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Table 1.

Model parameters.

Parameter Symbol Value
Sticking coefficient Ps 0.5
Reactive desorption efficiency aRRK 0.01
Ratio of surface diffusion barriers to desorption energies Eb1Ed 0.5
Ratio of bulk diffusion barriers to desorption energies Eb2Ed 0.7
Barrier thickness b 1 Å
Grain radius r 0.1 μm
Dust grain density ρd 3 g cm−3
Dust-to-gas mass ratio md∕g 0.01
Number of absorption sites on each grain S 1.0 × 106
Surface density of sites NS 7.96 × 1014 sites cm−2
Unattenuated FUV flux χ χ0 = 1
Cosmic ray ionization rate ζCR 1.3 × 10−17 s−1
Fraction of the timescale between two cosmic-ray heating events f 3.16 × 10−19
Characteristic vibrational frequency ν0 1 × 1012 s−1

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