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Vibrational Pooling and Constrained Equilibration on Surfaces


Boney, Evans T. D. (2014) Vibrational Pooling and Constrained Equilibration on Surfaces. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/JM2J-XX84.


In this thesis, we provide a statistical theory for the vibrational pooling and fluorescence time dependence observed in infrared laser excitation of CO on an NaCl surface. The pooling is seen in experiment and in computer simulations. In the theory, we assume a rapid equilibration of the quanta in the substrate and minimize the free energy subject to the constraint at any time t of a fixed number of vibrational quanta N(t). At low incident intensity, the distribution is limited to one- quantum exchanges with the solid and so the Debye frequency of the solid plays a key role in limiting the range of this one-quantum domain. The resulting inverted vibrational equilibrium population depends only on fundamental parameters of the oscillator (ωe and ωeχe) and the surface (ωD and T). Possible applications and relation to the Treanor gas phase treatment are discussed. Unlike the solid phase system, the gas phase system has no Debye-constraining maximum. We discuss the possible distributions for arbitrary N-conserving diatom-surface pairs, and include application to H:Si(111) as an example.

Computations are presented to describe and analyze the high levels of infrared laser-induced vibrational excitation of a monolayer of absorbed 13CO on a NaCl(100) surface. The calculations confirm that, for situations where the Debye frequency limited n domain restriction approximately holds, the vibrational state population deviates from a Boltzmann population linearly in n. Nonetheless, the full kinetic calculation is necessary to capture the result in detail.

We discuss the one-to-one relationship between N and γ and the examine the state space of the new distribution function for varied γ. We derive the Free Energy, F = NγkT − kTln(∑Pn), and effective chemical potential, μn ≈ γkT, for the vibrational pool. We also find the anti correlation of neighbor vibrations leads to an emergent correlation that appears to extend further than nearest neighbor.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:vibrational transfer, constrained equilibrium, non-Boltzmann, Treanor, energy pooling
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Marcus, Rudolph A.
Thesis Committee:
  • Heath, James R. (chair)
  • Miller, Thomas F.
  • Phillips, Robert B.
  • Marcus, Rudolph A.
Defense Date:30 September 2013
Non-Caltech Author Email:boneye (AT)
Record Number:CaltechTHESIS:09302013-141151012
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7967
Deposited By: Evans Boney
Deposited On:09 Oct 2013 16:30
Last Modified:04 Oct 2019 00:02

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