Dipole–dipole interactions among CH3Cl molecules on Ru(001): Correlation between work function change and thermal desorption studies

Abstract

Articles you may be interested inReversible work function changes induced by photoisomerization of asymmetric azobenzene dithiol selfassembled monolayers on gold Appl. Phys. Lett. 93, 083109 (2008); 10.1063/1.2969468 First-principles theoretical study of Al q 3 ∕ Al interfaces: Origin of the interfacial dipole Coordination and reaction mechanism of furan on Ru(001) J. Chem. Phys. 111, 8068 (1999); 10.1063/1.480140Long-range, collision-induced dipoles of T d -D ∞h molecule pairs: Theory and numerical results for CH 4 or CF 4 interacting with H 2 , N 2 , CO 2 , or CS 2 Work function change measurements ͑⌬⌽͒ combined with temperature programmed desorption ͑TPD͒ were employed to study layer growth mechanism and the CH 3 Cl dipole-dipole interactions on Ru͑001͒, over the temperature range of 97 K-230 K. The activation energy for desorption (E a ) and the molecular dipole moment ͑͒ both decrease from 55.9 kJ/mol and 2.44 D, at the zero coverage limit, to 38.6 kJ/mol and 1.27 D, at one monolayer. This coverage dependence originates from strong dipolar lateral repulsion among neighbor CH 3 Cl molecules. Using a model introduced by Maschhoff and Cowin ͑MC͒ ͓J. Chem. Phys. 101, 8138 ͑1994͔͒, the isolated adsorbed molecule's dipole moment, 0 ͑2.35 D͒ and polarizability ␣(8.1ϫ10 Ϫ24 cm 3 ), were extracted from TPD data. These values agree very well with 0 ͑2.12 D͒ and ␣(9.2ϫ10 Ϫ24 cm 3 ) obtained from work function change measurements by employing the same MC model. The ability to simulate both TPD and work function change data over a wide coverage range within the framework of a single electrostatic model has been demonstrated. It enabled better understanding of fine details of surface dipolar interactions.

Adsorption geometry of ethyl iodide on clean and oxygen covered Ru(001) surfaces: LEIS, XPS and TDS study

“…Molecules of the second layer would also adsorb in the middle of those of the first layer, in this picture. Similar bilayer model was concluded for CH 3 Br [19] and CH 3 Cl [20] on Ru(001) and for C 2 H 5 Cl [21] on Pt(111).…”

Electron-induced chemistry of methyl chloride caged within amorphous solid water

“…The number of methyl chloride molecules 56 reported per adsorbed monolayer on Ru(0001) is between 4.6 ± 0.3 × 10 14 molecules/cm 2 down to 3.6 × 10 14 molecules/ cm 2 according to former work based on Kelvin probe experiments. 57 Therefore, in our apparatus (the crystal surface area is 0.64 cm 2 ) a monolayer is equivalent to ≈2.62 × 10 14 total number of adsorbed MeCl molecules. The first two equations below define the electron flux, the dissociation, and recombination of CD 3 Cl and its products (methyl radical and chlorine anion) as a function of incident electrons:…”

“…The denominator value was set at 5.25 × 10 14 molecules, the estimated value equivalent to 2 ML of MeCl 57. Open red circles are assigned to 10 ML thick ASW films and full black circles to40 ML samples.…”

The promotion of CO dissociation by molybdenum oxide overlayers on rhodium

“…The sample bias was −19 V and the relative WF values were derived by an accuracy of around 0.1 eV comparing the positions of the inflexion points in the current vs. voltage curves [22] with that for the nearly stoichiometric TiO 2 (110) surface. Second, sensitive non-contact WF measurements were performed in a temperature-programmed manner [23] by a Besocke type Kelvin-probe with a sensitivity of 1 meV.…”

“…4, the amount of molecular state seems less than that of recombinative one. This can be associated with the dipole moment of adsorbed states [23]. Accordingly, the dissociation products, O and C adatoms seems to have a larger average dipole moment than the CO molecule.…”