Hydrogen peroxide and ammonia on protonated ice clusters

Area of Science:

• Physical Chemistry
• Atmospheric Chemistry
• Materials Science

Background:

• Protonated water clusters are crucial in atmospheric and astrophysical environments.
• Understanding the structural stability of ice clusters with impurities is key to various chemical processes.
• Previous studies identified specific stability peaks in pure protonated ice clusters.

Purpose of the Study:

• To investigate the stability patterns of protonated ice clusters containing ammonia and hydrogen peroxide.
• To determine the structural integration of ammonia and hydrogen peroxide within ice clusters.
• To elucidate the influence of temperature on the stability of these mixed clusters.

Main Methods:

• Utilized a temperature-controlled source for protonated water clusters.
• Employed high-resolution mass spectrometry to analyze cluster stability.
• Performed density functional theory calculations for structural analysis.

Main Results:

• Pure protonated ice clusters exhibit distinct stability peaks at 21 and 28 molecules, with structures up to n=55.
• Ammonia and hydrogen peroxide incorporation shifts these stability peaks but does not disrupt the underlying ice structure.
• Density functional theory calculations indicate additives reside on the surface of a 21-molecule dodecahedral cluster, not within its core.

Conclusions:

• The crystalline structure of protonated ice is robust and accommodates impurities like ammonia and hydrogen peroxide.
• Additives are integrated into the existing ice framework, primarily at surface sites.
• Temperature plays a role in the stability and structural arrangement of these mixed ice clusters.