A novel method for determining absolute coverages by temperature programmed desorption with application to the adsorption of CH3I on MgO(100)

Femtosecond time-resolved photodissociation dynamics of methyl halide molecules on ultrathin gold films

“…At submonolayer coverage just one desorption peak, which shifts to lower temperature with increasing coverage, appears in the TPD spectra. A similar desorption feature has been observed for CH 3 I [10,18] and CH 3 Br [12] on MgO, CH 3 Br on LiF [19], and CH 3 Cl on Pd(100) [20], as well as for CH 3 Cl, CH 3 Br and CH 3 I on GaAs(110) [21–22], and the coverage dependence is attributed to the adsorbate–adsorbate repulsion that results from the interaction between the static dipole moments of adsorbed molecules. Due to this lateral repulsion between the adsorbate molecules, the activation energy for desorption decreases with increasing coverage and, hence, the desorption temperature decreases.…”

Surface-aligned femtochemistry: Photoinduced reaction dynamics of CH3I and CH3Br on MgO(100)

“…2(a) displays a series of TPD spectra that were recorded at different methyl iodide dosages between 0.3 and 1 L (Langmuir; 1 L ¼ 1 Â 10 À6 torr s). As reported previously, 8,17 methyl iodide is adsorbed molecularly on the MgO(100) surface and desorbs without decomposition. The shift of the maximum of the desorption intensity in the TPD spectra to lower temperatures with increasing the methyl iodide coverage is attributed to a repulsive adsorbate-adsorbate interaction due to an adsorbate structure with the methyl iodide symmetry axis and hence the permanent dipole moment of the molecules aligned parallel to each other and parallel to or slightly tilted from the surface normal.…”

Surface‐Aligned Femtochemistry: Real‐Time Dynamics of Photoinduced I2 Formation from CD3I on MgO(100)

“…[13,14] On magnesia ultrathin films on Mo(100), a similar orientation was reported previously, with the methyl group heading toward the substrate surface (cf. Figure 1 a).…”