Wavelength-dependent photofragmentation of pyrazine

Area of Science:

• Astrochemistry
• Physical Chemistry
• Photochemistry

Background:

• Interstellar molecules form via UV photon-induced dissociation.
• Photodissociation regions (PDRs) have high UV intensities crucial for chemical processes.
• Pyrazine is a nitrogen heterocycle relevant to astrobiology and astrochemistry.

Purpose of the Study:

• Investigate the gas-phase photo-fragmentation of pyrazine using UV radiation.
• Compare fragmentation patterns under different UV wavelengths (266 nm and 355 nm).
• Identify key molecular fragments and explore novel dissociation pathways.

Main Methods:

• Photo-fragmentation experiments using 266 nm and 355 nm UV lasers.
• Analysis of cationic fragmentation patterns at varying laser intensities.
• Identification of nitrogen-bearing fragment cations and hydrocarbons.

Main Results:

• Significant wavelength-dependent differences in pyrazine fragmentation were observed.
• Nitrogen-bearing cations and hydrocarbons were identified as major products.
• New fragmentation channels, including [FORMULA], [FORMULA], and [FORMULA], were observed under 355 nm irradiation.
• The formation of [FORMULA] suggests photoisomerization prior to dissociation.

Conclusions:

• UV-driven pyrazine fragmentation exhibits wavelength dependency.
• Photoisomerization plays a role in pyrazine dissociation pathways under specific UV conditions.
• Experimental data provide crucial constraints for astrochemical models of UV-driven molecular processes in PDRs and planetary atmospheres.