We report a photoelectron spectroscopy and computational study of hydrated N3- anion clusters, 
N3-(H2O)n (n = 0-16), in the gas phase.  Photoelectron spectra of the solvated azide anions 
were observed to consist of a single peak, similar to that of the bare N3-, but the spectral 
width was observed to broaden as a function of cluster size due to solvent relaxation upon 
electron detachment.  The adiabatic and vertical electron detachment energies were measured 
as a function of solvent number.  The measured electron binding energies indicate that the 
first four solvent molecules have much stronger interactions with the solute anion, forming 
the first solvation shell.  The spectral width levels off at n = 7, suggesting that three 
waters in the second solvation shell are sufficient to capture the second shell effect in the 
solvent relaxation.  Density functional calculations were carried out for N3- solvated by one 
to five waters and showed that the first four waters interact directly with N3- and form the 
first solvation shell on one side of the solute.  The fifth water does not directly solvate 
N3- and begins the second solvation shell, consistent with the observed photoelectron data.  
Molecular dynamics simulations on both solvated clusters and bulk interface revealed that 
the asymmetric solvation state in small clusters persist for larger systems and that N3- 
prefers interfacial solvation on water clusters and at the extended vacuum/water interface.