Evidence for hydrogen desorption through both interdimer and intradimer paths from Si(100)-(2 x 1)

Area of Science:

• Surface Science
• Physical Chemistry
• Materials Science

Background:

• Controversial issues persist regarding hydrogen desorption and adsorption mechanisms on Si(100)-(2 x 1) surfaces.
• The relative importance of interdimer and intradimer desorption pathways remains unclear, with conflicting evidence from different experimental techniques.

Purpose of the Study:

• To further investigate and clarify the dominant desorption pathways for hydrogen on Si(100)-(2 x 1).
• To provide evidence supporting the inclusion of intradimer desorption paths in understanding hydrogen desorption dynamics.

Main Methods:

• Density-functional calculations of hydrogen translational excitation.
• Mean-field analysis of thermal-desorption experiments across various ramp rates.
• Monte Carlo simulations of nanosecond-pulse-laser desorption experiments.

Main Results:

• The intradimer and 3H interdimer desorption paths are identified as major contributors to the translationally hot fraction in the desorbate.
• The findings reconcile conflicting data from nanosecond-pulse-laser and thermal-desorption time-of-flight measurements.
• The 2H interdimer path is also shown to contribute to the translationally hot desorption fraction at lower coverages.

Conclusions:

• The study provides strong evidence for the significant role of intradimer desorption paths in hydrogen desorption from Si(100)-(2 x 1).
• A comprehensive understanding of hydrogen desorption dynamics requires considering both intradimer and specific interdimer pathways (3H and 2H).
• The combined theoretical and simulation approach offers a robust framework for resolving long-standing controversies in surface science.