  Understanding the factors influencing the lifetime of electronic states in
artificial quantum structures is of great significance for advancing quantum
technologies. This study focuses on CO-based quantum corrals on Cu(111).
Tunneling spectroscopy measurements reveal a strong correlation between the
size of the quantum corral and spectral width, characterized by a predominant
Gaussian line shape. We attribute this dominant Gaussian-shaped lifetime
broadening to the interaction of surface state electrons with the corral
boundary. To further investigate this phenomenon, we constructed corrals of
varying wall densities. Our findings indicate that elastic processes, such as
tunneling, are more sensitive to wall density than coupling to the bulk.
