Resonance electron capture by serine.

Area of Science:

• Physical Chemistry
• Chemical Physics
• Molecular Physics

Background:

• Amino acids are fundamental biological molecules.
• Understanding electron interactions with biomolecules is crucial for radiobiology and astrobiology.
• Dissociative electron attachment (DEA) is a key process for negative ion formation in molecules.

Purpose of the Study:

• Investigate the formation pathways of negative ions from the amino acid serine.
• Characterize the energy-dependent cross sections of DEA to serine.
• Elucidate the role of specific molecular groups, like the second OH, in DEA fragmentation.

Main Methods:

• Utilized two crossed electron/molecular beam techniques.
• Measured resonance electron capture mass spectra and effective ion yield curves.
• Performed quantum chemical calculations to interpret reaction mechanisms.

Main Results:

• Detected 16 distinct negative ions formed via DEA to serine.
• Identified dominant negative ion formation at electron energies near 0, 1.3, 5, and 8 eV.
• The (M-H)(-) ion was the primary product, with a cross section over 20 times larger than other fragments.
• Observed influence of the second OH group on specific dissociative channels.

Conclusions:

• The study provides detailed insights into DEA to serine.
• The (M-H)(-) channel is highly favored at low electron energies.
• Quantum chemical calculations aid in understanding the fragmentation dynamics of serine under electron impact.