A vibrational spectroscopy study on the interaction of N2 with clean and K-promoted Fe(111) surfaces: π-bonded dinitrogen as precursor for dissociation

Tsai, M.-C.; Seip, U.; Bassignana, I.C.; Küppers, J.; Ertl, G.

doi:10.1016/0039-6028(85)90005-6

Cited by 119 publications

(35 citation statements)

References 24 publications

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“…The adsorption energy is E ads ≈ 0.64 eV and the molecular center of mass is located at Z = 1.2 Å, on the hollow site and with an internuclear distance increased by about 0.1 Å (r = 1.2 Å). The α-state is well known experimentally [26][27][28][29][30][31][32] and theoretically, 34,51 with an adsorption energy larger than the one of the γstate by about 200 meV. 26,27,31,32 In our calculations, we find the same energy difference.…”

Section: Static Adsorption Statessupporting

confidence: 77%

“…Figure 6 illustrates the interaction between the N 2 molecule and the Fe(111) surface as a function of the molecule-surface distance Z. The reference energy is taken to be that of the N 2 molecule detected experimentally in all the previous studies, [26][27][28][29][30][31][32] as well as predicted theoretically, 34,51 with an adsorption energy ranging between 0.2 and 0.4 eV. 26,27,31,32 The molecular nitrogen adsorption into the δ-state (dark-grey symbols) is characterized by an adsorption energy of E ads ≈ 0.45 eV, slightly weaker than the γ-state and with molecular center of mass distance to the surface of Z ≈ 1.7 Å.…”

Section: Static Adsorption Statesmentioning

confidence: 99%

“…A similar conclusion was derived from previous experimental studies. [28][29][30][31] Figure 11 shows the variation of the N 2 /Fe(111) relative adsorption probability into top, hcp, fcc and hollow sites of the unit cell, corresponding to the possible adsorption states γ, δ, α, and ε, respectively, with the initial molecular incidence energy at T s = 300 K. At very low energy, in agreement with experimental observations, 26,27 adsorption into the γ-state has a relative adsorption probability close to one (σ γ ≈ 1). Adsorption into the α-state has a relative adsorption probability σ α ≈ 10 −2 for the same range of energies.…”

Section: Incidence Energy E I (Ev)mentioning

confidence: 99%

“…[26][27][28][29][30][31][32][33] For a wide range of substrate temperatures and for thermal energies of the incoming N 2 molecules, two molecular adsorption states have been identified, namely, a weakly bound state γ-N 2 , with the molecular axis perpendicular to the surface plane, and a more strongly bound adsorption state α-N 2 , with the molecule adsorbed on the hollow site, parallel to the surface plane, and with stretched internuclear distance. [26][27][28][29][30][31][32][33] At low surface temperatures and when the surface is already saturated with γ-N 2 , an additional adsorption state, δ-N 2 , has been experimentally observed with the molecule on top of a second layer atom and perpendicular to the surface. 32 Furthermore, a fourth adsorption state (εstate) was reported in Ref.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption dynamics of molecular nitrogen at an Fe(111) surface

Nosir

Martin-Gondre

Bocan

et al. 2017

Phys. Chem. Chem. Phys.

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We present an extensive theoretical study of N adsorption mechanisms on an Fe(111) surface. We combine the static analysis of a six-dimensional potential energy surface (6D-PES), based on ab initio density functional theory (DFT) calculations for the system, with quasi-classical trajectory (QCT) calculations to simulate the adsorption dynamics. There are four molecular adsorption states, usually called γ, δ, α, and ε, arising from our DFT calculations. We find that N adsorption in the γ-state is non-activated, while the threshold energy is associated with the entrance channel for the other three adsorption states. Our QCT calculations confirm that there are activated and nonactivated paths for the adsorption of N on the Fe(111) surface, which is in agreement with previous experimental investigations. Molecular dynamics at a surface temperature T = 300 K and impact energies E in the 0-5 eV range show the relative occupancy of the γ, δ, α, and ε states. The δ-state, however, is only marginally populated despite its adsorption energy being very similar to that of the γ-state. Our QCT calculations trace the dependence of molecular trapping on the surface temperature T and initial impact energy E and quantify the rates of the different competitive channels that eventually lead to molecular adsorption.

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Section: Static Adsorption Statessupporting

confidence: 77%

Section: Static Adsorption Statesmentioning

confidence: 99%

Section: Incidence Energy E I (Ev)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Adsorption dynamics of molecular nitrogen at an Fe(111) surface

Nosir

Martin-Gondre

Bocan

et al. 2017

Phys. Chem. Chem. Phys.

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“…Grunze et al confirmed these findings and suggested that the nitrogen dissociation proceeds via a precursor state. 24 All subsequent experimental observations [25][26][27][28][29] reached similar conclusions. Overtime, other molecular adsorption states were reported as well: Grunze et al found a rarely occupied adsorption δ-state, 29 and Freund and coworkers observed an additional molecular adsorption ε-state.…”

Section: Introductionsupporting

confidence: 69%

Dissociative adsorption dynamics of nitrogen on a Fe(111) surface

Nosir

Martin-Gondre

Bocan

et al. 2017

Phys. Chem. Chem. Phys.

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We study the dissociative adsorption dynamics of N on clean bcc Fe(111) surfaces. We base our theoretical analysis on a multidimensional potential energy surface built from density functional theory. The dissociative sticking probability is computed by means of quasi-classical trajectory calculations. For normal incidence and impact energies of the order of a few eV, our theoretical results agree well with existing experimental values. For these energies, the dynamics of the dissociated molecules shows that dissociation is a direct process that follows narrow paths in the multidimensional space. For lower energies of the beam, this direct process is not enough to explain the measured values. A better agreement with the experiment is obtained if we increase the surface temperature to promote the transfer to dissociation of molecules previously trapped. Most of the molecules dissociate very close to the Fe(111) third layer atoms and with an orientation parallel to the surface. A comparison between the dissociation of N on Fe(111) and Fe(110) highlights the role of the different energy barriers in both surfaces.

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