Quantum tunneling of oxygen atoms on very cold surfaces

Journal article (2013)

Authors

Marco Minissale Observatoire de Paris
Emanuele Congiu Observatoire de Paris
Saoud Baouche Observatoire de Paris
Henda Chaabouni Observatoire de Paris
Audrey Moudens Observatoire de Paris
Francois Dulieu Observatoire de Paris
M. Accolla Centro Direzionale Isola C4
S.M. Cazaux Rijksuniversiteit Groningen
Giulio Manicò University of Catania
Valerio Pirronello University of Catania
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Published Date

2013

Language

English

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Abstract

Any evolving system can change state via thermal mechanisms (hopping a barrier) or via quantum tunneling. Most of the time, efficient classical mechanisms dominate at high temperatures. This is why an increase of the temperature can initiate the chemistry. We present here an experimental investigation of O-atom diffusion and reactivity on water ice. We explore the 6-25 K temperature range at submonolayer surface coverages. We derive the diffusion temperature law and observe the transition from quantum to classical diffusion. Despite the high mass of O, quantum tunneling is efficient even at 6 K. As a consequence, the solid-state astrochemistry of cold regions should be reconsidered and should include the possibility of forming larger organic molecules than previously expected.