Identifying Electronic Doorway States in the Secondary Electron Emission from Layered Materials

TL;DR

This study uncovers Feshbach resonances in secondary electron emission from layered materials like graphene, revealing layer-dependent doorway states that influence electron emission processes.

Contribution

It identifies and characterizes interlayer Feshbach resonances as doorway states in secondary electron emission, supported by experimental and theoretical analysis.

Findings

Resonance features are linked to interlayer Feshbach states.

Doorway states emerge only in samples with more than five layers.

Layer-dependent electron emission mechanisms are elucidated.

Abstract

We investigate the secondary low-energy electron emission induced by inelastic electron scattering from graphene and layered materials thereof. By applying a coincidence detection of the primary scattered and the emitted secondary electron we unravel pronounced resonance features otherwise overshadowed by the largely structureless secondary electron energy distribution. Supported by density functional theory calculations we show that these structures are the signature of prominent Feshbach resonances above the vacuum threshold which originate from interlayer states acting as a doorway state for electron emission. Remarkably, some of these doorway states open up only for samples with more than five layers.