Role of Gas Molecule Complexity in Environmental Electron Microscopy and Photoelectron Yield Spectroscopy

Abstract

Environmental scanning electron microscopy (ESEM) and environmental photoelectron yield spectroscopy (EPYS) enable electron imaging and spectroscopy of surfaces and interfaces in low-vacuum gaseous environments. The techniques are both appealing and limited by the range of gases that can be used to amplify electrons emitted from a sample and used to form images/spectra. However, to date only HO and NH gases have been identified as highly favorable electron amplification media. Here we demonstrate that ethanol vapor (CHCHOH) is superior to both of these and attribute its performance to its molecular complexity and valence orbital structure. Our findings improve the present understanding of what constitutes a favorable electron amplification gas and will help expand the applicability and usefulness of the ESEM and EPYS techniques.

In Situ Kinetic Observations on Crystal Nucleation and Growth

“…Since the commercialization of the first SEM in 1965, many attempts were made to investigate the possibility of in situ observing samples in the SEM chamber under their “natural” liquid or heating environments. These include the observations of wet chemical reactions, sintering, melting, and recrystallization of metallic or ceramic materials, and the development of the environmental SEM (ESEM) thus began in the later 70s with the work of Danilatos and Robinson. ,− …”

Metrology of crystal defects through intensity variations in secondary electrons from the diffraction of primary electrons in a scanning electron microscope

“…Here, we broadly classify the incident electron beam in the gaseous environment in two parts: the unscattered beam (retaining the energy distribution and beam size of the incident beam), and the scattered beam where the beam trajectory is broadened [12]. The type of gas used plays a role in the amplification process, and numerous gases including air, H2O (water vapour), CO2, N2O, N2, He, NH3 and CH3CH2OH have been used to date [16]. Among these gases, water vapour is the most commonly used, and is the one used in our present work.…”