Desorption of physisorbed molecules from the sapphire surface by yttrium-aluminum garnet laser second-harmonic radiation

Energy fluence dependences for the laser-enhanced desorption of physisorbed NO, SO2, CO2, NH3, and C6H6 molecules from the sapphire surface by second- harmonic radiation of a pulse neodymium-doped yttrium-aluminum garnet (YAG) laser were experimentally studied. It was shown that the one-photon absorp tion of radiation at the second-harmonic wavelength (lambda = 532 nm) by ad sorbed NO molecules was so low that their desorption was accomplished via t wo-photon absorption. Nonlinear energy fluence dependence with a nonlineari ty index of greater than 4 was observed for polyatomic molecules. The desor ption of these molecules did not occur at the YAG laser emission wavelength (lambda = 1064 nm), thus suggesting that the long-wavelength edge of their one-photon absorption lies within the range 1064-532 nm.