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Question
(a) An excimer laser used for vision correction emits 193-nm UV. Calculate the photon energy in eV. (b) These photons are used to evaporate corneal tissue, which is very similar to water in its properties. Calculate the amount of energy needed per molecule of water to make the phase change from liquid to gas. That is, divide the heat of vaporization in kJ/kg by the number of water molecules in a kilogram. (c) Convert this to eV and compare to the photon energy. Discuss the implications.
1. $6.42\textrm{ eV}$
2. $6.75\times 10^{-20}\textrm{ J/molecule}$
3. $0.421\textrm{ eV/molecule}$. Each photon can vaporize approximately 15 water molecules.
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