Assuming thermal equilibrium is fully achieved at certain stage between laser irradiation and ion extraction in the gas phase, the estimated ion yield at 1,000 K is 10 -16 (see supporting information for calculation), which is much lower than the experimentally determined ion yields of 10 -7 -10 -8 . At 2,200 K, the estimated ion yield is 10 -8 , which is consistent with the experimental number. However, the actual temperature may be lower, and if that is the case, a portion of the ions detected may be from the solid sample, in which the ion to neutral ratio is higher due to shielding by neutral molecules.