PMID- 16570977
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20070731
LR  - 20060330
IS  - 1520-6106 (Print)
IS  - 1520-5207 (Linking)
VI  - 110
IP  - 13
DP  - 2006 Apr 6
TI  - Effusive molecular beam study of C2H6 dissociation on Pt(111).
PG  - 6714-20
AB  - The dissociative sticking coefficient for C2H6 on Pt(111) has been measured as a 
      function of both gas temperature (Tg) and surface temperature (Ts) using effusive 
      molecular beam and angle-integrated ambient gas dosing methods. A microcanonical 
      unimolecular rate theory (MURT) model of the reactive system is used to extract 
      transition state properties from the data as well as to compare our data directly 
      with supersonic molecular beam and thermal equilibrium sticking measurements. We 
      report for the first time the threshold energy for dissociation, E0 = 26.5 +/- 3 
      kJ mol(-1). This value is only weakly dependent on the other two parameters of 
      the model. A strong surface temperature dependence in the initial sticking 
      coefficient is observed; however, the relatively weak dependence on gas 
      temperature indicates some combination of the following (i) not all molecular 
      excitations are contributing equally to the enhancement of sticking, (ii) that 
      strong entropic effects in the dissociative transition state are leading to 
      unusually high vibrational frequencies in the transition state, and (iii) energy 
      transfer from gas-phase rovibrational modes to the surface is surprisingly 
      efficient. In other words, it appears that vibrational mode-specific behavior 
      and/or molecular rotations may play stronger roles in the dissociative adsorption 
      of C2H6 than they do for CH4. The MURT with an optimized parameter set provides 
      for a predictive understanding of the kinetics of this C-H bond activation 
      reaction, that is, it allows us to predict the dissociative sticking coefficient 
      of C2H6 on Pt(111) for any combination of Ts and Tg even if the two are not equal 
      to one another.
FAU - DeWitt, Kristy M
AU  - DeWitt KM
AD  - Department of Chemistry, University of Virginia, Charlottesville, Virginia 
      22904-4319, USA.
FAU - Valadez, Leticia
AU  - Valadez L
FAU - Abbott, Heather L
AU  - Abbott HL
FAU - Kolasinski, Kurt W
AU  - Kolasinski KW
FAU - Harrison, Ian
AU  - Harrison I
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Phys Chem B
JT  - The journal of physical chemistry. B
JID - 101157530
EDAT- 2006/03/31 09:00
MHDA- 2006/03/31 09:01
CRDT- 2006/03/31 09:00
PHST- 2006/03/31 09:00 [pubmed]
PHST- 2006/03/31 09:01 [medline]
PHST- 2006/03/31 09:00 [entrez]
AID - 10.1021/jp055684h [doi]
PST - ppublish
SO  - J Phys Chem B. 2006 Apr 6;110(13):6714-20. doi: 10.1021/jp055684h.