Glycine-ice nanolayers: morphology and surface energetics

Area of Science:

• Surface science
• Materials science
• Physical chemistry

Background:

• Ultrathin films are crucial in various scientific fields.
• Understanding the behavior of water and organic molecules on surfaces is important for astrobiology and materials science.

Purpose of the Study:

• To investigate the structural and thermal properties of ultrathin glycine-ice nanolayers.
• To explore the influence of glycine on the phase transitions and desorption behavior of water ice.

Main Methods:

• Preparation of ultrathin glycine-ice films in ultrahigh vacuum.
• Analysis using temperature-programmed desorption (TPD).
• X-ray photoelectron spectroscopy (XPS) and work function measurements.

Main Results:

• Glycine at low coverage suppresses the amorphous-to-crystalline ice phase transition, lowering water desorption temperature.
• Thicker glycine overlayers kinetically hinder water desorption until glycine mobility increases.
• Ice overlayers do not wet glycine films; glycine exhibits hydrophobic behavior in mixed layers, leading to phase separation.

Conclusions:

• Glycine's presence significantly alters the structure and thermal properties of water ice nanolayers.
• The arrangement of glycine and water influences desorption kinetics and film morphology.
• These findings have implications for understanding icy bodies in space and designing novel materials.