A molecular beam study of D2 dissociation on Pt(1 1 1): Testing SRP-DFT calculations

Assessment of Two Problems of Specific Reaction Parameter Density Functional Theory: Sticking and Diffraction of H2 on Pt(111)

“…Finally, sticking probabilities of D 2 on Pt(111) were published by Cao et al, 17 in the framework of a comparison to previously published S 0 computed on the basis of SRP-DFT. 9 We focus on the sticking probabilities S 0 , reported in Figure 1, of their paper, 17 which were measured at T s = 200 K. The sticking probabilities were measured with the King and Wells technique. 33 The beam energies were varied by both changing T n (temperatures up to 1520 K were used) and by seeding D 2 in H 2 or in Ne, N 2 , or Ar.…”

“…In turn, the Boltzmann-averaged reaction probability can be computed from the initial (ν, j ) state selected reaction probability P deg ( E , ν, j ) according towithandHere, ν is the vibrational and j is the rotational quantum number of D 2 and W ( j ) is 2 for even j and 1 for odd j . For the rotational temperature, typically T rot = 0.8 T n is assumed, 39,40 based mostly on experiments by Gallagher and Fenn, 41 and this is what we used to simulate the experiments of Luntz et al 15 and of Cao et al 17 The assumption made by Hodgson and co-workers that E i = 2.75 k B T n corresponds to T rot = 0.75 T n , and this was used to simulate their experiments. 16 The beam parameters of Groot et al describe molecular beams that are comparatively broad in energy (with large α parameters), as can be seen from Figure 1 of ref (37).…”

“…Comparison of the energy dependence of the sticking probability of D 2 on Pt(111) for three different sets of experimental data from Hodgson and co. 16 (red circles), Luntz et al 15 (black circles for a surface temperature, T s , of 293 K, green circles for T s ≈ 150 K), and Cao et al 17 (blue circles). Nozzle temperatures T n are indicated (in K) for the experiments of Hodgson and co-workers and of Cao et al…”

Chiral Surface Characterisation and Reactivity Toward H–D Exchange of a Curved Platinum Crystal

“…S 0 (D 2 ) has been shown to be nearly temperature independent between 100 and 350 K for Pt(111) and vicinal surfaces. [51][52][53][54][55] We therefore expect no appreciable differences between the surface structures found in the STM study at room temperature, and during the molecular beam study at 155 K. Figure 3 shows in the bottom half of the graph the absolute dissociation probabilities of D 2 versus step density. The grey shaded areas indicate the part of the curved crystal that has a reduced width due to tapering of the crystal's edges.…”

“…First, for the kinetic energy used here, there is also no significant temperature dependence to reactivity. This is important as we will compare the dependence in dissociation measured at 300 K to the H-D exchange at 500 K. Second, none of the supersonic molecular beam studies of hydrogen dissociation on Pt(111) and stepped Pt surfaces has ever reported an isotope effect, while all surfaces show a slightly different kinetic energy dependence [51][52][53][54][55]58]. As we use a single beam containing both H 2 and D 2 , their velocities are (nearly) identical.…”