REACTIONS OF N2O5 WITH PROTONATED WATER CLUSTERS H-30((H2O)(N), N=3)

Reactions of N2O5 with protonated and deuterated water clusters X(+)(X (2)O)(n=3-30) X = H or D, were studied at temperatures ranging from 12 8 to 300 K and at pressures between 0.23 and 0.66 Torr using a fast-fl ow apparatus. For cluster ions with n greater than or equal to 5, the reaction X(+)(X(2)O)n + N2O5 --> X(+)(X(2)O)(n-1)XNO(3) + XNO(3) was o bserved to occur at temperatures below 150 K. At somewhat larger value s of n which were acquired at temperatures about 130 K, the product io ns X(+)(X(2)O)(n-2)(XNO(3))(2) and X(+)(X(2)O)(n-3)(XNO(3))(3) were al so observed. The rate constants of the thermal energy reactions of N2O 5 With X(+)(X(2)O)(n=5-21) were found to display both a size and press ure dependence. The present work gives the first experimental evidence for the reaction between large protonated water clusters (n greater t han or equal to 5) and N2O5 under laboratory conditions, and the resul ts provide further information for unraveling the chemistry of the upp er atmosphere.