/S1093-3263(00)00113-3

M3 - Article

C2 - 11391872

AN - SCOPUS:0035020745

VL - 19

SP - 216

EP - 221

JO - Journal of Molecular Graphics and Modelling

JF - Journal of Molecular Graphics and Modelling

SN - 1093-3263

IS - 2

ER -