Spatially dependent dose rate in liquid cell transmission electron microscopy.

Area of Science:

• Materials Science
• Chemistry
• Physics

Background:

• Liquid cell electron microscopy (LCEM) is crucial for studying nanomaterials in situ.
• Beam-induced radiolysis in LCEM can alter chemical environments, affecting observed reactions.
• Uniform beam effects are typically assumed, but interface effects are overlooked.

Purpose of the Study:

• To investigate the spatial variation of electron beam energy deposition in liquid cells.
• To understand how interfaces influence beam-induced radiolysis.
• To quantify the impact of different interface materials on radiolysis.

Main Methods:

• Simulations and experimental measurements of electron energy deposition in water-filled liquid cells.
• Analysis of secondary and backscattered electron contributions from cell walls.
• Quantification of local dose rates and radiolysis species concentrations near interfaces.

Main Results:

• Electron beam energy deposition is non-uniform in liquid cells, especially near interfaces.
• Cell walls act as sources of secondary and backscattered electrons, increasing local dose rates.
• Dose rates can increase severalfold within tens of nanometers of a water/Au interface, affecting hydrated electron concentrations.

Conclusions:

• Interface effects significantly alter beam-induced radiolysis in liquid cells.
• The assumption of uniform beam effects is invalid near solid-liquid interfaces.
• Understanding these spatial variations is critical for accurate LCEM studies of interfacial nanomaterial processes.