<title>Abstract</title>
When the hydrogen isotope atom is injected into the amorphous carbon with the incident energies <italic>E</italic>
_in of 20, 50, and 80 eV, we obtain the following physical quantities of hydrogen isotope atoms/molecules emitted from the amorphous carbon using molecular dynamics and heat conduction hybrid simulation. The physical quantities are the time evolution of the emission rate, the depth distribution of the original location of the hydrogen emitted from the target, the polar angular dependence, and the translational, rotational, and vibrational energy distributions. In addition, the approximate analysis yields the emission distributions at the vibrational (<italic>v</italic>) and rotational (<italic>J</italic>) levels. Using these distributions, we evaluate the rotational temperature <italic>T</italic>
_rot for <italic>v</italic> = 0 and small <italic>J</italic> states. From the above, it is found that molecules with higher rotational levels <italic>J</italic> tend to be emitted as <italic>E</italic>
_in increases or as the mass of hydrogen isotope increases. Moreover, the isotope effect appears in the mass dependence of <italic>T</italic>
_rot.