Structure and fragmentation of doubly ionized HNCS

Area of Science:

• Chemical Physics
• Atomic and Molecular Physics
• Quantum Chemistry

Background:

• Isothiocyanic acid (HNCS) is a molecule with interesting electronic properties.
• Understanding its ionization behavior is crucial for various chemical and physical applications.

Purpose of the Study:

• To measure the double ionization spectra of HNCS.
• To determine the adiabatic double ionization energy of HNCS.
• To investigate the dissociation channels of doubly ionized HNCS.

Main Methods:

• Multi-electron and multi-ion coincidence techniques were employed.
• High-level theoretical calculations, including electronic structure calculations, were performed.
• Systematic elongation of molecular bonds (H-NCS, HN-CS, HNC-S) was used to analyze dissociation.

Main Results:

• The adiabatic double ionization energy of HNCS was determined to be 27.1 ± 0.1 eV, forming the X 3A″ ground state of HNCS2+.
• The adiabatic double ionization energy of the NCS fragment was found to be 30.95 ± 0.5 eV.
• Dissociation channels leading to C+ and NS+ were observed, suggesting potential structural rearrangements.

Conclusions:

• The study provides key energetic and mechanistic insights into the double ionization of HNCS.
• The observed dissociation channels highlight the complexity of molecular fragmentation following double ionization.
• This research contributes to a deeper understanding of molecular dynamics under high-energy conditions.