Characterisation of the Formation Process of Carbon Nanomembranes (CNMs) with Single and Double Electron Spectroscopy

Abstract

Mechanically stable Carbon nanomembranes (CNMs) can be formed through electron- induced crosslinking of self-assembled monolay- ers (SAMs) (see Figure 1a). Owing to their molecular thickness (⇠ 1 nm) and tunable chem- ical properties, CNMs are promising candidates for technical applications such as water purifica- tion and biosensing [3]. Not only the microscopic pathway governing the transition from a SAM to a CNM remains insu ciently understood [1] but also the atomic structure of the resulting mem- branes is illusive due to inaccessibility to con- ventional characterization techniques including TEM, AFM, and XRD [2]. In the present study, crosslinking is induced in-situ using low-energy electrons with a primary energy of 100eV. The evolution of the system is monitored by reflective electron energy loss spectroscopy (REELS) at several probing ener- gies. Complementary electron pair spectroscopy measurements are carried out by detecting scat- tered primary electrons in coincidence with emit- ted secondary electrons, both before and after crosslinking (see Figure 1b). The REEL spectra reveal continuous inten- sity changes of characteristic energy-loss features during irradiation. Coincidence measurements further enable these loss processes to be asso- ciated with distinct energy-dissipation channels involving emission of secondary electrons or the absence thereof. Our observations are discussed in relation to atomic structural models proposed for these membranes [2].