Simulated sample heating from a nanofocused X-ray beam.

Area of Science:

• Materials Science
• Physics
• Nanotechnology

Background:

• Advancements in synchrotron sources and X-ray optics increase flux density in nanofocusing experiments.
• High flux density raises concerns about X-ray induced radiation damage, particularly sample heating.

Purpose of the Study:

• To investigate X-ray induced sample heating in nanostructures using advanced simulations.
• To understand heat transport mechanisms and identify strategies for mitigating temperature increases.

Main Methods:

• Utilized time-resolved and steady-state three-dimensional finite-element modeling.
• Simulated heat generation and transport in representative nanostructures, specifically a semiconductor nanowire.

Main Results:

• X-ray absorption generates heat efficiently transported within nanowires, reaching homogeneity in approximately 5 ns.
• Conduction to the substrate is the primary heat loss mechanism, limited by heat transfer coefficient and interfacial area.
• Convective heat transfer to air is significant, while thermal radiation is negligible.
• Steady-state temperature increase is 8 K above room temperature under reference conditions.
• Without substrate heat transfer, temperatures rise to 55 K in air and exceed melting points in vacuum.
• Reducing X-ray focus size marginally increases maximum temperature at constant flux.

Conclusions:

• Effective heat dissipation to the surrounding environment, especially the substrate, is critical for managing X-ray induced heating.
• Strategies should focus on enhancing thermal contact and heat transfer pathways away from nanostructures.