Thermal evaporation of pyrene clusters

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Chemistry

Background:

• Pyrene clusters are relevant in materials science and physical chemistry.
• Understanding their thermal stability is crucial for predicting their behavior in various applications.
• Previous studies have explored the properties of pyrene clusters, but detailed analysis of charged cluster evaporation and stability remains an active area of research.

Purpose of the Study:

• To investigate the thermal evaporation and stability of positively charged pyrene clusters (C16H10)n.
• To determine the dissociation energies of these clusters experimentally and theoretically.
• To explore the influence of charge on the stability of pyrene clusters.

Main Methods:

• Experimental measurement of thermal evaporation rates for mass-selected pyrene clusters (n=3-40) using a gas aggregation source, thermalization chamber, and time-of-flight mass spectrometer.
• Microcanonical Phase Space Theory (PST) simulations to determine dissociation energies by fitting experimental breakdown curves.
• Density Functional based Tight Binding combined with Configuration Interaction (CI-DFTB) calculations for smaller clusters (n=2-7) to determine harmonic frequencies and theoretical dissociation energies.

Main Results:

• Experimental breakdown curves of pyrene clusters were well-fitted using the PST model.
• Dissociation energies showed significant size-dependent variations.
• Smaller charged pyrene clusters exhibited considerably higher dissociation energies compared to neutral clusters, attributed to charge resonance.

Conclusions:

• The study successfully characterized the thermal evaporation and stability of charged pyrene clusters.
• Phase Space Theory provides a reliable model for analyzing cluster dissociation dynamics.
• Charge resonance significantly enhances the stability of smaller pyrene clusters, offering insights into their electronic properties.