메뉴 건너뛰기




Volumn 110, Issue 3, 1999, Pages 1687-1710

Molecular-dynamics simulations of solvent effects on the C-H stretching Raman bands of cyclohexane-d11 in supercritical CO2 and liquid solvents

Author keywords

[No Author keywords available]

Indexed keywords


EID: 0001177313     PISSN: 00219606     EISSN: None     Source Type: Journal    
DOI: 10.1063/1.477816     Document Type: Article
Times cited : (42)

References (128)
  • 1
    • 85034559904 scopus 로고    scopus 로고
    • note
    • The literature of this area is quite extensive. References 2-11 are some of the more helpful reviews available.
  • 17
    • 0031358211 scopus 로고    scopus 로고
    • R. Biswas, S. Bhattacharyya, and B. Bagchi, J. Chem. Phys. 108, 4963 (1998); N. Gayahtri and B. Bagchi, ibid. 107, 10381 (1997).
    • (1997) J. Chem. Phys. , vol.107 , pp. 10381
    • Gayahtri, N.1    Bagchi, B.2
  • 39
    • 0347560717 scopus 로고
    • Thesis, Duke University
    • X. Pan, Thesis, Duke University, 1995.
    • (1995)
    • Pan, X.1
  • 47
    • 0042628868 scopus 로고    scopus 로고
    • 2 vibrational relaxation/dephasing in supercritical Ar by Zewail and co-workers [C. Lienau and A. H. Zewail, J. Phys. Chem. 100, 18629 (1996); A. Materny, C. Lienau, and A. H. Zewail, ibid. 100, 18650 (1996); Q. Liu, C. Wan, and A. H. Zewail, ibid. 100, 18666 (1996)] are not included in this discussion because the conditions employed in this work are far removed from the critical point and do not show behavior of this sort.
    • (1996) J. Phys. Chem. , vol.100 , pp. 18629
    • Lienau, C.1    Zewail, A.H.2
  • 48
    • 1542476414 scopus 로고    scopus 로고
    • 2 vibrational relaxation/dephasing in supercritical Ar by Zewail and co-workers [C. Lienau and A. H. Zewail, J. Phys. Chem. 100, 18629 (1996); A. Materny, C. Lienau, and A. H. Zewail, ibid. 100, 18650 (1996); Q. Liu, C. Wan, and A. H. Zewail, ibid. 100, 18666 (1996)] are not included in this discussion because the conditions employed in this work are far removed from the critical point and do not show behavior of this sort.
    • (1996) J. Phys. Chem. , vol.100 , pp. 18650
    • Materny, A.1    Lienau, C.2    Zewail, A.H.3
  • 49
    • 0342458008 scopus 로고    scopus 로고
    • 2 vibrational relaxation/dephasing in supercritical Ar by Zewail and co-workers [C. Lienau and A. H. Zewail, J. Phys. Chem. 100, 18629 (1996); A. Materny, C. Lienau, and A. H. Zewail, ibid. 100, 18650 (1996); Q. Liu, C. Wan, and A. H. Zewail, ibid. 100, 18666 (1996)] are not included in this discussion because the conditions employed in this work are far removed from the critical point and do not show behavior of this sort.
    • (1996) J. Phys. Chem. , vol.100 , pp. 18666
    • Liu, Q.1    Wan, C.2    Zewail, A.H.3
  • 60
    • 85034543185 scopus 로고    scopus 로고
    • note
    • In Ref. 49 Remar and MacPhail corrected two minor errors in the Schwiezer and Chandler (Ref. 52) results for the repulsive contribution 10 the linewidth of a pseudo-diatomic vibration and found that after making these corrections the predicted contribution to be too small relative to the observed linewidths. However, this result was in part due to neglect of the second term in Eq. (2.14). Inclusion of this term leads to much better agreement between the observed linewidths and those calculated based on this repulsive collision model.
  • 75
    • 85034552533 scopus 로고    scopus 로고
    • note
    • The discussion in this section is adapted from the work of Oxtoby (Refs. 4 and 73). The interested reader should consult these references for detailed derivations of the basic relationships employed here.
  • 77
    • 0004003691 scopus 로고
    • Dover, New York
    • ik is the three-component vector associated with the description of normal mode k in terms of (unweighted) atomic displacements on atom i. See, for example, E. B. Wilson, J. C. Decius, and P. C. Cross, Molecular Vibrations (Dover, New York, 1955).
    • (1955) Molecular Vibrations
    • Wilson, E.B.1    Decius, J.C.2    Cross, P.C.3
  • 79
    • 85034547512 scopus 로고    scopus 로고
    • note
    • CH, rather than Eq. (2.14) itself.
  • 80
    • 85034562641 scopus 로고    scopus 로고
    • note
    • The sorts of inductive terms that would be obtained from an analysis of ∂V/∂μ all involve products of at least the first power of μ and thus are negligible for vanishing permanent dipole moment.
  • 83
    • 85034549432 scopus 로고    scopus 로고
    • note
    • 12 in the simulations. However, based on comparisons of the results obtained using mobile and immobile solutes (Sec. IV D), the difference between the relevant correlation times these two choices of mass is expected to be only 5%-7%, which is of no consequence for the present work.
  • 84
    • 0028538483 scopus 로고
    • It is important to note that the precise location of the critical point of "the" Lennard-Jones fluid in computer simulations depends upon how the potential is truncated, and to a lesser degree on the system size. The critical point we quote here applies to an unshifted potential that is truncated at 2.5σ. For a discussion of these effects see A. Z. Panagiotopoulos, Int. J. Thermophys. 15, 1057 (1994); N. B. Wilding, Phys. Rev. E 52, 602 (1995).
    • (1994) Int. J. Thermophys. , vol.15 , pp. 1057
    • Panagiotopoulos, A.Z.1
  • 85
    • 0000366719 scopus 로고
    • It is important to note that the precise location of the critical point of "the" Lennard-Jones fluid in computer simulations depends upon how the potential is truncated, and to a lesser degree on the system size. The critical point we quote here applies to an unshifted potential that is truncated at 2.5σ. For a discussion of these effects see A. Z. Panagiotopoulos, Int. J. Thermophys. 15, 1057 (1994); N. B. Wilding, Phys. Rev. E 52, 602 (1995).
    • (1995) Phys. Rev. E , vol.52 , pp. 602
    • Wilding, N.B.1
  • 99
    • 85034535935 scopus 로고    scopus 로고
    • note
    • H(r)g(r)dV.
  • 100
    • 85034542415 scopus 로고    scopus 로고
    • note
    • Ω(t) which have little effect on the predicted spectra (see the data listed under the heading "transformed width" in Table III).
  • 101
    • 85034539815 scopus 로고    scopus 로고
    • note
    • Ω(t) and in this case the spectrum shows substantial inhomogeneous broadening. The same is not true of the lighter molecule OCS also studied by these same authors (Ref. 67).
  • 102
    • 85034530150 scopus 로고    scopus 로고
    • note
    • 2)}.
  • 103
    • 85034558086 scopus 로고    scopus 로고
    • Ph.D. Thesis. The Pennsylvania State University, Chapter 3
    • c defined by Eq. (2.8) gives too much weight to the exponential tail than is really manifest in the line shape. See S. J. V. Frankland, Ph.D. Thesis. The Pennsylvania State University, 1997, Chapter 3 for more discussion.
    • (1997)
    • Frankland, S.J.V.1
  • 104
    • 85034534518 scopus 로고    scopus 로고
    • note
    • This large difference between the axial and equatorial predictions is only apparent. It results from the near cancellation of positive and negative contributions, which when viewed individually, are seen to be nearly equal for axial and equatorial C-H modes.
  • 105
    • 85034530443 scopus 로고    scopus 로고
    • note
    • We note that this problem does not exist in the analytical approaches developed in Refs. 52 and 53 since in these cases the ground-state forces are represented via hard-sphere rather than Lennard-Jones potentials.
  • 106
    • 85034534339 scopus 로고    scopus 로고
    • note
    • A factor of 2 is what is expected for a uniform distribution of solvent molecules averaged over a hemispherical region around the H atom.
  • 107
    • 85034553746 scopus 로고    scopus 로고
    • note
    • Expecting these parameters to be transferable between solvents also assumes that the Lorenz-Berthelot combining rules are correct.
  • 108
    • 85034549557 scopus 로고    scopus 로고
    • note
    • H inay seem rather large in the case of the liquid solvents, they represent changes in interaction energies upon vibrational excitation that are 1/2 as large. In all cases the change in well depth required to fit the experimental data is less than 10%, which seems physically reasonable.
  • 109
    • 85034551083 scopus 로고    scopus 로고
    • note
    • -1, in spite of the differences in the effective potentials displayed in Fig. 8.
  • 111
    • 85034542493 scopus 로고    scopus 로고
    • note
    • However, it is possible for more than a single atom within a polyatomic solvent molecule to interact repulsively with a single solute H atom.
  • 112
    • 85034550547 scopus 로고    scopus 로고
    • note
    • -1. The main source of ambiguity with such a working definition is how to count the double peaked spikes occurring at higher densities. [Two such events are seen in Fig. 11(b).] In the present work we count such double peaks as two collisions.
  • 113
    • 85034563556 scopus 로고    scopus 로고
    • note
    • r = 1.5).
  • 114
    • 85034543273 scopus 로고    scopus 로고
    • note
    • In performing these "mode" calculations all of the same parameters and interactions were included as in the Model 1 and Model 3 calculations previously described. For example, in Model 1 calculations the contribution of a given C-H bond involved the weighted force along the bond direction [Eq. (2.14)] and in Model 3 it involved only a nondirectional interaction with the H atom.
  • 115
    • 85034538168 scopus 로고    scopus 로고
    • note
    • 2 data probably reflects a coincidental cancellation of opposing effects.
  • 119
    • 85034558562 scopus 로고    scopus 로고
    • note
    • The main reason for postulating an inhomogeneous mechanism was the observation that the widths of axial to equatorial modes display an approximately constant ratio which is nearly equal to the ratio of polarizability derivatives of these two C-H bonds. Since the present simulations reproduce these width ratios in a reasonable fashion within the context of a homogeneous broadening mechanism, the relationship to polarizability derivatives [as oppose to the ratio of their squares (Ref. 49)] must be largely coincidental.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.