Evidence for Eley-Rideal abstraction mechanism in reactive ion scattering of Cs+ from Pt(111) adsorbed with CO and CO2

Reactive Ion Scattering of Low Energy Cs+from Surfaces. A Technique for Surface Molecular Analysis

“…2 Since then, the RIS process has been examined on various surfaces and molecular adsorbate systems, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and the RIS mechanism has been investigated theoretically by using molecular dynamics simulations. [48][49][50][51][52][53] These studies indicate that the nature of the RIS process is quite universal and, therefore, it can be applied to the analysis of molecules on surfaces.…”

“…[4][5][6][48][49][50][51] In the early RIS experiments with chemisorbed species, where very small RIS yields (~10 -4 ) were observed, the RIS processes were considered to occur via a two-step mechanism; the Cs + impact causes collision-induced desorption (CID) of adsorbates and the Cs + -molecule association occurs in the outgoing trajectory. [4][5][6] However, in the later experiments, much higher (up to ~1) RIS yields were observed for small molecules physisorbed on surfaces, such as CO 2 , H2O, and noble gases on metal surfaces [51][52][53] and frozen water films. 8,[12][13][14][15]32 The early two-step mechanism cannot explain the high RIS yields observed in these experiments.…”

“…This procedure has been described for noble gases, CO, CO 2 , and H 2 O adsorbed on metal surfaces. 51,53 σ RIS represents the effective area (Å 2 ) on the surface within which the RIS product can be formed upon the collision of a Cs + projectile. Equation (3) (Fig.…”

Reaction of Nitrogen Dioxide with Ice Surface at Low Temperature (≤170 K)

“…The RIS yield, Y(x), is proportional to the surface population of species x and the specific detection efficiency of species x by RIS. 24 The RIS yields [Y(x)] of NO 2 , DNO 2 , and N 2 O 4 were calculated from the RIS intensities (shown in Figure 3a) and are plotted as a function of temperature in Figure 3b. Y(NO 2 ) decreased sharply in the range of 120−130 K and became undetectable above ∼132 K. Y(DNO 2 ) increased monotonically up to ∼130 K and then gradually decreased at higher temperatures.…”

“…This change is due to the roughening transition of the thinning ice film as a result of evaporation of water, which exposes patches of monolayer water on the Pt(111) surface. , It is necessary to discriminate the variations in the RIS intensity due to the surface condition changes from those due to changes in the surface species. For this, the absolute RIS intensity was converted to the RIS yield . The RIS yield represents the normalized RIS intensity and is defined as Y ( x ) = I x / ∑I i , where I x is the RIS intensity of species x and ∑ I i is the summation over all RIS signals, including Cs + .…”