Ultrafast hot-electron dynamics observed in Pt( -)(3) using time-resolved photoelectron spectroscopy

Area of Science:

• Physical Chemistry
• Atomic and Molecular Physics
• Femtochemistry

Background:

• Understanding electron dynamics in small metal clusters is crucial for catalysis and materials science.
• Anions offer unique electronic properties compared to neutral species.
• Previous studies on metal cluster relaxation times provide a baseline for comparison.

Purpose of the Study:

• To investigate the excited-state lifetime of the triply negative platinum cluster ion, Pt( -)(3).
• To explore the mechanisms governing ultrafast electron relaxation in atomic clusters.
• To compare the relaxation dynamics of Pt( -)(3) with bulk metallic systems.

Main Methods:

• Time-resolved two-photon photoelectron spectroscopy was employed.
• Femtosecond laser pulses at 1.5 eV photon energy were used in a pump-probe setup.
• Analysis of time-dependent photoelectron distributions provided decay information.

Main Results:

• The lifetime of optically excited states in Pt( -)(3) was determined to be less than 70 femtoseconds.
• This rapid decay indicates exceptionally fast electron relaxation.
• The observed lifetime is comparable to relaxation times in bulk metals.

Conclusions:

• The ultrafast electron relaxation in Pt( -)(3) is unexpectedly rapid for a triatomic cluster.
• Inelastic electron-electron scattering is proposed as the dominant relaxation mechanism.
• These findings suggest that small metal clusters can exhibit metallic-like electron dynamics.