Hydrogen atom quantum diffusion in solid parahydrogen: The H + N2O → cis-HNNO → trans-HNNO reaction
Fredrick M Mutunga1, Kelly M Olenyik2, Aaron I Strom2
1Department of Chemistry, Pwani University, Kilifi, 80108, Kenya.
The Journal of Chemical Physics
|January 8, 2021
Summary
Quantum diffusion of hydrogen atoms in solid parahydrogen was observed using infrared spectroscopy. This quantum effect influences reaction rates, unlike classical kinetics, and is temperature-dependent below 2.8 K.
Area of Science:
- Physical Chemistry
- Quantum Mechanics
- Spectroscopy
Background:
- Investigating the behavior of hydrogen atoms in solid parahydrogen is crucial for understanding quantum phenomena in condensed matter.
- Previous studies have explored diffusion in solid hydrogen, but direct observation of quantum diffusion influencing reactivity is limited.
Purpose of the Study:
- To investigate the diffusion and reactivity of hydrogen atoms in solid parahydrogen at low temperatures (1.5–4.3 K).
- To elucidate the role of quantum diffusion in the reaction kinetics of hydrogen atoms with nitrous oxide (N₂O).
Main Methods:
- High-resolution infrared spectroscopy was employed to monitor reactions in solid parahydrogen.
- In situ photolysis of N₂O at 193 nm was used to generate hydrogen atoms.
- Reaction kinetics were analyzed by varying N₂O concentration and temperature.
Main Results:
- Hydrogen atoms were observed to move via quantum diffusion through solid parahydrogen.
- The reaction rate of hydrogen atoms with N₂O showed an inverse dependence on N₂O concentration, confirming quantum diffusion.
- The reaction was found to be highly selective at temperatures below 2.8 K.
Conclusions:
- Quantum diffusion significantly influences the reactivity of hydrogen atoms in solid parahydrogen.
- The observed phenomena lack analogies in classical reaction kinetics.
- Low-temperature selectivity plays a key role in the observed reaction dynamics.
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