Site-selective-induced isomerization of formamide

Area of Science:

• Physical Chemistry
• Ultrafast Spectroscopy
• Photochemistry

Background:

• X-ray free-electron lasers (XFELs) offer unprecedented capabilities for probing matter with high temporal resolution.
• Multi-color femtosecond X-ray pulses enable site-selective excitation and observation of molecular dynamics.
• Understanding ultrafast phenomena is crucial for controlling chemical reactions.

Purpose of the Study:

• To investigate the isomerization of formamide using a site-selective two-color X-ray femtosecond pump-probe technique.
• To demonstrate the control over chemical bond breaking through core excitation.
• To observe real-time hydrogen migration during X-ray-induced reactions.

Main Methods:

• Utilizing a two-color X-ray femtosecond pump-probe sequence at an XFEL facility.
• Employing site-selectivity to excite specific atomic sites within the formamide molecule.
• Monitoring changes in the chemical environment using X-ray probe pulses and measuring chemical shifts.

Main Results:

• The molecular response to X-ray excitation is highly dependent on the targeted atomic site.
• Core excitation, specifically the N1s → π* transition, effectively induces formamide isomerization.
• Real-time observation of hydrogen migration was achieved by tracking chemical shifts.

Conclusions:

• Site-selective core excitation provides precise control over X-ray-induced photochemistry.
• The N1s → π* transition is a viable pathway for initiating isomerization and hydrogen migration in formamide.
• This study highlights the potential of XFELs for advancing X-ray-induced photochemistry research.