High resolution slice imaging of a molecular speed distribution

Area of Science:

• Chemical Physics
• Molecular Dynamics
• Spectroscopy

Background:

• Molecular fragment speed distributions are crucial for understanding chemical reactions and photodissociation.
• Previous methods lacked the resolution to precisely measure these distributions.
• High-resolution techniques are needed to probe complex molecular dynamics.

Purpose of the Study:

• To develop and demonstrate a high-resolution slice imaging technique for measuring molecular fragment speed distributions.
• To achieve speed resolution at the permille level.
• To validate the technique by measuring the CD(3) speed distribution from CD(3)I photolysis.

Main Methods:

• Implementation of a high-resolution single-particle slice imaging detector.
• Utilization of a two-colour resonance-enhanced multi-photon ionisation (REMPI) scheme to minimize electron kick broadening.
• Measurement of the three-dimensional speed distribution of CD(3) fragments.

Main Results:

• Achieved a speed resolution of FWHM(v)/v(mp) = 1.9 x 10(-3) (permille level).
• Demonstrated imaging of the three-dimensional speed distribution with a resolution of FWHM(v) = 6.7 m s(-1) for v(mp) = 3473 m s(-1).
• Successfully measured the CD(3) speed distribution from CD(3)I photolysis.

Conclusions:

• Slice imaging is a powerful technique for high-resolution measurement of molecular fragment speed distributions.
• The developed method significantly enhances the ability to study photodissociation dynamics.
• This technique has broad potential for investigating molecular clouds and reaction mechanisms.